Grain to Pound Converter
Convert grains to pounds with our free online weight converter.
Quick Answer
1 Grain = 0.000143 pounds
Formula: Grain × conversion factor = Pound
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.
Grain to Pound Calculator
How to Use the Grain to Pound Calculator:
- Enter the value you want to convert in the 'From' field (Grain).
- The converted value in Pound 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 Grain to Pound: Step-by-Step Guide
Converting Grain to Pound involves multiplying the value by a specific conversion factor, as shown in the formula below.
Formula:
1 Grain = 0.000142857 poundsExample Calculation:
Convert 5 grains: 5 × 0.000142857 = 0.000714285 pounds
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 Grain and a Pound?
1 grain = 64.79891 milligrams (mg) = 0.06479891 grams (g) EXACT
The grain (symbol: gr) is a unit of mass legally defined since 1959 as exactly 64.79891 milligrams. It is the smallest and oldest unit in the traditional English measurement systems.
Grain in Three Weight Systems
The grain is unique—it's the only unit shared identically across three different weight systems:
| System | Use | Grain Relationships | |-----------|---------|------------------------| | Avoirdupois | General commerce, bullets | 437.5 gr = 1 oz; 7,000 gr = 1 lb | | Troy | Precious metals, gemstones | 480 gr = 1 oz troy; 5,760 gr = 1 lb troy | | Apothecaries' | Pharmacy (historical) | 480 gr = 1 oz apoth; 5,760 gr = 1 lb apoth |
Why this matters: The grain serves as the common denominator linking these systems. It's the conversion bridge between everyday weights and specialized applications.
The Barleycorn Origin
Historical basis: The grain was originally defined as the weight of a single grain of barley taken from the middle of the ear (not from the ends, which are lighter).
Remarkably consistent: Medieval experiments showed barleycorns have remarkably uniform mass:
- Average: 64-66 milligrams
- Modern definition: 64.79891 mg
- Variance: Only ~2-3% across different barley varieties
Length connection: King Edward I's statute (13th century) also defined 1 inch = 3 barleycorns laid end-to-end. Thus, the barleycorn defined both length and weight!
Metric Equivalents
Precise conversion:
1 grain = 64.79891 milligrams (EXACT, since 1959)
Common approximations:
1 grain ≈ 0.0648 grams (rounded)
1 grain ≈ 65 milligrams (rough)
15.43 grains ≈ 1 gram (useful for quick conversions)
Why 64.79891 mg? This exact value comes from the 1959 international yard and pound agreement:
- 1 pound = 0.45359237 kg (defined)
- 1 grain = 1/7000 pound
- 1 grain = 0.45359237 ÷ 7000 = 0.00006479891 kg = 64.79891 mg
The pound is a unit of mass in the British imperial and United States customary systems of measurement. Since the international yard and pound agreement of 1959, one pound has been defined as exactly 0.45359237 kilograms. This makes the pound equal to precisely 16 ounces, 7,000 grains, or 453.59237 grams.
The pound is denoted by the symbol lb (from the Latin libra, meaning balance or scales) or sometimes lbs for plural, though technically "lb" serves both singular and plural. In commercial contexts, you'll see prices as "$/lb" (dollars per pound) or weights as "5 lb bag."
Unlike the metric system where weight relationships are decimal (1,000 grams = 1 kilogram), the pound uses the relationship of 16 ounces to 1 pound. This fractional system reflects historical divisions: 1 pound = 16 ounces = 256 drams = 7,000 grains, with each division serving practical purposes in trade and measurement.
Note: The Grain is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Pound belongs to the imperial/US customary system.
History of the Grain and Pound
Ancient Origins (3000 BCE - 500 CE)
Mesopotamian seeds: The earliest weight systems in Sumer and Babylon (circa 3000-2000 BCE) used seeds as counterweights:
- Barleycorns: Small weights
- Wheat grains: Alternative standard
- Carob seeds: Larger weights (origin of "carat" for gemstones)
Why seeds? Seeds have several advantages as weights:
- Availability: Every agricultural community had grain
- Uniformity: Grains from the same species have consistent mass
- Portability: Easy to carry, store, and count
- Natural standard: Self-evident, no authority needed to verify
Babylonian system:
- 180 barleycorns = 1 shekel (~8.4 grams)
- Shekels formed the basis for Mesopotamian commerce
Egyptian weights: Ancient Egypt used wheat grains similarly, though their system developed independently.
Greek and Roman Adoption (500 BCE - 500 CE)
Roman grain (granum): Romans used grains of wheat as small weight standards:
- 1 siliqua (carob seed) = 3 grains of wheat
- 24 siliquae = 1 solidus (Roman gold coin, ~4.5 grams)
Classical pharmacy: Greek and Roman physicians (Hippocrates, Galen) prescribed medicines in grain weights, establishing the apothecaries' tradition.
Medieval England (1000-1500 CE)
Barleycorn statutes: English law formalized the barleycorn as both length and weight standard.
