Weight Converter

How to use it

Type a weight, choose the unit it is in and the unit you want, then press Calculate. You can type decimals, fractions such as 3/8, mixed numbers such as 1 1/2, very large or small numbers such as 2.5e6, and simple sums such as 2*3. Swap exchanges the two units.

The answer is worked out exactly and only rounded for display, to 12 significant figures. Below it you get the same value in every other unit on the list, and Show the working gives the conversion factor that was used. Pounds and ounces here are the everyday avoirdupois units.

Weight or mass?

Strictly, pounds and kilograms measure mass, the amount of matter in something, while weight is the force of gravity on it. In everyday use, and on scales, the words mean the same thing, and that is what this converter does. It converts mass units; it does not convert between mass and force units such as newtons.

1 lb = 0.45359237 kg (exact)
1 lb = 16 oz
1 stone = 14 lb
1 short ton = 2,000 lb; 1 long ton = 2,240 lb
1 metric ton = 1,000 kg
1 carat = 200 mg

Three different tons

In the United States a ton normally means the short ton of 2,000 pounds. The British long ton is 2,240 pounds, and the metric ton, or tonne, is 1,000 kilograms (about 2,204.6 pounds). Because they differ by up to 12%, check which one a document means before converting.

Why calories are not listed

Some converters list calories as if they were a weight, using the rule of thumb that a pound of body fat stores about 3,500 kilocalories. Calories measure energy, not mass, and that rule is only a rough estimate that often misleads. We leave it out of this converter; a clearly labelled body-weight estimate belongs with the health calculators.

Questions