Kilogram to Stone Converter
Convert kilograms to stones with our free online weight converter.
Quick Answer
1 Kilogram = 0.157473 stones
Formula: Kilogram × conversion factor = Stone
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 Stone Calculator
How to Use the Kilogram to Stone Calculator:
- Enter the value you want to convert in the 'From' field (Kilogram).
- The converted value in Stone 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 Stone: Step-by-Step Guide
Converting Kilogram to Stone involves multiplying the value by a specific conversion factor, as shown in the formula below.
Formula:
1 Kilogram = 0.157473 stonesExample Calculation:
Convert 5 kilograms: 5 × 0.157473 = 0.787365 stones
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 Stone?
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
1 stone = 14 avoirdupois pounds (lb) = 6.35029318 kilograms (kg) EXACT
The stone (symbol: st) is a unit of mass in the Imperial system, legally defined in terms of pounds, which are themselves defined in terms of kilograms. The exact conversion is:
1 pound = 0.45359237 kilograms (international definition, 1959)
1 stone = 14 × 0.45359237 kg = 6.35029318 kg
Stone and Pounds Notation
The stone is almost never used alone for body weight. Instead, it's combined with additional pounds:
Format: "X stone Y pounds" or "X st Y lb"
Examples:
- 10 st 0 lb = 10 stone exactly = 140 lb = 63.5 kg
- 10 st 7 lb = 10 stone + 7 pounds = 147 lb = 66.7 kg
- 12 st 3 lb = 12 stone + 3 pounds = 171 lb = 77.6 kg
Why this format? It provides precision without unwieldy decimal places. Saying "10.5 stone" is rare—people say "10 stone 7" instead (10 stone + 7 pounds = 10.5 stone).
Stone vs. Kilogram vs. Pound
Three systems for measuring body weight:
| System | Unit | Used In | Precision | |-----------|----------|-------------|---------------| | Imperial (UK) | Stone + Pounds | UK, Ireland | "11 st 7 lb" (161 lb) | | Imperial (US) | Pounds only | United States, Canada | "161 lb" | | Metric | Kilograms | Most of the world | "73 kg" |
Cultural difference:
- Americans say "I weigh 161 pounds"
- British say "I weigh 11 stone 7" (rarely "161 pounds")
- Europeans say "I weigh 73 kilograms"
Why 14 Pounds?
The number 14 has no scientific basis—it's purely historical. Medieval England used base-12 counting (duodecimal) for some systems:
- 12 inches = 1 foot
- 12 pence = 1 shilling (pre-1971)
- But 14 pounds = 1 stone (not 12!)
Theory: The 14-pound wool stone emerged from trade practices. A "sack of wool" weighed 364 pounds = 26 stones (26 × 14 = 364), a convenient round number for taxation and commerce.
Note: The Kilogram is part of the metric (SI) system, primarily used globally in science and trade. The Stone belongs to the imperial/US customary system.
History of the Kilogram and Stone
-
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.
-
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.
-
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.
-
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 and Medieval Origins (Pre-1300)
The concept of standardized stones: Before precise metallic weights, communities used stones as trade counterweights. A merchant would keep a reference stone in the marketplace, verified by local authorities, against which goods were weighed.
Advantages:
- Durability: Stones don't corrode or wear like metal
- Availability: Every village had stones
- Tamper-resistance: Hard to secretly shave weight off a stone
Problem: Every region had different stones! The "stone of wool" in Yorkshire differed from the "stone of wool" in Kent.
Medieval Standardization Attempts (1300-1824)
Edward III's wool stone (1340): King Edward III standardized the wool stone at 14 pounds as part of regulating the lucrative wool trade (England's economic backbone in the Middle Ages). The "sack of wool" was defined as 364 pounds = 26 stones.
Commodity-specific stones: Different goods had different stone weights:
| Commodity | Stone Weight | Reasoning | |--------------|-----------------|---------------| | Wool | 14 lb (6.35 kg) | Trade standard | | Meat | 8 lb (3.63 kg) | Butcher's stone | | Glass | 5 lb (2.27 kg) | Fragile goods | | Cheese | 16 lb (7.26 kg) | Agricultural products | | Iron | Variable (8-15 lb) | Regional differences |
Why different weights? Practical reasons:
- Heavy commodities (iron, lead): Smaller stone weight made counting easier
- Light, valuable goods (wool, spices): Larger stone weight reduced fractions
- Tradition: Each guild jealously guarded its customary weights
The Weights and Measures Act 1824
The problem: By 1800, Britain had dozens of incompatible stone definitions, creating chaos in trade and taxation.