King Edward I (1272-1307): His statute defined:
- 1 inch = 3 barleycorns laid end-to-end
- 1 grain = weight of 1 barleycorn from the middle of the ear
Establishing the pound: The avoirdupois pound was defined as 7,000 grains, making the grain the fundamental unit.
Why 7,000? Likely evolved from trade practices. 7,000 is divisible by many numbers (1, 2, 4, 5, 7, 8, 10, 14, 20, etc.), making fractional calculations easier.
Troy vs. Avoirdupois:
- Troy pound: 5,760 grains (12 troy ounces × 480 grains)
- Avoirdupois pound: 7,000 grains (16 avoirdupois ounces × 437.5 grains)
- Grain: Identical in both systems (the common unit)
Gunpowder and Firearms (1300-1800)
Black powder measurement: The invention of gunpowder (China, 9th century; Europe, 13th century) required precise measurement. Early gunners measured powder charges in grains for consistency.
Why grains for gunpowder?
- Precision: Small unit allows fine-tuning of powder charges
- Safety: Overcharging a cannon or musket could cause explosion
- Consistency: Uniform charges improve accuracy
Development of firearms: As firearms evolved from cannons to muskets to rifles (1400s-1800s), grain measurement became standard:
- Musket ball: 400-500 grains (26-32 grams)
- Powder charge: 70-100 grains (4.5-6.5 grams)
Ballistics science: By the 18th century, ballistics became a science, with detailed tables relating bullet weight (grains), powder charge (grains), and muzzle velocity.
Apothecaries' and Pharmacy (1500-1900)
Apothecaries' system: Pharmacists adopted the grain from medieval medicine, using it alongside drams, scruples, and ounces.
System structure:
- 20 grains = 1 scruple
- 3 scruples = 1 dram
- 8 drams = 1 ounce (apothecaries')
- 12 ounces = 1 pound (apothecaries')
Why grains for medicine?
- Precision: Many drugs are potent at milligram doses (grain scale)
- Safety: Overdosing could be fatal; grains allowed careful measurement
- Tradition: Galen, Hippocrates used grains; continuity mattered
Common medications:
- Aspirin: 5 grains (325 mg) — "standard dose"
- Morphine: 1/4 to 1 grain (16-65 mg) — pain relief
- Digitalis: 1/60 to 1/30 grain (1-2 mg) — heart medication
Modern Standardization (1900-Present)
The 1959 Agreement: The international yard and pound agreement fixed the grain:
- 1 pound = 0.45359237 kilograms (EXACT)
- 1 grain = 1/7000 pound = 64.79891 mg (EXACT)
This ended slight variations between British and US grains.
Metrication in pharmacy: Most countries switched to milligrams for drug dosing (1950s-1980s). However:
- United States: Some medications retain grain labels (aspirin, thyroid hormone)
- UK: Fully metric in pharmacy by 1970s
Persistence in ammunition: Unlike pharmacy, the ammunition industry never metricated:
- US ammunition: Grains (dominant globally)
- European ammunition: Some metric (grams), but grains still common for export
Modern shooting sports: Competitive shooting, reloading, and ballistics all use grains:
- Bullet weight: Grains
- Powder charge: Grains
- Arrow weight: Grains (archery)
The pound represents one of the oldest weight measurements in continuous use, with lineage tracing back over two millennia.
Roman Origins: The word "pound" derives from the Latin pondus (weight), while the symbol "lb" comes from libra, the Roman unit of weight equal to approximately 329 grams. The Romans used a libra divided into 12 unciae (ounces), though this differs from the modern 16-ounce pound.
Medieval Development: Multiple "pounds" existed simultaneously in medieval Europe—the tower pound (5,400 grains), merchant's pound (6,750 grains), and troy pound (5,760 grains) for precious metals. This created confusion in commerce and necessitated standardization.
Avoirdupois System: In 13th-century England, the avoirdupois system (from Old French aver de peis, "goods of weight") emerged for general commerce. The avoirdupois pound standardized at 16 ounces, each containing 437.5 grains, totaling 7,000 grains per pound. This system proved so practical for trade that it displaced most other pound definitions.
British Standardization: The Weights and Measures Act of 1824 established the imperial pound throughout the British Empire, legally defining it through physical standards. The Imperial Standard Pound, a platinum cylinder, was kept at the Houses of Parliament as the official definition.
US Independence: After the American Revolution, the United States maintained the British pound definition from colonial times. The Mendenhall Order of 1893 tied US weights to metric standards: 1 pound = 0.4535924277 kilograms (based on 1 meter = 39.37 inches).
1959 International Agreement: The international yard and pound agreement unified English-speaking nations. The United States, United Kingdom, Canada, Australia, New Zealand, and South Africa agreed that 1 pound equals exactly 0.45359237 kilograms. This created perfect mathematical alignment between imperial and metric systems.
Troy vs. Avoirdupois: Two pound systems coexist today. The avoirdupois pound (16 oz, 453.6 g) is used for general commerce and everyday measurements. The troy pound (12 troy oz, 373.2 g) survives only for precious metals—gold, silver, platinum. When someone says "pound" without qualifier, they always mean avoirdupois pound.
