Kilogram to Pennyweight Converter
Convert kilograms to pennyweights with our free online weight converter.
Quick Answer
1 Kilogram = 643.014931 pennyweights
Formula: Kilogram × conversion factor = Pennyweight
Use the calculator below for instant, accurate conversions.
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All conversion formulas on UnitsConverter.io have been verified against NIST (National Institute of Standards and Technology) guidelines and international SI standards. Our calculations are accurate to 10 decimal places for standard conversions and use arbitrary precision arithmetic for astronomical units.
Kilogram to Pennyweight Calculator
How to Use the Kilogram to Pennyweight Calculator:
- Enter the value you want to convert in the 'From' field (Kilogram).
- The converted value in Pennyweight will appear automatically in the 'To' field.
- Use the dropdown menus to select different units within the Weight category.
- Click the swap button (⇌) to reverse the conversion direction.
How to Convert Kilogram to Pennyweight: Step-by-Step Guide
Converting Kilogram to Pennyweight involves multiplying the value by a specific conversion factor, as shown in the formula below.
Formula:
1 Kilogram = 643.015 pennyweightsExample Calculation:
Convert 5 kilograms: 5 × 643.015 = 3215.07 pennyweights
Disclaimer: For Reference Only
These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.
Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.
Need to convert to other weight units?
View all Weight conversions →What is a Kilogram and a Pennyweight?
The kilogram (symbol: kg) is the base unit of mass in the International System of Units (SI). It is one of the seven SI base units and forms the foundation for measuring mass and weight in the metric system.
Modern Definition (2019): The kilogram is defined by fixing the numerical value of the Planck constant (h) to be exactly 6.62607015×10⁻³⁴ joule-seconds (J⋅s). This definition, adopted on May 20, 2019 (World Metrology Day), replaced the previous definition based on a physical artifact.
Key relationships:
- 1 kilogram = 1,000 grams (g)
- 1 kilogram = 1,000,000 milligrams (mg)
- 1 kilogram = 0.001 metric tons (tonnes)
- 1,000 kilograms = 1 metric ton
In terms of imperial/US customary units:
- 1 kilogram ≈ 2.20462 pounds (lb) - Convert kg to lb
- 1 kilogram ≈ 35.274 ounces (oz) - Convert kg to oz
- 1 kilogram ≈ 0.157 stones (st) - Convert kg to stones
Visual perspective (how heavy is it?):
- 1 kg ≈ Liter bottle of water
- 1 kg ≈ Small laptop or tablet
- 1 kg ≈ Bag of sugar
- 1 kg ≈ Two pineapples
- 5 kg ≈ Newborn baby
- 10 kg ≈ Small dog or cat
Important distinction: While "mass" and "weight" are scientifically different (mass is the amount of matter, weight is gravitational force), in everyday usage, kilograms measure what we commonly call "weight."
Convert between weight units: kilogram converter
What Is a Pennyweight?
The pennyweight (symbol: dwt) is a unit of mass within the troy weight system, equal to exactly 1.55517384 grams or 1/20th of a troy ounce. It consists of precisely 24 grains, making it a convenient intermediate unit for measuring precious metals and gemstones.
Troy vs. Avoirdupois Systems
The pennyweight belongs to the troy weight system, which differs fundamentally from the avoirdupois system used for most everyday weights:
- Troy system: 12 ounces = 1 pound (used for precious metals, gemstones)
- Avoirdupois system: 16 ounces = 1 pound (used for general commerce)
- Key difference: A troy ounce (31.1035 g) is heavier than an avoirdupois ounce (28.3495 g), but a troy pound (373.24 g) is lighter than an avoirdupois pound (453.59 g)
Official Definition
Since the 1959 international yard and pound agreement, the pennyweight is defined as:
1 dwt = 24 grains = 0.05 troy ounces = 1.55517384 grams (exact)
This definition is recognized by the United States, United Kingdom, Canada, Australia, New Zealand, and South Africa, ensuring consistency in precious metals trading worldwide.
Note: The Kilogram is part of the metric (SI) system, primarily used globally in science and trade. The Pennyweight belongs to the imperial/US customary system.
History of the Kilogram and Pennyweight
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French Revolution Origins (1795): During the development of the metric system, French scientists defined the "grave" (later renamed kilogram) as the mass of one cubic decimeter (liter) of pure water at 4°C (its maximum density). This provided a definition based on nature rather than arbitrary standards.
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Kilogram des Archives (1799): The first physical standard was created - a platinum cylinder kept in the French National Archives in Paris. This "Kilogram of the Archives" served as France's official kilogram standard.
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Treaty of the Metre (1875): Seventeen nations signed this international treaty, establishing global cooperation on measurement standards. This set the stage for creating an international kilogram prototype.
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International Prototype Kilogram - Le Grand K (1889): A precisely machined platinum-iridium (90% platinum, 10% iridium) cylinder was created and designated as the international standard. This cylinder, known as "Le Grand K" or the IPK, was:
- 39 millimeters in both height and diameter
- Stored under three nested bell jars at the BIPM in Sèvres, France
- The only SI unit still defined by a physical artifact (until 2019)
- Accessed only rarely for calibration purposes
-
The Problem with Le Grand K: Over time, scientists discovered that the IPK's mass was changing relative to its copies - by approximately 50 micrograms over a century. This was problematic because:
- The kilogram was drifting from its official definition
- No way to verify if the prototype was gaining or losing mass
- Physical objects can be damaged, contaminated, or lost
- Limited access meant difficult calibrations worldwide
-
Search for a New Definition (1990s-2010s): Scientists developed two approaches:
- Kibble Balance (formerly watt balance): Relates mass to electromagnetic force and the Planck constant
- Avogadro Project: Count atoms in a silicon sphere to define the kilogram
-
2019 Redefinition: On May 20, 2019 (World Metrology Day), the kilogram definition changed:
- Old: Mass of the International Prototype Kilogram
- New: Defined by fixing the Planck constant at exactly 6.62607015×10⁻³⁴ J⋅s
- This allows any properly equipped laboratory to reproduce the kilogram
- No longer depends on a physical object that could change or be damaged
-
Why the Planck Constant?: This quantum mechanical constant relates energy to frequency and appears in fundamental physics equations. By fixing its value, mass can be measured using electromagnetic force through a Kibble balance.