The solution: The 1824 Act standardized British weights and measures:
- 14 pounds = 1 stone (for general use, not tied to specific commodities)
- Stone officially defined in relation to the pound
- Commodity-specific stones discouraged (but not banned)
Imperial standardization: The Act also defined:
- 1 pound = 7,000 grains
- 16 ounces = 1 pound
- 14 pounds = 1 stone
- 8 stone = 1 hundredweight (112 pounds)
- 20 hundredweight = 1 ton (2,240 pounds)
Body weight adoption: The Victorian era (1837-1901) saw the stone become the standard for human weighing. Bathroom scales, medical records, and public health data used stones and pounds.
Metrication and Persistence (1965-Present)
The Weights and Measures Act 1965: The UK officially adopted the metric system, making kilograms the legal unit for trade. However, the Act exempted personal weighing—bathroom scales could continue showing stones.
Why the exemption?
- Cultural resistance: Brits refused to abandon stones for body weight
- Economic lobbying: Scale manufacturers didn't want to retool
- Medical inertia: NHS records already used stones; conversion would be costly
The result: 60+ years later, the stone persists:
- Bathroom scales: Default to stones in the UK (even modern digital ones)
- NHS medical records: Still record patient weight in stones/pounds
- Weight loss programs: Slimming World, Weight Watchers UK use stones
- Media: British newspapers report celebrity weight in stones
- Sports: Boxing, horse racing, rowing use stones for weight classes
Ireland's experience: Ireland officially adopted metric units in 2005, but the stone remains common for body weight, especially among older generations.
Generational divide:
- Older Brits (60+): Think exclusively in stones
- Middle-aged (30-60): Bilingual (stones and kilograms)
- Younger (<30): Increasingly use kilograms, but still understand stones
Cultural Tenacity
The stone is the most persistent Imperial unit in British daily life, outlasting:
- Fahrenheit: Replaced by Celsius (weather, ovens)
- Inches/feet for height: Partially replaced by metres (though feet still common)
- Pints: Milk sold in litres (though beer still sold in pints!)
- Miles: Road signs still use miles (the UK never fully switched)
Why the stone survives:
- Emotional connection: Body weight is personal; changing units feels invasive
- Convenient range: For adults, weight is 8-20 stones (easy to remember vs. 50-127 kg)
- Medical exemption: Doctors use stones, so patients use stones
- Social reinforcement: Everyone around you uses stones, so you do too
Common Uses and Applications: kilograms vs stones
Explore the typical applications for both Kilogram (metric) and Stone (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 stones
1. Body Weight Measurement
The stone is the unit for body weight in the UK and Ireland.
Bathroom scales:
- Display: "11 st 7 lb" (digital) or analog dial with stone markings
- Dual units: Many scales toggle between st/lb and kg
- Default: Stones for UK-sold scales, even from international brands
Weighing yourself:
- British: "I'm 12 stone 3"
- American: "I'm 171 pounds"
- European: "I'm 78 kilograms"
Weight goals:
- "I want to lose a stone" = 14-pound goal
- "I'm aiming for 10 stone" = target weight
- "I've gained half a stone" = 7-pound increase
2. Medical and Healthcare
NHS patient records: British hospitals and GPs record weight in stones/pounds (with kg conversion).
Medical forms:
- Pre-op questionnaires: "Weight: __ st __ lb"
- Prescription dosing: Sometimes based on weight (converted to kg for calculations)
- Anesthesia planning: Weight in stones converted to kg for drug dosages
Maternity care:
- Booking appointment: "What was your pre-pregnancy weight?" (stones)
- Pregnancy weight tracking: "You've gained 2 stone, which is healthy"
- Post-natal: "Most women lose 1-2 stone in the first weeks"
Mental health context: Eating disorder treatment tracks weight changes in stones (e.g., anorexia recovery: "gained 1 stone to 7 stone 10").
3. Weight Loss and Fitness
Slimming clubs:
- Slimming World, Weight Watchers UK: Weigh-ins in stones
- Awards: "Half-stone hero," "Stone club," "3-stone milestone"
- Targets: "Lose 10% of body weight" (e.g., 1.5 stone from 15 stone start)
Fitness apps (UK versions):
- MyFitnessPal UK: Input weight in stones
- Fitbit/Garmin: UK users set goals in stones
- Weight tracking graphs: Y-axis shows stones, not kg
Personal trainers: British trainers discuss client progress in stones: "You've dropped from 14 stone to 12 stone 8—fantastic!"
4. Sports Weight Classes
Boxing: British boxing traditionally used stones for weight classes (now officially kilograms, but stones still common in commentary).