Cultural Persistence: Despite metric conversion efforts worldwide, the pound persists in American daily life. The 1975 Metric Conversion Act made metric "preferred" but voluntary, allowing continued pound usage. Today, Americans buy meat in pounds, weigh themselves in pounds, and ship packages in pounds, maintaining a measurement tradition spanning centuries.
Common Uses and Applications: grains vs pounds
Explore the typical applications for both Grain (imperial/US) and Pound (imperial/US) to understand their common contexts.
Common Uses for grains
1. Ammunition Manufacturing and Reloading
The grain is the universal standard for bullet and powder measurement.
Bullet weight: Every ammunition box lists bullet weight in grains:
- 9mm: "115 gr FMJ" = 115-grain full metal jacket
- .308: "168 gr HPBT" = 168-grain hollow-point boat-tail
Powder charges: Reloaders measure powder in grains using precision scales:
- Typical pistol charge: 3-10 grains
- Typical rifle charge: 20-60 grains
Why grains persist:
- Ballistics tables: Decades of data in grains
- Reloading manuals: All recipes in grains
- International standard: Even metric countries use grains for export ammo
- Precision: Grain scale appropriate for small differences that matter
2. Archery
Arrow selection: Archers match arrow weight (grains) to bow draw weight:
- Too light: Bow damage risk
- Too heavy: Poor trajectory
Broadheads: Hunting broadheads sold by weight:
- 75 grain, 100 grain, 125 grain, etc.
Tuning: Archers adjust arrow weight by changing point weight (grains) to fine-tune flight.
3. Pharmaceuticals (Historical and Residual)
United States: Some medications still list grain dosages:
- Aspirin: 5 grain (325 mg)
- Thyroid medication: Grain equivalents
Medical history: Understanding grain dosages important for:
- Historical medical research
- Old prescriptions
- Classic pharmaceutical formulations
4. Jewelry and Precious Metals
Troy system: Grains underpin the troy weight system used for gold, silver, platinum.
Jeweler's usage:
- Weighing scrap: Pennyweights (24 grains)
- Gold purity calculations: Grain-based math
- Stone setting: Small gemstones sometimes measured in grains
5. Historical and Collectors' Context
Numismatics (coin collecting): Historical coins' weights recorded in grains:
- Helps identify counterfeits (wrong weight)
- Documents wear (lost grains over time)
Antique firearms: Black powder firearms measured in grains:
- "This musket took 90 grains of powder and a 450-grain ball"
6. Scientific and Educational
Teaching weight systems: The grain demonstrates the connection between avoirdupois, troy, and apothecaries' systems.
Historical science: Understanding old experiments and recipes requires grain knowledge:
- 18th-century chemistry
- Medieval alchemy
- Renaissance medicine
7. International Trade
Ammunition export: US and European manufacturers use grains globally:
- 124 gr 9mm NATO standard (worldwide)
- Even metric-preferring countries import grain-labeled ammo
When to Use pounds
Medical and Healthcare Settings
Healthcare in the US primarily operates in pounds for patient weight, though hospitals increasingly record kilograms for medication dosing calculations. Patient charts typically show both: "185 lbs (84 kg)." However, all patient communication uses pounds—doctors say "You've gained 5 pounds" or "Try to lose 10-15 pounds," never kilograms.
Weight-based medication dosing creates complexity: drugs dose in mg/kg, requiring conversion. A 160-lb patient equals 72.6 kg, so a drug dosed at 5 mg/kg requires 363 mg. Medical staff use conversion charts or electronic calculators to prevent errors.
Anesthesiology requires precise weight for medication dosing. Operating room scales display both pounds and kilograms, with staff typically asking patients "What's your weight in pounds?" for verification against chart data.
Public health BMI calculations use pounds and inches in the US: BMI = (weight in pounds × 703) ÷ (height in inches)². A person 5'9" (69") weighing 170 lbs has BMI = (170 × 703) ÷ (69 × 69) = 25.1, just into the "overweight" category (BMI 25-29.9).
Weight Loss and Fitness Industry
Diet programs, weight loss apps, and fitness tracking exclusively use pounds in the US market. Weight Watchers, MyFitnessPal, Lose It!, and similar apps default to pounds, though users can switch to kilograms.
Fitness goals frame in pounds: "Lose 20 pounds by summer," "Gain 10 pounds of muscle," "Drop 5 pounds this month." Personal trainers track client progress in pounds, celebrating milestone losses: "You've lost 25 pounds—that's like losing two bowling balls!"
Scale psychology creates significance for specific numbers. Dropping below 200 lbs (reaching "onederland") represents a major milestone for many dieters. Breaking into the 100s (199 lbs) feels dramatically different from 200 lbs despite being only 1 pound difference.
Bodybuilding competitions divide by weight classes in pounds: lightweight (<154 lbs), middleweight (154-176 lbs), light-heavyweight (176-198 lbs), heavyweight (198-242 lbs), super-heavyweight (>242 lbs). Competitors cut weight aggressively, sometimes losing 10-20 lbs of water weight in final days before weigh-in.