-
Global Impact: The kilogram is used by virtually every country worldwide. Even the United States, which uses pounds in daily life, uses kilograms extensively in:
- Scientific research
- International trade
- Medical dosing
- Manufacturing
- Athletics and sports
-
Historical Significance: The 2019 redefinition was the culmination of over a century of metrological advancement, representing humanity's shift from physical artifacts to universal physical constants.
Ancient Origins: The Silver Penny
The pennyweight's history traces to Anglo-Saxon England, where silver pennies served as both currency and weight standards. During the reign of King Offa of Mercia (757-796 AD), silver pennies were standardized at one pennyweight each, creating a direct relationship between monetary value and precious metal weight.
This system meant that:
- 1 silver penny = 1 pennyweight of silver
- 20 pennies = 1 shilling = 1 troy ounce of silver
- 240 pennies = 1 pound sterling = 1 troy pound of silver
This elegant correspondence between money and weight lasted nearly 1,200 years in principle, though the silver content of coins gradually decreased over centuries.
Medieval Standardization (1266-1327)
The Composition of Yards and Perches statute of 1266 under King Henry III formally standardized English weights and measures, including the pennyweight at 24 grains. This was reinforced by the Tractatus de Ponderibus et Mensuris (Treatise on Weights and Measures) issued during the reign of Edward I (1303-1307).
The Worshipful Company of Goldsmiths, granted its royal charter in 1327, became the official regulatory body for precious metals in England. The company enforced pennyweight standards through its hallmarking system, which required all gold and silver items to be assayed (tested for purity) and stamped with official marks. Goldsmiths' Hall in London became the center of this regulatory system—hence the term "hallmark."
Troyes Connection
The term "troy weight" derives from Troyes, France, a major medieval trading city hosting international fairs where merchants from across Europe gathered. By the 12th-13th centuries, Troyes had developed standardized weight systems for precious metals that were adopted by merchants throughout Europe.
English goldsmiths adopted the Troyes system because it was already used by continental traders, ensuring consistency in international precious metals commerce. The system's subdivision structure (1 pound = 12 ounces, 1 ounce = 20 pennyweights, 1 pennyweight = 24 grains) reflected medieval base-12 and base-20 counting preferences.
British Imperial Codification (1824-1878)
The British Weights and Measures Act of 1824 consolidated various troy weight standards used across Britain, officially defining the troy pound as 5,760 grains and the pennyweight as 1/240th of a troy pound (24 grains).
The Weights and Measures Act of 1878 refined these definitions and legally mandated troy weights for precious metals transactions throughout the British Empire. This act specified that gold, silver, platinum, and precious stones must be weighed using troy units, with the pennyweight serving as the practical working unit for jewelers and dealers.
American Adoption
The United States adopted the British troy system for precious metals following independence. The U.S. Coinage Act of 1792 established the dollar based on a specific weight of silver (371.25 grains = 15.4375 pennyweights), directly linking American currency to pennyweight standards.
The National Bureau of Standards (now NIST) formalized the pennyweight in U.S. regulations, and it remains a legally recognized unit for precious metals commerce under U.S. law today.
International Agreement (1959)
The 1959 international yard and pound agreement among English-speaking nations established exact metric equivalents for imperial units, defining the grain (and therefore the pennyweight) in terms of the kilogram:
- 1 grain = exactly 64.79891 milligrams
- 1 pennyweight = 24 grains = exactly 1.55517384 grams
This agreement ended minor variations in troy weight definitions across different countries and established the standard used worldwide today.
Modern Persistence
Despite metrication efforts in the United Kingdom (1965-present), Australia (1970s), and other Commonwealth nations, the pennyweight persists in the precious metals and jewelry industries. The unit's survival reflects:
- International trade standards: Precious metals are traded globally in troy ounces and pennyweights
- Industry infrastructure: Scales, reference books, and pricing systems are built around troy units
- Practical convenience: Pennyweights provide appropriate precision for jewelry work
- Legal requirements: Many jurisdictions still mandate troy weights for bullion hallmarking
The London Bullion Market Association (LBMA), established 1987, continues to use troy ounces (and by extension, pennyweights) as the global standard for precious metals trading, ensuring the unit's continued relevance.
Common Uses and Applications: kilograms vs pennyweights
Explore the typical applications for both Kilogram (metric) and Pennyweight (imperial/US) to understand their common contexts.
Common Uses for kilograms
The kilogram is the universal standard for mass measurement across virtually all applications worldwide:
Science and Research
The fundamental unit for mass in all scientific disciplines. Essential for chemistry, physics, biology, medicine, and engineering research conducted globally.
Scientific Applications:
- Chemistry: Measuring reactants, products, and samples
- Physics: Mass calculations in mechanics and dynamics
- Biology: Specimen weights, culture media
- Medicine: Drug dosing, patient measurements
- Materials science: Sample preparation and analysis
- Environmental science: Pollution measurements, soil samples
Why kilograms in science:
- SI base unit (international standard)
- Decimal-based for easy calculations
- Defined by fundamental constant (Planck constant)
- Required for publication in scientific journals
- Universal reproducibility in any laboratory
Convert for scientific work: kilograms to other units
Healthcare and Medicine
Standard for patient weight, drug dosing, and medical calculations in hospitals and clinics worldwide. Critical for accurate treatment.
