Weight Converter
Metric & Imperial · 9 units
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Weight & Mass Quick Reference
One pound is exactly 0.45359237 kilograms, so 1 kg is about 2.20462 lb. The ounce is 1/16 of a pound, 28.349523125 grams, and a stone is 14 pounds. Type a weight above, choose the units, and the converter shows the answer in all nine units, from milligrams to long tons.
Exact conversion factors based on international definitions. The pound was redefined in 1959 as exactly 0.45359237 kilograms.
| From | To | Multiply by |
|---|---|---|
| pounds (lb) | kilograms (kg) | 0.45359237 (exact) |
| kilograms (kg) | pounds (lb) | 2.20462 |
| stone (st) | kilograms (kg) | 6.35029318 (exact) |
| ounces (oz) | grams (g) | 28.349523125 (exact) |
| grams (g) | ounces (oz) | 0.035274 |
| metric ton (t) | pounds (lb) | 2204.62 |
The stone unit is used mainly in the UK and Ireland for body weight. 1 stone = 14 pounds = 6.35 kg. In everyday US life body weight and groceries are in pounds, although labels, medicine and science also use grams; most of the rest of the world uses kilograms.
Pounds and Kilograms Conversion Tables
Rounded to two decimals, computed from 1 lb = 0.45359237 kg.
| Pounds | Kilograms | Kilograms | Pounds |
|---|---|---|---|
| 1 lb | 0.45 | 1 kg | 2.20 |
| 5 lb | 2.27 | 5 kg | 11.02 |
| 10 lb | 4.54 | 10 kg | 22.05 |
| 20 lb | 9.07 | 20 kg | 44.09 |
| 50 lb | 22.68 | 50 kg | 110.23 |
| 100 lb | 45.36 | 60 kg | 132.28 |
| 120 lb | 54.43 | 70 kg | 154.32 |
| 150 lb | 68.04 | 80 kg | 176.37 |
| 180 lb | 81.65 | 90 kg | 198.42 |
| 200 lb | 90.72 | 100 kg | 220.46 |
| 250 lb | 113.40 | 120 kg | 264.55 |
| 300 lb | 136.08 | 150 kg | 330.69 |
Ounces and Grams for the Kitchen
These are weight ounces (avoirdupois), the ones on food labels and kitchen scales. Fluid ounces measure volume and belong on the volume converter.
| Ounces | Grams | Grams | Ounces |
|---|---|---|---|
| 0.5 oz | 14.17 | 50 g | 1.76 |
| 1 oz | 28.35 | 100 g | 3.53 |
| 2 oz | 56.70 | 125 g | 4.41 |
| 4 oz | 113.40 | 250 g | 8.82 |
| 8 oz | 226.80 | 500 g | 17.64 |
| 12 oz | 340.19 | 1,000 g | 35.27 |
| 16 oz (1 lb) | 453.59 | 2,000 g | 70.55 |
Tons, Stones and Troy Ounces
Several weight units share a name but not a size. The converter above uses the avoirdupois system for ounces and pounds.
| Unit | Definition | Exact metric value |
|---|---|---|
| US short ton | 2,000 lb | 907.18474 kg |
| UK long ton | 2,240 lb | 1,016.0469088 kg |
| Metric ton (tonne) | 1,000 kg | 2,204.62 lb (rounded) |
| Stone | 14 lb | 6.35029318 kg |
| Troy ounce | 480 grains | 31.1034768 g |
| Troy pound | 12 troy oz | 373.2417216 g |
A troy ounce is about 9.7% heavier than an ordinary ounce, but a troy pound (12 troy ounces) is lighter than an ordinary pound (16 ounces): it equals 0.823 lb.
Weight Conversion Mistakes to Avoid
- Treating 2.2 as exact. 1 kg is 2.20462 lb. Dividing 200 lb by 2.2 gives 90.91 kg against a true 90.72 kg, an error of about 0.2%. Fine for a quick check, not for shipping weights or medicine.
- Confusing ounces and fluid ounces. 8 oz of flour is a weight; 8 fl oz is a cup of volume. Only for water do the two come close.
- Using the wrong ton. A US freight quote in tons means 2,000 lb, a UK one may mean 2,240 lb, and most of the world means 1,000 kg. On 20 tons the gap between short and metric tons is 1.86 metric tons.
- Weighing gold in ordinary ounces. Precious metal prices are per troy ounce, 31.1034768 g, not 28.35 g.