Commercial Food Service and Restaurants
Restaurant kitchens order ingredients in pounds and bulk quantities:
- 50-lb bags of onions
- 40-lb cases of chicken breast
- 25-lb blocks of cheese
- 5-lb containers of mayonnaise
- 10-lb boxes of bacon
Recipe scaling in commercial kitchens calculates in pounds: a recipe serving 20 using 2 lbs ground beef scales to serve 100 by using 10 lbs. Kitchen scales measure in pounds and ounces, with precision to 0.1 oz for small quantities.
Food costs calculate per pound: if chicken costs $2.50/lb and a dish uses 6 oz (0.375 lbs), the protein cost is $0.94 per serving. Restaurant profitability depends on accurate food costing, requiring staff to think fluently in pounds and ounces.
Portion control uses ounces: 8-oz steak, 6-oz salmon fillet, 4-oz burger patty (quarter-pounder). Pre-portioned proteins simplify cooking and ensure consistency. A case of forty 4-oz burger patties weighs 10 lbs total.
Postal and Freight Shipping
The entire US shipping industry operates in pounds. Postage rates tier by weight:
USPS First-Class Mail:
- Up to 3 oz: $0.63 (letter)
- Up to 13 oz: Incrementally increases
- Over 13 oz: Requires Priority Mail
Priority Mail tiers:
- Up to 1 lb: $8.50 flat rate (approximate regional)
- 1-2 lbs: $9.50
- 2-3 lbs: $11.00
- Continues in 1-lb increments to 70 lbs
Shipping costs increase dramatically with weight. A 15.5-lb package costs significantly more than a 15-lb package if it crosses a tier boundary. Online sellers optimize packaging to stay within weight tiers: use lighter boxes, remove unnecessary materials, choose compact packaging.
Freight shipping (over 150 lbs) charges by "hundredweight" (CWT): cost per 100 lbs. A 750-lb shipment traveling 500 miles at $45/CWT costs $337.50 (7.5 × $45).
Farming and Agriculture
Agricultural commerce operates entirely in pounds:
Crop yields per acre:
- Corn: 170-200 bushels/acre (56 lbs per bushel = 9,520-11,200 lbs/acre)
- Soybeans: 50-60 bushels/acre (60 lbs per bushel = 3,000-3,600 lbs/acre)
- Wheat: 50-70 bushels/acre (60 lbs per bushel = 3,000-4,200 lbs/acre)
Livestock weights:
- Market hogs: Sold at 250-280 lbs live weight
- Feeder cattle: Sold at 600-800 lbs, finished at 1,200-1,400 lbs
- Broiler chickens: Processed at 5-6 lbs
- Turkeys: Processed at 25-30 lbs
Feed calculations:
- Dairy cow eats 50-60 lbs of feed daily
- Beef cattle eat 25-30 lbs of feed daily during finishing
- Horse eats 15-25 lbs of hay daily
- Bag of horse feed: 50 lbs (common size)
Farmers sell crops and livestock by the pound or hundredweight (100 lbs). Commodity prices quote in cents per pound: corn at $0.055/lb, soybeans at $0.15/lb (converted from bushel prices).
Manufacturing and Industrial Production
Manufacturing specs, especially for non-precision work, use pounds:
Sheet metal weight:
- Steel sheet weight: pounds per square foot for given thickness
- Aluminum sheet: Lighter than steel at same thickness
- Copper sheet: Heavier than steel
Material handling:
- Pallet weight limits: 2,500 lbs typical
- Forklift capacity: 3,000-5,000 lbs common
- Hand truck/dolly: 500-800 lbs capacity
Product specifications:
- Appliances: Refrigerator 200-300 lbs, washing machine 150-200 lbs
- Furniture: Dining table 50-150 lbs, dresser 100-200 lbs
- Machinery: Small lathe 500-1,500 lbs, mill 2,000-5,000 lbs
Shipping and logistics calculate by weight and dimensions. Freight classifications assign classes based on weight density (pounds per cubic foot): class 50 (50+ lbs/cu ft, densest), class 500 (1 lb/cu ft, lightest).
Waste Management and Recycling
Waste services charge based on weight:
Dumpster weight limits:
- 10-yard dumpster: 2-3 tons (4,000-6,000 lbs) weight limit
- 20-yard dumpster: 3-4 tons (6,000-8,000 lbs)
- 40-yard dumpster: 5-6 tons (10,000-12,000 lbs)
Exceeding weight limits incurs fees: $50-100 per ton over limit. Construction debris (concrete, brick, dirt) quickly exceeds weight limits despite not filling volume.
Recycling programs:
- Aluminum cans: ~30 cans per pound, recyclers pay $0.30-0.50/lb
- Scrap steel: $0.05-0.15/lb
- Copper: $2-4/lb (valuable, often stolen)
- Cardboard: $0.02-0.10/lb
- Paper: $0.01-0.05/lb
Individuals recycling metals weigh loads at scrap yards on drive-over scales, receiving payment based on total pounds by category.
