Conversion method
Choose the definition that matches your measurement, then round the result to a useful precision.
lb = x × 2.2046226218487757
10 kg = 22.046226 lb.
| kg | lb |
|---|---|
| 1 | 2.204623 |
| 5 | 11.023113 |
| 10 | 22.046226 |
| 25 | 55.115566 |
| 50 | 110.231131 |
| 100 | 220.462262 |
Mass versus weight
Strictly, mass is the amount of matter in an object and weight is the force gravity exerts on that mass. Mass is measured in kilograms; weight, being a force, is properly measured in newtons. In everyday use the two are treated as interchangeable because gravity is effectively constant across the Earth's surface.
The distinction becomes real away from Earth. An object with a mass of 70 kg has that same mass on the Moon but weighs about one sixth as much, because lunar gravity is weaker. Bathroom scales measure force and report an implied mass, which is why they would read differently on the Moon despite the body being unchanged.
Key conversion factors
As with length, the metric-imperial link is exact by definition: the international pound is defined as exactly 0.45359237 kilograms.
- 1 kilogram = 2.20462 pounds
- 1 pound = 0.45359237 kg exactly = 16 ounces
- 1 ounce = 28.3495 grams
- 1 stone = 14 pounds = 6.35029 kg
- 1 US ton (short ton) = 2,000 lb = 907.185 kg
- 1 metric ton (tonne) = 1,000 kg = 2,204.62 lb
| kg | lb | st and lb |
|---|---|---|
| 50 | 110.2 | 7 st 12.2 lb |
| 55 | 121.3 | 8 st 9.3 lb |
| 60 | 132.3 | 9 st 6.3 lb |
| 65 | 143.3 | 10 st 3.3 lb |
| 70 | 154.3 | 11 st 0.3 lb |
| 75 | 165.3 | 11 st 11.3 lb |
| 80 | 176.4 | 12 st 8.4 lb |
| 85 | 187.4 | 13 st 5.4 lb |
| 90 | 198.4 | 14 st 2.4 lb |
| 95 | 209.4 | 14 st 13.4 lb |
| 100 | 220.5 | 15 st 10.5 lb |
| 110 | 242.5 | 17 st 4.5 lb |
| 120 | 264.6 | 18 st 12.6 lb |
Stone, and the three kinds of ton
The stone, equal to 14 pounds, remains in common use for body weight in the UK and Ireland, where someone might describe themselves as 11 stone 4 rather than 158 pounds. It is essentially unused in the United States.
Ton is genuinely ambiguous and worth clarifying in any context where it matters. The US short ton is 2,000 pounds, the UK long ton is 2,240 pounds, and the metric tonne is 1,000 kilograms, or about 2,205 pounds. The long ton and the tonne differ by only about 1.6%, which makes the ambiguity easy to overlook and occasionally expensive.
| Ton | Pounds | Kilograms | Where used |
|---|---|---|---|
| US short ton | 2,000 lb | 907.185 kg | United States |
| UK long ton | 2,240 lb | 1,016.05 kg | United Kingdom, shipping |
| Metric tonne | 2,204.62 lb | 1,000 kg | Everywhere metric; often written t |
Troy weight for precious metals
Gold, silver, and platinum are traded in troy ounces, which are heavier than the ordinary avoirdupois ounces used for food and shipping. A troy ounce is about 31.103 grams against 28.350 grams for a standard ounce — roughly 10% more.
The troy pound compounds the confusion by containing 12 troy ounces rather than 16, making it lighter than a standard pound overall. When a price is quoted per ounce for a precious metal, it is virtually always a troy ounce, and this converter uses standard avoirdupois units throughout.
| Unit | Grams | Subdivision | Used for |
|---|---|---|---|
| Avoirdupois ounce | 28.3495 g | 16 to the pound | Food, shipping, body weight |
| Troy ounce | 31.1035 g | 12 to the troy pound | Gold, silver, platinum prices |
| Avoirdupois pound | 453.592 g | 16 oz | Everyday weight |
| Troy pound | 373.242 g | 12 oz t | Rarely used; lighter than the everyday pound |
Ounces to grams for the kitchen
Recipe conversions are the other everyday case. An ounce is 28.35 grams, so a rough rule of 30 g per ounce overstates by about 6% — fine for most cooking, not for baking.
| oz | g | lb |
|---|---|---|
| 1 | 28.3 | 0.0625 |
| 2 | 56.7 | 0.125 |
| 3 | 85 | 0.1875 |
| 4 | 113.4 | 0.25 |
| 6 | 170.1 | 0.375 |
| 8 | 226.8 | 0.5 |
| 12 | 340.2 | 0.75 |
| 16 | 453.6 | 1 |
Unit definitions and sources
These units measure mass, not force. Metric tonnes, US short tons, UK long tons and troy ounces have distinct definitions.