Method and sources. Factors from NIST Special Publication 811 (Appendix B) and NIST Handbook 44 (Appendix C): 1 lb (avoirdupois) = 0.45359237 kg exactly under the 1959 international yard and pound agreement; 1 oz = 1/16 lb; 1 stone = 14 lb; short ton = 2,000 lb; long ton = 2,240 lb; 1 grain = 64.79891 mg exactly, troy ounce = 480 grains. Every table value was computed from these exact factors and rounded only at the end.
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Weight Conversion Questions
One pound equals exactly 0.45359237 kilograms, by international definition since 1959. Conversely, 1 kilogram = 2.20462 pounds. To convert pounds to kg, multiply by 0.4536. To convert kg to pounds, multiply by 2.2046. Example: 150 lb = 68.04 kg · 80 kg = 176.37 lb.
One stone equals exactly 14 pounds = 6.35029 kilograms. Stone is primarily used in the UK and Ireland to measure body weight. To convert stone to kg, multiply by 6.35. Example: 11 stone = 154 lb = 69.85 kg · 13 stone = 182 lb = 82.55 kg. To convert kg to stone, divide by 6.35.
One avoirdupois ounce equals exactly 28.349523125 grams (about 28.35 g). There are 16 ounces in one pound. To convert ounces to grams, multiply by 28.35. To convert grams to ounces, divide by 28.35 (or multiply by 0.035274). Note: the troy ounce used for precious metals is different: 1 troy oz = 31.1035 g.
Mass is the amount of matter in an object, measured in kilograms (SI). Weight is the gravitational force acting on that mass, measured in newtons. On Earth's surface they are proportional: 1 kg of mass weighs about 9.81 newtons. In everyday usage, "weight" and "mass" are used interchangeably, and a bathroom scale measures the force you press down with and displays it as mass in kg or lb. On the Moon you would weigh about one sixth as much, but your mass would be unchanged.
Divide your kg weight by 6.35029 to get stone as a decimal. The whole number is the stone. Multiply the decimal remainder by 14 to get the pounds. Example: 75 kg ÷ 6.35029 = 11.811 stone = 11 stone 11.4 lb. Common conversions: 60 kg = 9 st 6 lb · 70 kg = 11 st 0 lb · 80 kg = 12 st 8 lb · 90 kg = 14 st 2 lb.
There are exactly 16 ounces in one pound (avoirdupois system). One pound = 453.592 grams = 16 oz. One ounce = 28.3495 grams. This is the system used for everyday goods in the US and UK. Note that the troy system used for precious metals is different: 1 troy pound = 12 troy ounces, and a troy ounce is heavier than an avoirdupois ounce.
One metric ton (also called a tonne) = 1,000 kilograms = 2,204.62 pounds. Note the difference between a metric ton (1,000 kg), a US short ton (2,000 lb = 907.185 kg), and a UK long ton (2,240 lb = 1,016.05 kg). In most international trade and scientific use, "ton" means the metric ton unless specified otherwise.
A milligram (mg) is one thousandth of a gram (0.001 g) or one millionth of a kilogram. 1 mg = 0.001 g = 0.000001 kg. Milligrams are used for pharmaceutical dosages (for example a 500 mg acetaminophen tablet), nutritional labels (e.g. sodium, vitamins), and chemistry. A low-dose aspirin tablet contains 81 mg of aspirin, and a US paper bill weighs about 1 gram, or 1,000 mg.
Divide grams by 453.592 to get pounds as a decimal. The whole number is the pounds. Multiply the decimal remainder by 16 to get the ounces. Example: 500 g ÷ 453.592 = 1.1023 lb = 1 lb 1.64 oz. Common cooking conversions: 100 g = 3.53 oz · 250 g = 8.82 oz · 500 g = 17.64 oz · 1 kg = 2 lb 3.27 oz.
The troy ounce (ozt) is a unit of mass used for precious metals (gold, silver, platinum). 1 troy oz = 31.1035 grams, which is heavier than the avoirdupois ounce (28.3495 g) used for everyday goods. Gold and silver prices in the US are quoted per troy ounce. 1 troy pound = 12 troy ounces = 373.24 g. Our converter uses the standard avoirdupois ounce; for precious metals, multiply the troy oz value by 31.1035 to get grams.
For everyday use, yes. The exact factor is 2.20462 lb per kg, so 2.2 is about 0.2% low: 100 kg becomes 220 lb instead of 220.46 lb. For medication doses, shipping and anything billed by weight, use the full factor or the converter above.
A pound is exactly 453.59237 grams. Half a pound is 226.8 g and a quarter pound is 113.4 g, which is why a quarter-pound burger patty is listed as about 113 g before cooking.