Pet Care and Veterinary Medicine
Pet food portion recommendations use pounds:
- Small dogs (<20 lbs): 1/2 to 1 cup food daily
- Medium dogs (20-50 lbs): 1 to 2 cups daily
- Large dogs (50-90 lbs): 2 to 3.5 cups daily
- Giant dogs (>90 lbs): 3.5 to 5+ cups daily
Medication dosing requires accurate pet weight. A 40-lb dog receiving medication at 1 mg/lb needs a 40 mg dose. Underdosing proves ineffective; overdosing risks toxicity.
Veterinarians track pet weight over time, flagging unhealthy gains or losses. "Fluffy has gained 3 pounds since last year—we need to reduce portions" or "Max has lost 5 pounds unexpectedly—let's run some tests."
Additional Unit Information
About Grain (gr)
1. How many grains are in an ounce (avoirdupois)?
Exactly 437.5 grains.
This is a defined relationship in the avoirdupois system:
- 1 pound (avoirdupois) = 7,000 grains
- 1 pound = 16 ounces
- 1 ounce = 7,000 ÷ 16 = 437.5 grains
2. How many grains are in a pound (avoirdupois)?
Exactly 7,000 grains.
The avoirdupois pound is defined as 7,000 grains. This is the legal definition in both US and UK systems (since the 1959 international agreement).
Example: A 1-pound bag of bullets contains 7,000 grains of lead.
3. How many milligrams are in a grain?
Exactly 64.79891 milligrams.
This precise value comes from:
- 1 pound = 453.59237 grams (defined, 1959)
- 1 grain = 1/7000 pound
- 1 grain = 453.59237 ÷ 7000 = 0.06479891 g = 64.79891 mg
4. Why is ammunition measured in grains instead of grams?
Historical precedent and global standardization.
Reasons:
- Ballistics data: Centuries of data in grains (velocity, energy, trajectory)
- Reloading manuals: All powder recipes in grains
- International standard: Even metric countries export ammo labeled in grains
- Precision: Grain scale (65 mg) well-suited for bullet weights (2-50 grams)
- Continuity: Changing would require recalibrating every firearm manual and table
Result: The shooting industry worldwide uses grains, regardless of country.
5. Is a grain the same in troy, avoirdupois, and apothecaries' systems?
Yes, exactly the same.
The grain is the only unit shared identically across all three systems:
- 1 grain (avoirdupois) = 64.79891 mg
- 1 grain (troy) = 64.79891 mg
- 1 grain (apothecaries') = 64.79891 mg
Why this matters: The grain is the common denominator, allowing conversion between systems.
Example:
- 480 grains = 1 troy ounce = 1 apothecaries' ounce
- 437.5 grains = 1 avoirdupois ounce (different!)
6. How many grains are in a gram?
Approximately 15.43236 grains.
Formula:
1 gram = 1,000 mg
1 grain = 64.79891 mg
1 gram = 1,000 ÷ 64.79891 = 15.43236 grains
Quick approximation: 1 gram ≈ 15.4 grains (useful for mental math)
7. What does "5 grain aspirin" mean?
A tablet containing 5 grains of aspirin = 325 milligrams.
Calculation:
5 grains × 64.79891 mg/grain = 323.99 mg ≈ 325 mg
Why 325 mg tablets? Historical: Aspirin was formulated in grain dosages. When pharmacy metricated, 5 grains became 325 mg (rounded for convenience).
8. How much does a barleycorn actually weigh?
About 50-70 milligrams, depending on variety.
Modern grain vs. actual barleycorn:
- Defined grain: 64.79891 mg (EXACT)
- Actual barleycorn: 50-70 mg (varies)
Remarkably close! Medieval barleycorns averaged ~65 mg, very close to the modern definition.
Why the difference today? The grain is now a defined constant, not dependent on actual barley. This ensures global consistency.
9. Why is the grain 1/7000 of a pound?
Historical evolution, not mathematical planning.
Theory: The pound and grain evolved separately:
- Grain: Ancient seed weight
- Pound: Medieval trade weight
The 7,000-grain pound emerged from trade practices and was standardized by law (13th-14th century England).
Convenience: 7,000 is highly divisible (1, 2, 4, 5, 7, 8, 10, 14, 20, 25, 28, 35, 40, 50, 56, 70, 100, 125, 140, 175, 200, 250, 280, 350, 500, 700, 1000, 1400, 1750, 2333, 3500, 7000), making fractional calculations easier in pre-calculator commerce.
10. Do other countries use grains?
Yes, for ammunition and archery worldwide.
By country:
- United States: Grains for ammo, archery, some pharmaceuticals
- United Kingdom: Grains for ammo, archery (pharmacy now metric)
- Europe: Grains for ammunition exports, some domestic ammo
- Asia, Australia: Grains for ammunition, archery
Pharmaceutical use: Mostly obsolete outside the U.S. (switched to milligrams).
Why grains persist globally: Ammunition is an international market. Standardization on grains ensures compatibility.
11. How accurate do reloading scales need to be?
±0.1 grain (±0.0065 grams) minimum.
Why such precision?
