Weight & mass converter
Convert kilograms, grams, and tonnes to and from pounds, ounces, and stones, instantly and entirely in your browser. Nothing is uploaded.
The amount to convert. Leave empty or non-numeric for no result.
Metric and imperial mass, exactly
Weight and mass come in two systems people move between daily: metric (milligrams, grams, kilograms, tonnes) and imperial (ounces, pounds, stones). Each imperial unit is defined as an exact metric value — a pound is precisely 453.59237 g — so this converter steps between them without the drift of remembered approximations. Pick any two units and convert in either direction.
Runs entirely on your device
There is no server, no account, and no upload. The math is a few lines of JavaScript that execute in your browser, so the tool works offline and your figures stay private, whether you are weighing a recipe, a parcel, or yourself.
Frequently asked questions
- Does this send my data anywhere?
- No. The converter is plain JavaScript that runs entirely in your browser. There is no upload, no network request, and no account. The numbers you type never leave your device.
- How many grams are in a pound?
- Exactly 453.59237. The pound is defined as 453.59237 grams, and an ounce is one-sixteenth of that (28.349523125 g). The converter uses these exact definitions, so 1 lb = 16 oz comes out exactly.
- How many pounds are in a stone?
- 14. A stone is 6350.29318 grams, which is exactly 14 pounds, the unit still common for body weight in the UK and Ireland.
- What is the difference between weight and mass?
- In everyday use the words are interchangeable, and these units (grams, kilograms, pounds, ounces, stones, tonnes) all measure mass. True weight is a force that depends on gravity; on Earth's surface the distinction does not affect these conversions.
- How precise are the results?
- Imperial units are defined as exact metric values (1 lb ≡ 453.59237 g), so conversions are exact within floating-point limits. Long fractional results are rounded to twelve significant figures for readability.