How the Weight Converter Works
Weight is measured in different units around the world. Most countries use the metric system, with grams and kilograms. The United States uses ounces and pounds, and in the United Kingdom people often give body weight in stone. The Weight Converter changes a weight from one unit into another, and shows the same weight in every unit at once.
What you enter
- The weight: a number, which can have decimals.
- The unit you have (From): milligrams, grams, kilograms, metric tons, ounces, pounds, stone or US tons.
- The unit you want (To): any of the same units. The swap button reverses the two.
How the conversion works
Every unit has a fixed size in kilograms. The converter turns your weight into kilograms, and then turns the kilograms into the unit you chose:
kilograms = weight x kilograms in the From unit result = kilograms / kilograms in the To unit
These are the exact sizes of the units, which have been set by international agreement:
| Unit | Size in kilograms | Size in pounds |
|---|---|---|
| 1 milligram (mg) | 0.000001 | 0.0000022046 |
| 1 gram (g) | 0.001 | 0.0022046 |
| 1 kilogram (kg) | 1 | 2.2046226 |
| 1 metric ton (t) | 1,000 | 2,204.6226 |
| 1 ounce (oz) | 0.028349523125 | 0.0625 |
| 1 pound (lb) | 0.45359237 | 1 |
| 1 stone (st) | 6.35029318 | 14 |
| 1 US short ton | 907.18474 | 2,000 |
A pound is exactly 16 ounces, a stone is exactly 14 pounds, and a US ton is exactly 2,000 pounds. A metric ton is 1,000 kilograms, and it is a little more than a US ton.
A worked example
You want to change 150 pounds into kilograms.
| Step | Value |
|---|---|
| Pounds to kilograms (150 x 0.45359237) | 68.0388555 kg |
| Rounded to 7 digits | 68.03886 kg |
The same 150 pounds in other units:
| Unit | Amount |
|---|---|
| Milligrams | 68,038,860 mg |
| Grams | 68,038.86 g |
| Kilograms | 68.03886 kg |
| Metric tons | 0.06803886 t |
| Ounces | 2,400 oz |
| Stone | 10.71429 st, or 10 st 10 lb |
| US short tons | 0.075 ton |
Doing it by hand
- Pounds to kilograms: multiply by 0.4536, or divide by 2.2046. So 100 lb is 45.36 kg.
- Kilograms to pounds: multiply by 2.2046. So 100 kg is 220.46 lb.
- Ounces to grams: multiply by 28.35. So 8 oz is 226.8 g.
- Grams to ounces: divide by 28.35. So 250 g is 8.82 oz.
A quick estimate: to change kilograms to pounds, double the number and add 10%. For 50 kg, double is 100, and 10% of that is 10, so about 110 lb. The exact answer is 110.23 lb.
Pounds to kilograms
| Pounds | Kilograms |
|---|---|
| 1 | 0.45 |
| 5 | 2.27 |
| 10 | 4.54 |
| 25 | 11.34 |
| 50 | 22.68 |
| 100 | 45.36 |
| 150 | 68.04 |
| 200 | 90.72 |
5 lb ██ 2.27 kg 10 lb ████ 4.54 kg 25 lb ██████████ 11.34 kg 50 lb ████████████████████ 22.68 kg 100 lb ████████████████████████████████████████ 45.36 kg
Pounds and kilograms are different sizes, so the kilogram number is always smaller. A kilogram is about 2.2 pounds.
Kilograms and pounds side by side
The green bar is the weight in kilograms, and the blue bar is the same weight in pounds.
10 kg ██ ████ 22.05 lb 25 kg █████ ██████████ 55.12 lb 50 kg █████████ ████████████████████ 110.23 lb 100 kg ██████████████████ ████████████████████████████████████████ 220.46 lb
Pounds and ounces, stone and pounds
People often write weights in two parts. When the answer is in pounds, the converter also shows it as pounds and ounces. When it is in stone, it shows stone and pounds. For example:
- 1 kilogram is 2.2046 pounds, or 2 lb 3.27 oz.
- 70 kilograms is 11.02 stone, or 11 st 0.32 lb.
- 68 kilograms is 10.71 stone, or 10 st 9.91 lb.
Where these conversions are used
- Cooking: recipes may give ounces or grams. 8 oz of butter is 226.8 g.
- Travel: many airlines allow a bag of 23 kg, which is 50.7 lb. A 50 lb limit is 22.68 kg.
- Health: body weight is given in kilograms, pounds or stone, depending on the country.
- Shipping and trade: prices per pound or per kilogram, and loads in tons.
- Science: small amounts in milligrams and grams.
Tips
- Check which ton you mean. A US short ton is 2,000 lb (907.18 kg), and a metric ton is 1,000 kg (2,204.62 lb). The old UK ton is different again, at 2,240 lb, and it is not included here.
- Do not confuse weight and volume. An ounce of weight is not a fluid ounce. To change volume, use a volume converter.
- Use enough digits for small amounts. The converter shows up to 7 significant digits, so that small amounts do not round to zero.
What this converter does not include
- Volume, length and other kinds of units.
- Troy ounces, used for gold and silver, and other special units, such as carats.
- The UK long ton.
This tool gives an estimate for general information only. For medicine, science or trade that needs a legal weight, use a calibrated scale and follow the official rules.