How weight conversion works
Each unit in the converter is stored as an exact number of kilograms, and every conversion goes through that ratio:
Strictly speaking these are units of mass, which is what scales measure. The pound has been defined as exactly 0.45359237 kg since the 1959 international yard and pound agreement, and UK law uses the same figure, so kilogram–pound conversions are exact.
Key factors
| Unit | Equals | Notes |
|---|---|---|
| 1 pound (lb) | 0.45359237 kg | Exact |
| 1 ounce (oz) | 28.349523125 g | 1/16 lb, exact |
| 1 stone (st) | 6.35029318 kg | 14 lb |
| 1 US ton | 907.18474 kg | 2,000 lb (short ton) |
| 1 UK ton | 1,016.0469088 kg | 2,240 lb (long ton) |
| 1 tonne (t) | 1,000 kg | Metric ton |
| 1 grain (gr) | 64.79891 mg | Exact |
| 1 troy ounce | 31.1034768 g | Precious metals |
| 1 carat | 200 mg | Gemstones |
| 1 tola | 11.6638038 g | 180 grains |
Worked examples
- Body weight: 70 kg ÷ 0.45359237 = 154.32 lb, which is 11 stone 0.3 lb (154.32 ÷ 14 = 11 st, remainder 0.32 lb).
- Cooking: a 250 g pack of butter is 250 ÷ 28.3495 = 8.82 oz, a little over half a pound.
- Gold: a 10-tola bar is 10 × 11.6638038 = 116.64 g, or 3.75 troy ounces.
- Freight: 5 US tons = 10,000 lb = 4,535.9 kg, while 5 tonnes is 5,000 kg.
Tola, masha and ratti
Gold and silver in Pakistan, India, Nepal and much of the Gulf are still priced per tola. The tola was fixed in British India by Regulation VII of 1833 at 180 troy grains, the weight of a silver rupee, which is 11.6638038 g. Its metric equivalents were set out when India adopted the metric system under the Standards of Weights and Measures Act, 1956.
The traditional subdivisions are:
- 1 tola = 12 masha, so a masha is about 0.972 g.
- 1 masha = 8 ratti, so a goldsmith’s ratti is about 0.1215 g and a tola is 96 ratti.
Gem sellers often use a different, larger ratti (sometimes called the pakki ratti) of about 0.18 g. This converter uses the goldsmith’s ratti; for gemstones, ask which ratti your seller means, or work in carats.
Seer and maund: the British Indian seer is 80 tola (about 933.1 g) and the maund 40 seers (about 37.32 kg). In grain markets in Pakistan and Bangladesh today a maund usually means 40 kg, so both versions are listed.
Ounces: avoirdupois and troy
The ounce on a food label is the avoirdupois ounce, 28.35 g. Precious metals use the troy ounce, 31.10 g, about 10% heavier. A troy pound has only 12 troy ounces, which makes it lighter than an ordinary pound. Gold prices quoted “per ounce” always mean troy ounces.
Tips
- Stone and pounds: UK and Irish body weights are often written like “11 st 7 lb”. Use the stone-and-pounds box to convert straight to kilograms.
- Tons: check whether a document means a US ton, a UK ton or a metric tonne. The difference between them is up to 12%.
- Precision: choose “Auto” to see up to 10 significant digits, or pick 1–2 decimals for everyday use.
To check what a weight means for your health, use the BMI calculator. For heights and distances, open the length converter, and for cups, litres and gallons the volume converter.