Horse racing:
- Jockey weights: Includes jockey + saddle + lead weights to meet required "riding weight"
- Handicapping: Horses carry different weights (in stones) to equalize competition
- Penalties: "Carrying 9 stone 7" vs. "Carrying 10 stone" affects race outcomes
Rowing: Lightweight rowers must weigh under certain stone limits (now metric, but historically stones).
5. Everyday Conversation
The stone pervades British informal speech:
Common phrases:
- "I'm 11 stone, give or take" = approximate weight
- "She must be 10 stone soaking wet" = very light
- "He's put on a stone since Christmas" = seasonal weight gain
- "I haven't been 9 stone since I was 15!" = nostalgic reference
Social etiquette:
- It's impolite to ask someone's weight directly, but acceptable to discuss your own
- Women might say "I'm trying to get back to 9 stone" (goal weight)
6. Media and Entertainment
British TV shows:
- Reality TV: "Love Island" contestants' weights discussed in tabloids (stones)
- Medical shows: "Embarrassing Bodies" references patient weight in stones
- Game shows: "The Biggest Loser UK" tracked loss in stones
Newspapers and magazines:
- Celebrity weight speculation: "Has she lost 2 stone?"
- Health articles: "How to lose half a stone by summer"
- Success stories: "I lost 8 stone and transformed my life!"
7. Historical and Cultural References
Literature: Victorian novels reference weight in stones:
- Dickens, Austen rarely mention specific weights (impolite)
- 20th-century literature: "She was a strapping girl of 12 stone"
British humor: Comedians joke about weight in stones:
- "I'm not overweight, I'm just undertall for my 14 stone!"
Generational markers:
- Older Brits: "When I got married, I was 8 stone"
- Modern comparison: "That's only 112 pounds—too thin by today's standards!"
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 Stone (st)
1. How many pounds are in a stone?
Exactly 14 pounds.
This is a defined constant. There are no regional variations—1 stone always equals 14 pounds in any context.
Calculation examples:
- 5 stone = 5 × 14 = 70 pounds
- 12 stone = 12 × 14 = 168 pounds
- 0.5 stone = 0.5 × 14 = 7 pounds
2. Is the stone used outside the UK and Ireland?
Rarely. The stone is almost exclusive to the UK and Ireland.
Usage by country:
- UK: Dominant for body weight (even with official metrication)
- Ireland: Common, especially among older generations
- Canada, Australia, New Zealand: Not used (fully metric)
- United States: Not used (pounds only)
- Rest of world: Not used (metric)
Exception: British expats abroad sometimes use stones, and international weight loss forums may reference stones when discussing UK participants.
3. Why is it called a stone?
Historical practice: Actual stones were used as standardized weights in medieval markets.
How it worked:
- A community selected a reference stone of agreed weight
- The stone was kept in the marketplace (sometimes literally built into a wall)
- Merchants used the reference stone on balance scales to verify weights
- Different stones existed for different commodities (wool stone, meat stone, etc.)
Modern name: The unit name "stone" is a fossil of this practice, long after actual stones stopped being used.
4. How do you convert stone to kilograms?
Formula:
Kilograms = Stone × 6.35029318
Quick approximation:
Kilograms ≈ Stone × 6.35 (good to 3 decimal places)
Examples:
- 10 stone × 6.35 = 63.5 kg
- 12 stone × 6.35 = 76.2 kg
- 15 stone × 6.35 = 95.25 kg
Online tools: Most conversion sites and apps include stone ↔ kilogram calculators.
5. How do British people talk about their weight?
Typical format: "I'm X stone Y pounds" or "I'm X stone Y"
Examples:
- "I'm 11 stone 7" = 11 stone + 7 pounds = 161 lb = 73 kg
- "I'm just over 12 stone" = slightly more than 168 lb
- "I'm nearly 10 stone" = approaching 140 lb
Rarely said:
- "I'm 11.5 stone" (uncommon—people say "11 stone 7" instead)
- "I'm 161 pounds" (too American—Brits don't think in pounds alone)
- "I'm 73 kilograms" (used by younger generations, but less common)
Conversational weight: Discussing weight is somewhat taboo, so people often avoid specifics: "I need to lose a bit of weight" rather than "I need to drop from 13 to 11 stone."
6. Do British bathroom scales show kilograms?
Yes, most modern scales show both.
Typical features:
- Default: Stones and pounds (st/lb)
- Toggle button: Switch to kilograms
- Dual display: Some show both simultaneously
Older scales: Analog scales from before 2000 often show stones only.
