Convert any weight to every common unit at once: grams and kilograms, ounces, pounds and stones, US and UK tons, troy ounces for precious metals, carats and grains.
1 lb = 0.45359237 kg exactly
Since 2019, the kilogram has been defined by fixing the value of the Planck constant, replacing the platinum-iridium cylinder kept near Paris that served as the standard for 130 years. The pound has no separate standard of its own: since the 1959 international yard and pound agreement, it has been defined as exactly 0.45359237 kg. Every pound, ounce, stone and ton conversion on this page is therefore exact.
Strictly, all of these are units of mass. Weight is the force of gravity on a mass, but in everyday use, and on scales, the two words mean the same thing.
"Ounce" can mean three different things. The everyday ounce is used for food and post, the troy ounce for precious metals, and the fluid ounce measures volume, not weight. A troy ounce is about 10% heavier than an everyday ounce, but a troy pound is lighter than an everyday pound because it holds only 12 ounces.
| Ounce | Grams | Pound | Used for |
|---|---|---|---|
| Avoirdupois ounce (everyday) | 28.3495 | 16 oz = 1 lb (453.6 g) | Food, post, body weight, almost everything |
| Troy ounce | 31.1035 | 12 oz t = 1 troy lb (373.2 g) | Gold, silver, platinum prices |
| Fluid ounce (volume, not weight) | — | — | Liquids: 29.57 mL (US) or 28.41 mL (UK) |
A shipment of "20 tons" could differ by more than 2 tonnes depending on which ton is meant. In the US a ton is 2,000 lb, the metric tonne is 1,000 kg, and the old British long ton is 2,240 lb.
| Ton | Pounds | Kilograms | Used in |
|---|---|---|---|
| Tonne (metric ton) | 2,204.6 | 1,000 | Most of the world, shipping, science |
| Short ton (US ton) | 2,000 | 907.2 | United States |
| Long ton (UK ton) | 2,240 | 1,016 | Historic UK, some shipping figures |
In the UK and Ireland, body weight is often given in stones and pounds. What is 70 kg?
Step 1: Convert to pounds
Step 2: Divide by 14 for whole stones
70 kg is 11 st 0.3 lb, usually rounded to "11 stone". Don't write it as 11.02 stone: the part after the decimal point is a fraction of a stone, not pounds.
Gold is priced per troy ounce. How many troy ounces are in a 100 g bar?
A 100 g bar holds 3.215 troy ounces, so its metal value is 3.215 × the quoted price per ounce. Using everyday ounces (100 ÷ 28.35 = 3.527) would overstate the gold content by about 10%.
| Kilograms | Pounds | Stones and pounds |
|---|---|---|
| 1 kg | 2.2 | — |
| 5 kg | 11.02 | — |
| 10 kg | 22.05 | 1 st 8 lb |
| 25 kg | 55.12 | 3 st 13.1 lb |
| 50 kg | 110.23 | 7 st 12.2 lb |
| 60 kg | 132.28 | 9 st 6.3 lb |
| 70 kg | 154.32 | 11 st 0.3 lb |
| 80 kg | 176.37 | 12 st 8.4 lb |
| 90 kg | 198.42 | 14 st 2.4 lb |
| 100 kg | 220.46 | 15 st 10.5 lb |
About 2.20462. Exactly, 1 kg = 1 ÷ 0.45359237 lb.
14. A stone is about 6.35 kg.
Yes, for gemstones: 1 carat is exactly 0.2 g. Gold purity "karats" (such as 18K) are a different measure: the share of gold out of 24 parts.
Bullets and gunpowder, arrows, and some medicine and supplement doses. A grain is 64.79891 mg, and the same grain underlies the avoirdupois and troy systems (7,000 grains to the pound, 480 to the troy ounce).
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