- Small powder charges: 3-10 grains (pistol), 20-60 grains (rifle)
- ±0.1 grain = ±1-3% variation (acceptable)
- ±1 grain = ±10-30% variation (dangerous!)
Scale types:
- Beam balance: Manual, ±0.1 grain typical
- Digital: Electronic, ±0.1 grain or better
- Trickler: Adds powder grain-by-grain for exactness
Safety: Reloading is unforgiving. Precision scales are essential to avoid overpressure, case ruptures, or injuries.
12. What is the relationship between grain and carat?
1 carat (gemstone) = 200 milligrams = 3.086 grains.
Calculation:
1 carat = 200 mg
1 grain = 64.79891 mg
1 carat = 200 ÷ 64.79891 = 3.086 grains
Historical connection: Both derive from seeds:
- Grain: Barleycorn
- Carat: Carob seed (~200 mg)
Modern difference:
- Carat: Used for gemstones (diamonds, rubies, sapphires)
- Grain: Used for bullets, arrows, pharmaceuticals
Overlap: Small gemstones or pearls historically measured in grains; now almost exclusively carats.
About Pound (lb)
How many ounces are in a pound?
There are exactly 16 ounces in 1 avoirdupois pound. This relationship is fundamental to the US customary weight system and has remained constant since the avoirdupois system was standardized in 13th-century England.
The 16-ounce division allows convenient fractional measurements: 1/2 pound = 8 oz, 1/4 pound = 4 oz (quarter-pounder burger), 1/8 pound = 2 oz. Food packaging commonly uses both: "1 lb (16 oz)" or "12 oz (3/4 lb)."
Converting pounds to ounces: Multiply pounds by 16
- 1 lb = 16 oz
- 2.5 lbs = 40 oz
- 0.75 lbs = 12 oz (three-quarters of a pound)
Converting ounces to pounds: Divide ounces by 16
- 32 oz = 2 lbs
- 24 oz = 1.5 lbs
- 10 oz = 0.625 lbs
Mixed notation: "5 lbs 10 oz" means 5 pounds + 10 ounces = (5 × 16) + 10 = 90 ounces total.
Important distinction: Fluid ounces (volume) and ounces (weight) are different measurements. "16 fluid ounces" of water weighs approximately 16 ounces, but 16 fluid ounces of honey weighs about 24 ounces. The context determines which "ounce" is meant.
How do I convert pounds to kilograms?
To convert pounds to kilograms, multiply by 0.45359237. This is the exact conversion factor established by the 1959 international agreement.
Formula: kilograms = pounds × 0.45359237
Examples:
- 1 lb = 0.454 kg
- 10 lbs = 4.536 kg
- 50 lbs = 22.680 kg
- 100 lbs = 45.359 kg
- 150 lbs = 68.039 kg
- 200 lbs = 90.718 kg
Quick approximation: For mental math, divide pounds by 2.2 (or multiply by 0.45):
- 100 lbs ÷ 2.2 ≈ 45.5 kg (actual: 45.36 kg)
- 150 lbs ÷ 2.2 ≈ 68.2 kg (actual: 68.04 kg)
Reverse conversion (kg to lbs): Multiply kilograms by 2.20462
- 10 kg = 22.046 lbs
- 50 kg = 110.231 lbs
- 75 kg = 165.347 lbs
For professional contexts (medical dosing, commercial trade, engineering), always use the exact conversion factor. For casual estimates ("How heavy is that in kilograms?"), dividing by 2.2 provides close enough results.
What measurement system uses pounds?
The pound (lb) is a key unit in the imperial and US customary measurement systems. While the UK officially adopted the metric system in 1965, pounds remain common for body weight, and road signs still show distances in miles. The United States uses pounds extensively across all aspects of daily life.
Where pounds are standard:
- United States: Primary weight unit for commerce, body weight, cooking, shipping
- United Kingdom: Still common for body weight (though officially metric)
- Canada: Used alongside metric, especially for body weight and produce
- Caribbean nations: Many former British colonies maintain some imperial usage
Where kilograms dominate:
- European Union countries (mandatory metric since 1960s-1990s)
- Asia (Japan, China, Korea, etc.)
- Australia and New Zealand (converted to metric 1970s)
- Latin America
- Africa (except Liberia)
Hybrid usage: Many countries officially metric still use pounds informally. UK residents often describe body weight in stones and pounds despite official metric policy. Canada labels food in both grams and ounces.
Where is the pound commonly used?
The pound is primarily used in the United States for everyday measurements. Americans use pounds for:
Personal:
- Body weight (bathroom scales, medical records)
- Baby weight ("7 pounds, 6 ounces")
- Pet weight (vet visits, food portions)
- Luggage weight (airline limits)
Commerce:
- Grocery pricing ($3.99/lb for meat, produce)
- Postal shipping (USPS rates by pound)
- Food packaging (5-lb bag of flour)
- Restaurant portions (8-oz steak, quarter-pound burger)
Industrial:
- Construction materials (80-lb bag of concrete)
- Agricultural commodities (livestock sold per pound)
- Manufacturing specifications (product weights)
- Freight shipping (charges per 100 lbs)
The United Kingdom and Canada also use pounds commonly, though officially metric. UK residents often state body weight in stones and pounds. Canadian grocery stores show prices in both $/lb and $/kg.