Medical uses:
- Patient weight: Baseline health measurement
- Drug dosing: Many medications dosed per kg body weight
- Pediatric care: Growth charts in kg and cm
- BMI calculation: Weight (kg) ÷ height² (m)
- Fluid management: IV fluids calculated by body weight
- Nutritional assessment: Protein needs, calorie requirements
- Medical research: Study participant measurements
Dosing examples:
- Pediatric antibiotics: 10-15 mg per kg body weight
- Anesthesia: Calculated per kg
- Chemotherapy: Often dosed per kg or body surface area
- Emergency medications: Weight-based dosing critical
Why critical in medicine:
- Precision prevents overdosing or underdosing
- International medical protocols use kg
- Pediatric safety depends on accurate weights
- Research requires standardized measurements
Food Industry and Nutrition
Standard unit for food packaging, recipes, nutritional labels, and commercial food sales in metric countries and international trade.
Food industry uses:
- Packaging labels: "Net weight: 1 kg"
- Commercial sales: Produce sold per kg
- Nutritional information: Values per 100g or serving
- Recipe scaling: Professional cooking in kg
- Food safety: Portion control, serving sizes
- Import/export: International food trade
- Restaurant supplies: Ingredients ordered in kg
Retail examples:
- Fruits and vegetables: Priced per kg
- Meat and fish: Sold by kg or portion
- Bulk foods: Rice, flour, nuts sold in kg bags
- Deli counters: Sliced meats weighed in kg
Shipping and Logistics
International standard for package weight, freight calculations, and postal rates. Essential for global commerce and transportation.
Shipping applications:
- Package weight limits: Carriers specify max kg
- Freight charges: Calculated per kg or dimensional weight
- Postal rates: Tiered by kg (0-2 kg, 2-5 kg, etc.)
- Air cargo: Charged per kg
- Container shipping: Weight limits in kg
- Customs declarations: Product weights in kg
- Warehouse inventory: Stock measured in kg
Standard limits:
- Small parcel: Up to 2 kg
- Standard parcel: 2-20 kg
- Heavy parcel: 20-30 kg
- Freight: 30+ kg
Why kg in shipping:
- International standard (UPU uses kg)
- Simplifies cross-border shipping
- Aviation industry uses kg
- Maritime shipping uses metric tons (1,000 kg)
Athletics and Sports
Standard for athlete weight classes, equipment specifications, and performance measurements in international competition.
Weight classes (examples):
- Boxing: Flyweight (< 51 kg), Welterweight (< 69 kg), Heavyweight (> 91 kg)
- Wrestling: Multiple classes from 57 kg to 125 kg
- Weightlifting: Classes from 55 kg to 109+ kg
- MMA: Featherweight (66 kg), Middleweight (84 kg), etc.
- Rowing: Lightweight (< 72.5 kg men, < 59 kg women)
- Judo: Multiple classes from 60 kg to 100+ kg
Equipment standards:
- Shot put: 7.26 kg (men), 4 kg (women)
- Discus: 2 kg (men), 1 kg (women)
- Javelin: 800 g (men), 600 g (women)
- Hammer throw: 7.26 kg (men), 4 kg (women)
Performance metrics:
- Clean and jerk records (kg lifted)
- Total weight lifted in competitions
- Body composition tracking
Manufacturing and Industry
Critical for quality control, material specifications, and product development. Enables consistent production and international standards.
Manufacturing uses:
- Raw materials: Ordered and inventoried in kg
- Product specifications: Component weights in kg or grams
- Quality control: Weight tolerance checking
- Batch production: Recipe scaling by kg
- Packaging: Box and pallet weights
- Shipping calculations: Product + packaging weight
- Waste management: Scrap material measured in kg
Industries:
- Automotive: Vehicle weight specifications
- Aerospace: Critical weight calculations
- Pharmaceuticals: Active ingredient quantities
- Chemicals: Formulation by weight
- Textiles: Fabric weight per square meter (GSM)
Agriculture and Farming
Standard for crop yields, animal weights, feed quantities, and agricultural commodities worldwide.
Agricultural uses:
- Crop yields: Tons per hectare (1,000 kg = 1 ton)
- Livestock weights: Animal growth tracking
- Feed calculations: Feed ratios per kg body weight
- Fertilizer application: kg per hectare
- Produce sales: Market prices per kg
- Seed quantities: Planting rates in kg/hectare
- Harvest records: Total yield in kg or tons
Example yields:
- Wheat: 3,000-8,000 kg/hectare
- Corn: 5,000-12,000 kg/hectare
- Rice: 4,000-10,000 kg/hectare
Everyday Life (Metric Countries)
Daily measurements for body weight, shopping, cooking, and general household use in 95% of the world's countries.
Personal use:
- Body weight tracking (bathroom scale)
- Grocery shopping (price per kg)
- Cooking and baking (recipe measurements)
- Luggage weight (travel)
- Baby weight monitoring (growth charts)
- Fitness tracking (weight loss/gain goals)
- Pet weight (veterinary care)
Use our kilogram converter for everyday conversions.
When to Use pennyweights
1. Jewelry Manufacturing and Valuation
Jewelers use pennyweights as their primary working unit for several reasons:
Precision without unwieldiness: A pennyweight provides finer precision than troy ounces (1/20th oz increments) without requiring the tiny fractions that grain measurements would demand. A jeweler can easily work with "5.5 dwt of gold" rather than "110 grains" or "0.275 troy ounces."