Buying scales in the UK: Even international brands (Fitbit, Garmin) sell UK-specific versions that default to stones.
7. Will the UK ever stop using stones?
Unlikely in the near future.
Reasons for persistence:
- Cultural attachment: Body weight is personal; people resist change
- Legal exemption: Personal weighing scales exempt from trade regulations
- NHS inertia: Changing medical records costly
- Generational use: Older generations use stones exclusively
- No enforcement: No push to mandate kilograms for personal use
Trend: Younger Brits (under 30) increasingly use kilograms, especially those who travel or use fitness apps with international audiences. However, the stone will likely persist for decades among older populations.
Comparison: Similar to Fahrenheit in the US—officially discouraged but culturally entrenched.
8. What is a "half stone"?
Half stone = 7 pounds = 3.175 kg
Usage:
- Weight loss: "I've lost half a stone" = 7 lb loss
- Weight gain: "I've put on half a stone over Christmas" = 7 lb gain
- Milestones: "Half-stone club" in weight loss programs
Why significant? Half a stone is a noticeable weight change—enough to affect how clothes fit and how you feel, but achievable in 3-7 weeks of dieting (at 1-2 lb/week loss).
9. How do you write stone and pounds?
Common formats:
Formal:
- "11 stone 7 pounds"
- "11 st 7 lb"
Informal:
- "11 stone 7"
- "11st 7lb" (no spaces)
- "11-7" (very casual, context-dependent)
Avoid:
- "11.7 stone" (ambiguous—could mean 11 stone 7 lb or 11 stone 9.8 lb)
- "11/7 st" (confusing notation)
Medical records: NHS typically uses "st/lb" format: "Patient weight: 12 st 3 lb"
10. Why do Americans not use stone?
The United States never adopted the stone for body weight.
Historical reasons:
- Colonial divergence: By the time the stone standardized in Britain (1824), the US had already established pounds as the body weight unit
- Decimal preference: Americans favored simpler base-10 systems where possible
- No cultural push: No equivalent to UK's Victorian-era adoption of stones for weighing people
Result: Americans think in pounds only:
- "I weigh 180 pounds" (no stones)
- Weight loss: "I lost 30 pounds" (not "2 stone 2 pounds")
Canadian note: Canada officially metricated in the 1970s and uses kilograms, not stones or pounds (though older Canadians may still think in pounds).
11. Is stone a legal unit?
Yes, in the UK and Ireland, but with restrictions.
Legal status:
- Personal use: Fully legal (bathroom scales, self-weighing)
- Trade: Must use metric (kilograms) for selling goods by weight
- Medical: Allowed in patient records (NHS uses stones)
Weights and Measures Act: Kilograms are the legal unit for commerce, but stones remain legal for "non-trade" purposes (personal weighing, medical records).
Comparison: Similar to miles on UK road signs—officially metric, but exceptions preserve traditional units in specific contexts.
12. How much is a stone in other historical weight units?
Stone in troy and apothecary systems:
Troy weight (precious metals):
- 1 stone (avoirdupois) = 14 pounds (avoirdupois)
- 1 pound (avoirdupois) = 7,000 grains
- 1 stone = 98,000 grains (troy)
- 1 troy pound = 5,760 grains
- 1 stone ≈ 17.01 troy pounds
Apothecaries' weight (pharmacy):
- Same grain as troy and avoirdupois (64.79891 mg)
- 1 stone = 98,000 grains (apothecaries')
Why this matters: Historically, pharmacists used apothecaries' weights, so understanding stone conversions was important for dosing medicines based on body weight.
Conversion Table: Kilogram to Stone
| Kilogram (kg) | Stone (st) |
|---|---|
| 0.5 | 0.079 |
| 1 | 0.158 |
| 1.5 | 0.236 |
| 2 | 0.315 |
| 5 | 0.787 |
| 10 | 1.575 |
| 25 | 3.937 |
| 50 | 7.874 |
| 100 | 15.747 |
| 250 | 39.368 |
| 500 | 78.737 |
| 1,000 | 157.473 |
People Also Ask
How do I convert Kilogram to Stone?
To convert Kilogram to Stone, 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 Stone?
The conversion factor depends on the specific relationship between Kilogram and Stone. 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 Stone back to Kilogram?
Yes! You can easily convert Stone back to Kilogram by using the swap button (⇌) in the calculator above, or by visiting our Stone to Kilogram converter page. You can also explore other weight conversions on our category page.
Learn more →What are common uses for Kilogram and Stone?
Kilogram and Stone 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
- 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
- Slug (sl) • Kilogram to Slug
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