Weight
Mass units worldwide
The Weight Converter handles the most common mass units used worldwide: grams, kilograms, ounces, pounds, and stones (still used for body weight in the UK). Like length, weight conversions get confusing because the imperial chain (ounces → pounds → stones) is not metric.
This tool runs both directions simultaneously: type a value in any field and all the others update instantly.
Supported units
- Metric: milligram (mg), gram (g), kilogram (kg), tonne (t)
- Imperial / US: ounce (oz), pound (lb), stone (st), US ton, UK long ton
Key conversion factors
- 1 pound = exactly 0.45359237 kilograms (international definition)
- 1 ounce = 1/16 pound ≈ 28.3495 grams
- 1 stone = 14 pounds ≈ 6.3503 kilograms
- 1 kilogram = 1000 grams = 2.20462 pounds
- 1 tonne (metric) = 1000 kilograms ≈ 2204.62 pounds
The international avoirdupois pound has been defined as exactly 0.45359237 kg since 1959, so all conversions derive from that.
Worked example
Convert 12 stone 4 pounds to kilograms:
- Convert to pounds:
12 × 14 + 4 = 172 pounds - Convert to kg:
172 × 0.45359 ≈ 78.02 kg
Or convert 250 g to ounces: 250 / 28.3495 ≈ 8.82 oz.
When to use this
Cooking from recipes in another measurement system, fitness tracking, shipping packages internationally, and travel (luggage weight limits are typically given in kg even by US airlines for international flights).
Mass vs weight
Technically, "mass" (kg, g) is the amount of matter and "weight" is the force exerted by gravity on that mass. On Earth they are proportional, so for everyday purposes the two terms are used interchangeably. A scale that reads in kilograms is actually measuring weight and converting using Earth's gravity.
Frequently asked questions
How many pounds in a kilogram?
Approximately 2.20462 pounds. A handy mental rule: kg × 2.2 ≈ lb.
What is a stone?
A unit of mass equal to 14 pounds (about 6.35 kg), still commonly used for body weight in the UK and Ireland.
Is the US ton the same as a UK ton?
No. The US (short) ton is 2,000 pounds. The UK (long) ton is 2,240 pounds. The metric tonne is 1,000 kg ≈ 2,204.6 pounds. Always specify which.