Pricing calculations: Precious metal dealers quote prices per pennyweight for smaller quantities. For example, if gold is $2,000/troy ounce, it's $100/dwt ($2,000 ÷ 20). This makes quick calculations easier: a 6 dwt ring contains $600 worth of gold.
Material estimation: When designing custom jewelry, goldsmiths estimate required material in pennyweights: "This ring design will need approximately 8 pennyweights of 14-karat gold, plus 2 pennyweights for the setting."
Scrap valuation: When buying or selling scrap gold/silver, dealers weigh items in pennyweights to calculate melt value: "Your broken gold chain weighs 12.3 pennyweights at 14-karat purity, which contains 7.175 dwt of pure gold."
Industry standard scales: Professional jewelers' scales typically display troy ounces subdivided into 20 pennyweights, with precision to 0.01 dwt (0.24 grains).
2. Precious Metals Trading and Refining
Refinery lot tracking: When refineries process precious metals, they track batches in troy ounces and pennyweights: "Batch #4782: 347 oz 15 dwt of sterling silver scrap."
Assay reporting: Assay offices (testing precious metal purity) report results in pennyweights: "Sample contained 18.65 dwt of pure gold and 1.35 dwt of copper alloy."
Bullion fractional trading: Small precious metals dealers use pennyweights for transactions smaller than full troy ounces: "We buy silver at $1.20/dwt" ($24/oz).
Hallmarking records: Official hallmarking offices record item weights in pennyweights when stamping fineness marks: "Ring assayed and hallmarked: 5.2 dwt, 18kt gold."
3. Gemstone Settings and Diamond Work
While gemstones themselves are weighed in carats (1 carat = 200 mg), the metal settings are measured in pennyweights:
Prong settings: "Four-prong platinum setting for 1-carat diamond: 1.8 dwt" Bezels: "18kt gold bezel for round cabochon: 2.3 dwt" Channel settings: "Platinum channel for seven 0.25ct diamonds: 4.5 dwt"
Conversion reference: 1 pennyweight = 7.776 metric carats (though carats aren't used for metal)
4. Coin Collecting (Numismatics)
Coin collectors reference pennyweights to verify authenticity and silver/gold content:
Historical silver coins: Pre-1965 U.S. dimes, quarters, and half-dollars contain 90% silver. Their pennyweight ratings help collectors calculate precious metal value:
- 1964 Kennedy half-dollar: 7.234 dwt silver content
- 1964 Washington quarter: 3.617 dwt silver content
- 1964 Roosevelt dime: 1.447 dwt silver content
Gold coins: American Gold Eagles, Krugerrands, and other bullion coins are often referenced in pennyweights for smaller transactions:
- 1/10 oz Gold Eagle: 2 dwt
- 1/4 oz Gold Eagle: 5 dwt
- 1/2 oz Gold Eagle: 10 dwt
Counterfeit detection: Knowing the correct pennyweight of historic coins helps detect counterfeits: "This coin claims to be an 1893 Morgan silver dollar but weighs only 14.2 dwt instead of the correct 16.716 dwt—likely counterfeit."
5. Dental Alloys and Dentistry
Dental laboratories use pennyweights for precious metal dental alloys:
Gold crowns and bridges: Dental gold alloys (typically gold-palladium-silver combinations) are purchased and tracked in pennyweights: "Order 50 dwt of type III gold casting alloy for crown fabrication."
Scrap recovery: Dental offices collect scrap gold from old crowns, bridges, and orthodontic appliances, selling it by pennyweight to refiners: "Monthly dental scrap recovery: 18.5 dwt mixed gold alloys."
Material costs: Dental labs calculate restoration costs based on pennyweight requirements: "Three-unit bridge requires approximately 8 pennyweights of high-noble alloy, current cost $95/dwt = $760 materials."
6. Watchmaking and Repair
Watch repairmen and manufacturers use pennyweights for precious metal watch cases and components:
Gold watch cases: "18kt gold pocket watch case: 42 dwt" Solid gold bracelet links: "Replacement gold bracelet links: 1.2 dwt each" Vintage watch restoration: "Restore gold crown and stem: requires 0.8 dwt 14kt gold stock"
7. Hallmarking and Legal Compliance
Official assay offices and hallmarking authorities use pennyweights in legal documentation:
Fineness certification: British Hallmarking Act requires items over certain pennyweight thresholds be hallmarked:
- Gold: items over 0.5 dwt must be hallmarked
- Silver: items over 5 dwt must be hallmarked
- Platinum: items over 0.33 dwt must be hallmarked
Export documentation: Precious metals crossing international borders require customs declarations listing pennyweight and fineness: "Shipment: 1,450 dwt of 999 fine gold bullion."
Consumer protection: Trading standards enforce accurate weight declarations, with penalties for misrepresenting pennyweight on jewelry labels.
Additional Unit Information
About Kilogram (kg)
How much is 1 kilogram visually?
One kilogram is about the weight of a liter bottle of water or a small laptop.
Visual comparisons:
- 1 liter of water: Exactly 1 kg (at 4°C)
- Bag of sugar: Typically 1 kg or 2 kg
- Small laptop: 1-1.5 kg
- Two pineapples: About 1 kg total
- Medium-sized book: Approximately 1 kg
- Loaf of bread: About 0.5-0.8 kg (1 kg for larger loaves)
Body reference:
- For most people, 1 kg is slightly heavier than can be easily held in one hand for extended periods
- About 2-3% of average adult body weight
To remember: Picture a standard milk or water bottle (1 liter) - that's 1 kilogram.