In aviation, pounds of thrust measure jet engine power worldwide, and pounds of fuel calculate aircraft loading, even in metric countries—similar to altitude measured in feet globally.
Why do we use "lb" for pound?
The symbol "lb" comes from the Latin word libra, meaning balance or scales, which was the Roman unit of weight. The word "pound" itself derives from Latin pondus (weight), while the abbreviation preserved the Roman unit name.
Historical explanation:
- Roman libra ≈ 329 grams (about 0.7 modern pounds)
- Medieval scholars used "lb" as the standard abbreviation
- When the avoirdupois pound (16 oz, 454g) became England's commercial standard, it retained the Roman abbreviation despite the different weight value
Modern usage:
- "lb" serves both singular and plural (1 lb, 5 lb, not "5 lbs" technically, though "lbs" is common)
- Pronounced "pound" or "pounds" despite the letters "l-b"
- Used internationally in trade: "100 lb net weight"
Related terms:
- PSI = Pounds per Square Inch (pressure)
- lb-ft = pound-feet (torque)
- lb-test = fishing line strength (pounds of force before breaking)
The disconnect between spelling (lb) and pronunciation (pound) confuses English learners, but it's deeply embedded in language. No serious proposals exist to change it—tradition preserves the Roman abbreviation despite its non-phonetic representation.
What's the difference between mass and weight in pounds?
In scientific terms, mass measures the amount of matter in an object (kilogram or pound-mass), while weight measures the gravitational force on that mass (Newton or pound-force). However, in everyday American usage, "pound" refers to both interchangeably without distinction.
Scientific definitions:
- Mass (lbm): Amount of matter, constant regardless of location
- Weight (lbf): Force due to gravity = mass × acceleration
On Earth's surface, an object with 1 pound-mass (lbm) experiences 1 pound-force (lbf) of weight. On the Moon (1/6 Earth's gravity), that 1 lbm object would weigh only 0.167 lbf—but bathroom scales there would still show "1 lb" because they're calibrated for Earth gravity.
Everyday reality: When Americans say "I weigh 150 pounds," they technically mean "I have a mass that creates 150 pounds-force on Earth." Scales measure force (weight) but display mass units (pounds) assuming Earth gravity.
Engineering context: Engineers distinguish lbm (pound-mass) from lbf (pound-force) in calculations involving acceleration, thrust, or different gravitational environments. Aerospace applications carefully track both since spacecraft experience varying gravitational forces.
Practical impact: For everyday purposes—buying meat, weighing luggage, measuring body weight—the distinction doesn't matter. All occur at Earth's surface where 1 lbm = 1 lbf. Only in scientific, aerospace, or physics contexts does the mass vs. weight distinction require precision.
How much is a stone in pounds?
One stone equals exactly 14 pounds. The stone is a British imperial unit of weight still commonly used in the UK and Ireland for human body weight, though officially replaced by kilograms in most contexts.
Common conversions:
- 1 stone = 14 lbs = 6.35 kg
- 10 stone = 140 lbs = 63.5 kg
- 12 stone = 168 lbs = 76.2 kg
- 15 stone = 210 lbs = 95.3 kg
UK usage: British people typically express body weight in stones and pounds together:
- "I weigh 11 stone 8" = 11 stone + 8 lbs = 154 + 8 = 162 lbs total
- "I've lost half a stone" = lost 7 lbs
- "I need to lose 2 stone" = need to lose 28 lbs
Historical context: The stone was standardized in 1835 at 14 pounds for weighing people. Different stone weights existed historically for various commodities: wool stone (14 lbs), meat stone (8 lbs), cheese stone (16 lbs). The 14-pound definition survived for body weight.
Modern decline: Official UK government documents and medical records now use kilograms following metrication. However, bathroom scales in UK homes often still display stones and pounds, and older generations particularly think in stones when discussing weight.
US usage: Americans rarely use stones. When British media mentions someone weighing "12 stone," American audiences need conversion to understand this means 168 lbs.
Can you mix pounds and ounces in calculations?
Yes, but you must handle them carefully to avoid errors. Pounds and ounces can be added, subtracted, multiplied, and divided, but excess ounces must convert to pounds (since 16 oz = 1 lb).