23 of the 35 definitions below were checked against the cited sources on 2026-09-20 (AI-assisted check).
| Unit and system | Use | Definition | Relationship |
|---|---|---|---|
| Milligram (mg); si | Common units | Milligram measures mass. kg = (value in mg) × 0.000001. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Gram (g); si | Common units | Gram measures mass. kg = (value in g) × 0.001. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Kilogram (kg); si | Common units | Kilogram measures mass. kg = (value in kg) × 1. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Metric ton (t); si | Common units | Metric ton measures mass. kg = (value in t) × 1000. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Ounce (oz); us | Common units | Ounce measures mass. kg = (value in oz) × 0.028349523125. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Pound (lb); us | Common units | Pound measures mass. kg = (value in lb) × 0.45359237. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Stone (st); imperial | Common units | Stone measures mass. kg = (value in st) × 6.35029318. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| US ton (short) (ton); us | Common units | US ton (short) measures mass. kg = (value in ton) × 907.18474. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| UK ton (long) (long ton); imperial | Common units | UK ton (long) measures mass. kg = (value in long ton) × 1016.0469088000001. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Troy ounce (oz t); other | Specialist units | Troy ounce measures mass. kg = (value in oz t) × 0.0311034768. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Carat (ct); other | Specialist units | Carat measures mass. kg = (value in ct) × 0.0002. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Atomic mass unit (u); other | Specialist units | Atomic mass unit measures mass. kg = (value in u) × 1.66053906892e-27. Common use: Package and material mass. | Approximate / conventional |
| Grain (gr); other | Specialist units | A grain is exactly 0.00006479891 kilograms, or 1/7000 of an avoirdupois pound. Common use: Small traditional mass measurements. The symbol gr means grain; g means gram. | Exact definition; numerical display may be rounded |
| Pennyweight (dwt); other | Specialist units | Pennyweight: multiply by 0.00155517384 to obtain the category base unit. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Troy pound (lb t); other | Specialist units | Troy pound: multiply by 0.3732417216 to obtain the category base unit. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Hundredweight (US short) (US cwt); other | Specialist units | Hundredweight (US short): multiply by 45.359237 to obtain the category base unit. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Hundredweight (UK long) (UK cwt); other | Specialist units | Hundredweight (UK long): multiply by 50.80234544 to obtain the category base unit. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Slug (slug); other | Specialist units | Slug: multiply by 14.593902937206362 to obtain the category base unit. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Dram (avoirdupois) (dr); other | Specialist units | Dram (avoirdupois): multiply by 0.0017718451953125 to obtain the category base unit. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Exagram (Eg); si | Specialist units | exagram: E denotes 10^18; the unit gives 1000000000000000 kg. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Petagram (Pg); si | Specialist units | petagram: P denotes 10^15; the unit gives 1000000000000 kg. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Teragram (Tg); si | Specialist units | teragram: T denotes 10^12; the unit gives 1000000000 kg. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Gigagram (Gg); si | Specialist units | gigagram: G denotes 10^9; the unit gives 1000000 kg. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Megagram (Mg); si | Specialist units | megagram: M denotes 10^6; the unit gives 1000 kg. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Hectogram (hg); si | Specialist units | hectogram: h denotes 10^2; the unit gives 0.1 kg. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Decagram (dag); si | Specialist units | decagram: da denotes 10^1; the unit gives 0.01 kg. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Decigram (dg); si | Specialist units | decigram: d denotes 10^-1; the unit gives 0.0001 kg. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Centigram (cg); si | Specialist units | centigram: c denotes 10^-2; the unit gives 0.00001 kg. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Microgram (µg); si | Specialist units | microgram: µ denotes 10^-6; the unit gives 1e-9 kg. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Nanogram (ng); si | Specialist units | nanogram: n denotes 10^-9; the unit gives 1e-12 kg. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Picogram (pg); si | Specialist units | picogram: p denotes 10^-12; the unit gives 1e-15 kg. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Femtogram (fg); si | Specialist units | femtogram: f denotes 10^-15; the unit gives 1e-18 kg. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Attogram (ag); si | Specialist units | attogram: a denotes 10^-18; the unit gives 1e-21 kg. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Kilogram-force square second/meter (kgf·s²/(m)); other | Specialist units | kilogram-force square second/meter = 9.80665 kg, derived from the component SI/customary definitions. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
| Pound-force square second/foot (lbf·s²/(ft)); other | Specialist units | pound-force square second/foot = 14.593902937206362 kg, derived from the component SI/customary definitions. Common use: Package and material mass. | Exact definition; numerical display may be rounded |
Sources: BIPM: International System of Units; NIST: SP 811 Appendix B.8: conversion factors; NIST: 2022 CODATA recommended constants; BIPM: SI prefixes
Precision of weight and mass conversions
All 35 weight and mass units convert through Kilogram (kg). 34 have an exact defined relationship to the base unit and 1 is conventional or measured values. Results and the tables on this page come from the same engine, so a table value can be checked against the converter directly.
Standard display shows up to six decimal places, switching to scientific notation for very large or small values. Calculation uses JavaScript binary floating point independently of display rounding, so extra digits are not a claim about measurement accuracy. Each unit lists its own source; a citation records where the definition comes from, not an independent review. See Conversion methodology for the review and correction process.