How many pounds are in a kilogram?
One kilogram equals approximately 2.20462 pounds, commonly rounded to 2.2 pounds.
Exact conversion: 1 kilogram = 2.204622622 pounds
Practical conversions:
- 1 kg ≈ 2.2 lb
- 5 kg ≈ 11 lb
- 10 kg ≈ 22 lb
- 50 kg ≈ 110 lb
- 70 kg ≈ 154 lb
- 100 kg ≈ 220 lb
Reverse conversion (pounds to kilograms):
- 1 pound = 0.453592 kg (about 0.45 kg)
- 10 pounds ≈ 4.5 kg
- 100 pounds ≈ 45.4 kg
- 150 pounds ≈ 68 kg
- 200 pounds ≈ 90.7 kg
Quick mental math:
- Multiply kg by 2 and add 10% for rough estimate
- Example: 50 kg × 2 = 100, + 10% = 110 lb
Use our kg to pounds converter for accurate conversions.
What is the difference between kilogram and gram?
Kilogram (kg) is 1,000 times larger than gram (g).
The relationship:
- 1 kilogram = 1,000 grams
- 1 gram = 0.001 kilograms (or 1/1,000 kg)
Conversion:
- To convert kg to g: multiply by 1,000
- To convert g to kg: divide by 1,000
When to use which:
Use grams (g) for:
- Small quantities (< 1 kg)
- Food ingredients (200g flour, 500g meat)
- Precious metals (gold, silver by the gram)
- Medications (pills in mg or g)
- Postal items under 1 kg
Use kilograms (kg) for:
- Body weight
- Larger food packages
- Most everyday objects
- Shipping packages
- Sports equipment
Examples:
- Smartphone: 200 grams = 0.2 kg
- Laptop: 1,500 grams = 1.5 kg
- Bag of rice: 5,000 grams = 5 kg
- Person: 70,000 grams = 70 kg
Convert: kg to grams | grams to kg
Is the kilogram used in the United States?
Yes and no - it depends on the context.
Where kilograms ARE used in the US:
- Science and research: All scientific work
- Medicine: Drug dosing, patient weights in hospitals
- Manufacturing: Especially export products
- Athletics: Olympic sports, international competition
- Import/export: International trade
- Automotive: Vehicle specifications (increasingly)
- Pharmaceuticals: All measurements
- Military: NATO standardization
Where kilograms are NOT commonly used:
- Grocery stores (pounds, not kg)
- Body weight (people say pounds)
- Cooking (recipes use cups, ounces)
- Bathroom scales (typically show pounds)
- Everyday conversation
- Food packaging (labeled in oz, lb)
The dual system:
- US products often show both: "1 lb (454g)" or "Net Wt 16 oz (1 lb) 453g"
- Scientific calculators and medical equipment use kg
- US is officially metric but hasn't converted fully
Fun fact: US currency is metric (100 cents = 1 dollar), but few Americans realize this!
How many grams are in a kilogram?
There are exactly 1,000 grams (g) in one kilogram.
Why 1,000?: The prefix "kilo-" means 1,000.
Conversion:
- 1 kilogram (kg) = 1,000 grams (g)
- To convert kg to g: multiply by 1,000
- To convert g to kg: divide by 1,000
Examples:
- 0.5 kg = 500 grams
- 1.5 kg = 1,500 grams
- 2.75 kg = 2,750 grams
- 5 kg = 5,000 grams
- 10 kg = 10,000 grams
Remember: Move the decimal point three places:
- Kg → g: Move right (1.5 kg = 1,500 g)
- G → kg: Move left (1,500 g = 1.5 kg)
Common weights:
- Smartphone: 150-250 g = 0.15-0.25 kg
- Bag of sugar: 1,000 g = 1 kg
- Newborn baby: 3,000-4,000 g = 3-4 kg
Use our kg to grams converter for instant conversions.
How is the kilogram defined today?
Current Definition (since May 20, 2019): The kilogram is defined by fixing the numerical value of the Planck constant at exactly 6.62607015×10⁻³⁴ joule-seconds (J⋅s).
What this means:
- No longer based on a physical object (the old platinum-iridium cylinder)
- Based on a fundamental constant of quantum mechanics
- Can be reproduced in any properly equipped laboratory worldwide
- Uses a device called a "Kibble balance" (formerly watt balance)
- Incredibly stable and will never change
Why this definition?:
- Universal: The Planck constant is the same everywhere in the universe
- Reproducible: Any lab with the right equipment can measure it
- Permanent: Physical objects degrade; constants don't
- Precise: More accurate than artifact-based definition
How it works: A Kibble balance measures mass by balancing it against electromagnetic force. By fixing the Planck constant, the electromagnetic force precisely defines mass.
Historical evolution:
- 1795: Mass of 1 liter of water
- 1889: Physical prototype (Le Grand K)
- 2019: Planck constant (current definition)
Why it matters: This was the last SI base unit to be redefined based on fundamental constants, completing the modernization of the metric system.
What does "kg" stand for?
"kg" is the symbol for kilogram.
Breaking it down:
- kilo-: Greek prefix meaning 1,000
- gram: Base unit of mass in the metric system
- kilogram: Literally "1,000 grams"
Symbol rules:
- Always lowercase "k" (not "Kg" or "KG")
- Lowercase "g"
- No period after "kg"
- Space between number and symbol: "5 kg" (not "5kg")
Other kilo- units:
- kilometer (km) = 1,000 meters
- kilowatt (kW) = 1,000 watts
- kilojoule (kJ) = 1,000 joules
- kilobyte (kB or KB) = 1,000 bytes
Interesting fact: The kilogram is unique among SI base units because it already contains a prefix ("kilo-"). The base unit is actually the gram, but kilogram is the official SI base unit for mass.