Addition/Subtraction: Add or subtract pounds and ounces separately, then convert excess ounces:
- 5 lbs 10 oz + 3 lbs 8 oz = 8 lbs 18 oz = 9 lbs 2 oz (convert 18 oz = 1 lb 2 oz)
- 7 lbs 4 oz − 2 lbs 10 oz: borrow 1 lb = 16 oz, so 7 lbs 4 oz = 6 lbs 20 oz, then 6 lbs 20 oz − 2 lbs 10 oz = 4 lbs 10 oz
Multiplication/Division: Convert entirely to ounces or decimal pounds:
- Double 3 lbs 6 oz: Convert to 54 oz, double = 108 oz = 6 lbs 12 oz
- Half of 5 lbs 10 oz: Convert to 90 oz, half = 45 oz = 2 lbs 13 oz
- Or use decimal: 5 lbs 10 oz = 5.625 lbs, half = 2.8125 lbs = 2 lbs 13 oz
Decimal conversion:
- Pounds to decimal: 5 lbs 10 oz = 5 + (10÷16) = 5.625 lbs
- Decimal to pounds-ounces: 3.75 lbs = 3 lbs + 0.75 lbs = 3 lbs + 12 oz = 3 lbs 12 oz
Kitchen scales: Many digital scales switch between decimal pounds (5.63 lbs) and pounds-ounces (5 lbs 10 oz). Use decimal for recipe scaling and math, pounds-ounces for traditional recipes and portions.
What's a "hundredweight" and how does it relate to pounds?
A hundredweight (abbreviated cwt) is a unit equal to 100 pounds in the US customary system. It's primarily used in freight shipping, agriculture, and commodity trading for pricing and calculating large quantities.
US hundredweight (short hundredweight): 100 pounds exactly
- Used in United States and Canada
- Freight rates often quote as $/cwt (dollars per hundred pounds)
- Commodity prices: livestock, grains sometimes price per cwt
UK hundredweight (long hundredweight): 112 pounds (8 stone)
- Used historically in British imperial system
- Now largely obsolete in favor of metric
- Equal to 1/20 of a UK long ton (2,240 lbs)
Practical examples:
- Freight charges: "$25/cwt" means $25 per 100 lbs
- A 500-lb shipment at $25/cwt costs 5 × $25 = $125
- Cattle pricing: "$180/cwt" means $1.80/lb; 1,200-lb steer = $2,160
Ton relationships:
- US short ton = 2,000 lbs = 20 cwt
- UK long ton = 2,240 lbs = 20 (UK) cwt
- Metric tonne = 2,204.6 lbs ≈ 22 cwt
Why it persists: Hundredweight provides convenient round numbers for commodity trading and freight pricing. Saying "$45 per hundredweight" sounds simpler than "$0.45 per pound," and multiplying weight by hundredweight rate requires fewer decimal places.
How accurate do bathroom scales measure pounds?
Typical consumer bathroom scales measure weight accurate to ±0.2-1 pound (±90-450 grams), depending on quality and calibration. This means a scale showing "150 lbs" indicates your actual weight is likely between 149-151 lbs.
Scale types and accuracy:
- Spring/mechanical scales: ±1 lb typical accuracy, can drift over time
- Basic digital scales: ±0.5 lb typical accuracy
- High-quality digital scales: ±0.2 lb accuracy (±90 grams)
- Medical-grade scales: ±0.1 lb accuracy (±50 grams)
- Laboratory balances: ±0.01 lb accuracy (±5 grams)
Factors affecting accuracy:
- Surface: Scales must sit on hard, flat, level floors; carpet adds error
- Calibration: Scales drift over time and need periodic calibration
- Battery: Low battery affects digital scale accuracy
- Temperature: Extreme temperatures alter spring tension or sensor readings
- Weight distribution: Leaning or shifting weight creates false readings
Consistency vs. accuracy: For weight tracking, consistency matters more than absolute accuracy. If your scale consistently reads 2 lbs heavy, you can still track changes accurately. Weigh yourself same time daily (morning after bathroom, before eating), same scale, same conditions.
Verification: To check scale accuracy, weigh a known weight (10-lb dumbbell, 5-lb bag of flour). If the scale shows 10.2 lbs for a 10-lb dumbbell, it's within reasonable tolerance. Differences over 0.5 lbs suggest recalibration needed.
Conversion Table: Grain to Pound
| Grain (gr) | Pound (lb) |
|---|---|
| 0.5 | 0 |
| 1 | 0 |
| 1.5 | 0 |
| 2 | 0 |
| 5 | 0.001 |
| 10 | 0.001 |
| 25 | 0.004 |
| 50 | 0.007 |
| 100 | 0.014 |
| 250 | 0.036 |
| 500 | 0.071 |
| 1,000 | 0.143 |
People Also Ask
How do I convert Grain to Pound?
To convert Grain to Pound, enter the value in Grain 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 Grain to Pound?
The conversion factor depends on the specific relationship between Grain and Pound. 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 Pound back to Grain?
Yes! You can easily convert Pound back to Grain by using the swap button (⇌) in the calculator above, or by visiting our Pound to Grain converter page. You can also explore other weight conversions on our category page.
Learn more →What are common uses for Grain and Pound?
Grain and Pound 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:
- Kilogram (kg) • Grain to Kilogram
- Gram (g) • Grain to Gram
- Milligram (mg) • Grain to Milligram
- Ounce (oz) • Grain to Ounce
- Stone (st) • Grain to Stone
- Ton (metric) (t) • Grain to Ton (metric)
- Ton (US) (ton) • Grain to Ton (US)
- Ton (UK) (long ton) • Grain to Ton (UK)
- Microgram (µg) • Grain to Microgram
- Carat (ct) • Grain 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