How do you convert kilograms to ounces?
To convert kilograms to ounces, multiply by approximately 35.274.
Conversion formula: ounces = kilograms × 35.274
Examples:
- 1 kg = 35.3 ounces
- 0.5 kg = 17.6 ounces
- 2 kg = 70.5 ounces
- 5 kg = 176.4 ounces
- 10 kg = 352.7 ounces
Reverse conversion (ounces to kilograms):
- 1 ounce = 0.0283495 kg (about 28.35 grams)
- 16 ounces (1 pound) = 0.4536 kg
- 32 ounces = 0.907 kg
- 100 ounces = 2.835 kg
Why 35.274?
- 1 kg = 2.20462 pounds
- 1 pound = 16 ounces
- 2.20462 × 16 = 35.274 ounces per kilogram
Quick mental math:
- 1 kg ≈ 35 oz (close enough for estimates)
- 0.5 kg ≈ 18 oz (just over 1 pound)
Use our kg to ounces converter for precise conversions.
What is 70 kg in pounds?
70 kilograms = 154.32 pounds (commonly rounded to 154 pounds).
Calculation: 70 kg × 2.20462 lb/kg = 154.32 lb
Context:
- Average adult: 70 kg is a typical weight for an average-height adult
- Healthy weight: For a 5'10" (178 cm) person, 70 kg is within healthy range
- Athletes: Many athletes in various sports weigh around 70 kg
Nearby conversions:
- 65 kg = 143 lb
- 70 kg = 154 lb
- 75 kg = 165 lb
- 80 kg = 176 lb
Body weight ranges (approximate):
- 50 kg = 110 lb (petite adult)
- 60 kg = 132 lb (average woman)
- 70 kg = 154 lb (average man)
- 80 kg = 176 lb (athletic/large build)
- 90 kg = 198 lb (large adult)
- 100 kg = 220 lb (very large adult)
Convert any weight: kg to pounds converter
How much does a kilogram weigh on Earth?
On Earth, 1 kilogram has a weight of approximately 9.8 newtons (N) at sea level.
Important distinction:
- Mass: 1 kilogram (constant everywhere)
- Weight: Force due to gravity = mass × gravitational acceleration
- On Earth: Weight (N) = 1 kg × 9.8 m/s² = 9.8 N
What this means:
- Your mass stays 1 kg everywhere
- Your weight changes based on gravitational strength
- On Earth, we feel this as "weight"
Weight on other celestial bodies (for 1 kg mass):
- Moon: 1.6 N (about 1/6 of Earth)
- Mars: 3.7 N (about 3/8 of Earth)
- Jupiter: 24.8 N (about 2.5× Earth)
- Sun: 274 N (about 28× Earth)
- International Space Station: ~8.7 N (microgravity, but not zero)
Why we say "weight in kilograms": In everyday language, "weight" means mass. Technically incorrect, but universally understood. Scientists use "mass in kilograms" and "weight in newtons" for precision.
Remember: Your bathroom scale measures mass (kg), not weight (newtons), but we casually call it "weight."
What is a metric ton vs kilogram?
Metric ton (also called tonne) = 1,000 kilograms.
The relationship:
- 1 metric ton = 1,000 kg
- 1 kilogram = 0.001 metric tons
Symbols:
- Metric ton: t or MT or tonne
- Kilogram: kg
When to use which:
Use kilograms (kg) for:
- Individual weights (< 1,000 kg)
- Body weight, packages, products
- Most everyday measurements
Use metric tons (tonnes) for:
- Heavy vehicles (cars, trucks)
- Industrial materials
- Bulk commodities
- Cargo shipping
- Agricultural yields
Examples:
- Small car: 1,000-1,500 kg = 1-1.5 metric tons
- Elephant: 5,000 kg = 5 metric tons
- Shipping container: 20,000-30,000 kg = 20-30 metric tons
- Wheat harvest: 100,000 kg = 100 metric tons
Confusion alert:
- Metric ton (1,000 kg) ≠ US ton (2,000 lb = 907 kg)
- Metric ton (1,000 kg) ≠ UK ton (2,240 lb = 1,016 kg)
- Always specify which ton!
Convert: kg to metric tons | metric tons to kg
About Pennyweight (dwt)
How many pennyweights are in a troy ounce?
Answer: Exactly 20 pennyweights = 1 troy ounce
This is the fundamental relationship in the troy weight system. Since 1 troy ounce = 31.1035 grams and 1 pennyweight = 1.55517384 grams:
31.1035 g ÷ 1.55517384 g = 20 dwt
This makes price calculations straightforward: if gold is $2,000/troy ounce, it's exactly $100/pennyweight ($2,000 ÷ 20 = $100).
How many grains are in a pennyweight?
Answer: Exactly 24 grains = 1 pennyweight
The grain is the smallest troy weight unit, and the pennyweight was historically defined as 24 grains. This relationship has remained constant since medieval standardization:
1 dwt = 24 gr = 1.55517384 g
Since 1 grain = 64.79891 mg: 24 grains × 64.79891 mg = 1,555.17384 mg = 1.55517384 g
How many grams are in a pennyweight?
Answer: Exactly 1.55517384 grams = 1 pennyweight
This exact definition comes from the 1959 international yard and pound agreement, which defined the grain as exactly 64.79891 milligrams. Since 1 pennyweight = 24 grains:
1 dwt = 24 × 64.79891 mg = 1,555.17384 mg = 1.55517384 g (exact)
For practical purposes, you can approximate 1 dwt ≈ 1.56 g, but official transactions use the exact value.
Why is it called a "pennyweight"?
Answer: It originally represented the weight of one silver penny in medieval England
During the Anglo-Saxon period and continuing through the Norman conquest, English silver pennies were standardized to weigh exactly one pennyweight each. This created an elegant system where:
- 1 penny (coin) = 1 pennyweight (weight) of silver
- 240 pennies = 1 pound sterling = 1 troy pound of silver
This direct correspondence between monetary value and precious metal weight lasted for centuries and gave the unit its name. The abbreviation "dwt" comes from "denarius weight" (denarius being the Latin word for penny).
Is the pennyweight still used today?
Answer: Yes, the pennyweight remains the standard working unit for jewelers, goldsmiths, and precious metals dealers worldwide
Despite metrication in many countries, the pennyweight persists because:
- International trade: Precious metals are traded globally in troy ounces/pennyweights
- Industry infrastructure: Scales, pricing systems, and reference materials use troy units
- Practical size: Pennyweights provide appropriate precision for jewelry (more precise than ounces, less unwieldy than grains)
- Legal requirements: Many jurisdictions mandate troy weights for bullion and hallmarking
The London Bullion Market Association (LBMA), which sets global precious metals standards, continues to use troy ounces and pennyweights, ensuring the unit's ongoing relevance.
What's the difference between pennyweight and carat?
Answer: Pennyweight measures the weight of precious METALS, while carat measures the weight of GEMSTONES (and separately, the purity of gold)
This is a common source of confusion because "carat" has two different meanings:
1. Metric carat (ct) - Gemstone weight:
- 1 carat = 200 milligrams = 0.2 grams
- Used exclusively for gemstones (diamonds, rubies, sapphires, etc.)
- 1 pennyweight = 7.776 carats (though you wouldn't measure metal in carats)
2. Karat (kt or K) - Gold purity:
- Measures gold purity out of 24 parts
- 24kt = pure gold (99.9%)
- 18kt = 18/24 = 75% gold
- 14kt = 14/24 = 58.3% gold
- NOT a weight unit at all
Pennyweight (dwt) - Metal weight:
- 1 dwt = 1.555 grams
- Used for precious metals (gold, silver, platinum)
- A completely separate measurement from both carat meanings
Example: An "18kt gold ring weighing 5 pennyweights with a 1-carat diamond" means:
- Ring metal: 18-karat purity (75% pure gold)
- Ring weight: 5 dwt (7.78 g)
- Diamond weight: 1 carat (0.2 g)
How do I convert pennyweights to grams?
Answer: Multiply pennyweights by 1.55517384 (exact) or 1.556 (approximate)
Exact formula: grams = pennyweights × 1.55517384
Examples:
- 5 dwt = 5 × 1.55517384 = 7.7759 g
- 10 dwt = 10 × 1.55517384 = 15.5517 g
- 20 dwt = 20 × 1.55517384 = 31.1035 g (1 troy ounce)
Quick approximation: For mental math, use 1.56:
- 5 dwt ≈ 5 × 1.56 = 7.8 g (close enough for estimates)
Reverse conversion (grams to pennyweights): Divide grams by 1.55517384, or multiply by 0.643:
- 10 g ÷ 1.55517384 = 6.43 dwt
Can I use a regular scale to measure pennyweights?
Answer: No, you need a scale that displays troy units or precise gram measurements that you can convert
Most household scales show avoirdupois ounces/pounds or grams, not troy pennyweights. For accurate precious metals measurement:
Option 1: Troy weight scale
- Purchase a jeweler's scale that displays troy ounces subdivided into pennyweights
- Professional models show "oz dwt" format (e.g., "1 oz 15 dwt")
- Precision typically 0.01 dwt (0.0155 g)
Option 2: Gram scale with conversion
- Use a precise gram scale (0.01 g accuracy minimum)
- Measure in grams and divide by 1.555 to get pennyweights
- Example: 7.78 g ÷ 1.555 = 5.00 dwt
Not recommended: Regular kitchen scales or bathroom scales lack sufficient precision for pennyweight accuracy.
Professional standards: Jewelers and precious metals dealers use scales certified for troy weight accuracy, often calibrated annually to ensure compliance with trading standards regulations.
How much is a pennyweight of gold worth?
Answer: Divide the current gold price per troy ounce by 20
Gold prices are quoted in dollars per troy ounce. Since 1 troy ounce = 20 pennyweights:
Price per dwt = Price per oz t ÷ 20
Examples (using approximate gold prices):
- Gold at $2,000/oz → $100/dwt ($2,000 ÷ 20)
- Gold at $1,800/oz → $90/dwt ($1,800 ÷ 20)
- Gold at $2,200/oz → $110/dwt ($2,200 ÷ 20)
IMPORTANT: This is for pure gold (24kt). Most jewelry is alloyed:
14kt gold (58.3% pure):
- If pure gold = $100/dwt
- 14kt gold = $100 × 0.583 = $58.30/dwt
18kt gold (75% pure):
- If pure gold = $100/dwt
- 18kt gold = $100 × 0.75 = $75/dwt
Current prices: Check live gold prices at kitco.com, bullionvault.com, or your local precious metals dealer, then divide by 20 for per-pennyweight pricing.
What items typically weigh one pennyweight?
Answer: Small gold earrings, simple pendants, or single ring settings
Examples of ~1 dwt items:
- Simple gold stud earrings (pair): 0.8-1.5 dwt
- Small gold charm: 0.5-1.2 dwt
- Thin gold chain link: 0.3-0.8 dwt per link
- Single prong setting for gemstone: 0.6-1.0 dwt
- Gold nose ring/stud: 0.2-0.5 dwt
For reference:
- Medieval silver penny: exactly 1 dwt (by definition)
- Modern nickel (5¢ coin): ~32 dwt (5 g) - but not silver
- Paperclip: ~5-6 dwt (0.8 g)
Heavier items for comparison:
- Wedding ring: 3-6 dwt
- Gold chain necklace: 5-15 dwt
- Class ring: 12-20 dwt
- 1 troy ounce gold coin: 20 dwt
Why use pennyweights instead of grams for jewelry?
Answer: Industry tradition, international trade standards, and practical calculation convenience
Historical continuity: The precious metals industry has used troy weights for over 700 years. Switching to metric would require:
- Replacing millions of troy scales
- Retraining entire industry workforce
- Revising international trade agreements
- Updating hallmarking regulations in dozens of countries
International standardization: The London Bullion Market Association (LBMA) sets global precious metals trading standards in troy ounces. Since jewelry trades internationally, using consistent units (pennyweights/troy ounces) simplifies transactions.
Practical precision: Pennyweights provide appropriate precision:
- Too precise: grains (24 grains = 1 dwt means many small fractions)
- Too coarse: troy ounces (typical ring is 0.15-0.30 oz = awkward decimals)
- Just right: pennyweights (typical ring is 3-6 dwt = clean numbers)
Mental math ease: The 20:1 ratio (20 dwt = 1 oz t) makes price calculations simple:
- Gold at $2,000/oz = $100/dwt (divide by 20)
- A 5 dwt item = $500 worth of gold (multiply by 100)
Legal requirements: Many jurisdictions legally mandate troy weights for precious metals hallmarking and trading, making pennyweights the regulatory standard.
Are pennyweights used outside of precious metals?
Answer: No, pennyweights are exclusively used for precious metals, gemstone settings, and related industries
Where pennyweights ARE used:
- Gold, silver, platinum jewelry manufacturing
- Precious metals trading and refining
- Coin collecting (numismatics)
- Dental gold alloys
- Watchmaking (gold/platinum cases)
- Bullion buying and selling
- Hallmarking and assay offices
Where pennyweights are NOT used:
- General commerce (uses avoirdupois ounces/pounds or grams/kilograms)
- Food and cooking (ounces, pounds, grams)
- Body weight (pounds or kilograms)
- Gemstones themselves (use metric carats: 1 ct = 0.2 g)
- Pharmaceuticals (uses grains, grams, milligrams, but not pennyweights)
- Scientific measurements (uses metric system exclusively)
The exception: Grains (the smallest troy unit) ARE used in both troy weight (precious metals) and pharmaceutical/bullet weight measurements, but pennyweights appear only in troy contexts.
Conversion Table: Kilogram to Pennyweight
| Kilogram (kg) | Pennyweight (dwt) |
|---|---|
| 0.5 | 321.508 |
| 1 | 643.015 |
| 1.5 | 964.522 |
| 2 | 1,286.03 |
| 5 | 3,215.075 |
| 10 | 6,430.149 |
| 25 | 16,075.373 |
| 50 | 32,150.747 |
| 100 | 64,301.493 |
| 250 | 160,753.733 |
| 500 | 321,507.466 |
| 1,000 | 643,014.931 |
People Also Ask
How do I convert Kilogram to Pennyweight?
To convert Kilogram to Pennyweight, enter the value in Kilogram in the calculator above. The conversion will happen automatically. Use our free online converter for instant and accurate results. You can also visit our weight converter page to convert between other units in this category.
Learn more →What is the conversion factor from Kilogram to Pennyweight?
The conversion factor depends on the specific relationship between Kilogram and Pennyweight. You can find the exact conversion formula and factor on this page. Our calculator handles all calculations automatically. See the conversion table above for common values.
Can I convert Pennyweight back to Kilogram?
Yes! You can easily convert Pennyweight back to Kilogram by using the swap button (⇌) in the calculator above, or by visiting our Pennyweight to Kilogram converter page. You can also explore other weight conversions on our category page.
Learn more →What are common uses for Kilogram and Pennyweight?
Kilogram and Pennyweight are both standard units used in weight measurements. They are commonly used in various applications including engineering, construction, cooking, and scientific research. Browse our weight converter for more conversion options.
For more weight conversion questions, visit our FAQ page or explore our conversion guides.
Helpful Conversion Guides
Learn more about unit conversion with our comprehensive guides:
📚 How to Convert Units
Step-by-step guide to unit conversion with practical examples.
🔢 Conversion Formulas
Essential formulas for weight and other conversions.
⚖️ Metric vs Imperial
Understand the differences between measurement systems.
⚠️ Common Mistakes
Learn about frequent errors and how to avoid them.
All Weight Conversions
Other Weight Units and Conversions
Explore other weight units and their conversion options:
- Gram (g) • Kilogram to Gram
- Milligram (mg) • Kilogram to Milligram
- Pound (lb) • Kilogram to Pound
- Ounce (oz) • Kilogram to Ounce
- Stone (st) • Kilogram to Stone
- Ton (metric) (t) • Kilogram to Ton (metric)
- Ton (US) (ton) • Kilogram to Ton (US)
- Ton (UK) (long ton) • Kilogram to Ton (UK)
- Microgram (µg) • Kilogram to Microgram
- Carat (ct) • Kilogram to Carat
Verified Against Authority Standards
All conversion formulas have been verified against international standards and authoritative sources to ensure maximum accuracy and reliability.
National Institute of Standards and Technology — US standards for weight and mass measurements
International Organization for Standardization — International standard for mechanics quantities
Last verified: December 3, 2025