Weight & Mass
Convert between kilograms, grams, milligrams, metric tons, pounds, ounces and stones.
Weight Converter
Professional grade conversion for weight units.
Conversion Formula
1 Kilogram ≈ 1,000 Gram
What Weight & Mass does
What is commonly called weight is properly mass, and the units here are mass units. The distinction matters in physics but not in cooking, shipping or bodyweight, where these conversions are used.
As with length, the metric and imperial systems are tied together exactly: the international pound is defined as exactly 0.45359237 kilograms.
- Metric: metric ton, kilogram, gram, milligram
- Imperial: stone, pound, ounce
How to use Weight & Mass
- 1
Enter the value
Type the amount you want to convert. The result updates as you type.
- 2
Select the units
Choose what your value is in and what you want it in, for example kilograms to pounds.
- 3
Copy the result
The copy button gives you the unformatted number, without thousands separators, ready to paste into a spreadsheet or code.
When to use it
Following a recipe from another country
American recipes use ounces and pounds while European ones use grams.
Shipping and luggage limits
Airlines and couriers quote allowances in kilograms or pounds depending on the region.
Bodyweight in stones
Stones remain in everyday use in the UK and Ireland, where one stone is 14 pounds.
Limits and known behaviour
- The ounce here is the avoirdupois ounce of mass. A fluid ounce is a measure of volume and is a different quantity entirely; use the volume converter for that.
- Troy ounces, used for precious metals, are about 10% heavier than avoirdupois ounces and are not included.
- US and UK tons differ from the metric tonne offered here: a US short ton is 2000 pounds and a UK long ton is 2240.
- Arithmetic uses double-precision floating point, so a converted value can end in a small representation residue. That is a property of binary arithmetic, not of the conversion factor.
Privacy and data handling
Runs entirely in your browser
- The conversion is arithmetic performed in this page. Nothing you enter is transmitted or stored.
- The tool works offline once the page has loaded.
Site-wide data handling, including analytics and advertising, is described in the privacy policy.
Frequently asked questions
Is an ounce of gold the same as an ounce of flour?
No. Precious metals are measured in troy ounces of about 31.1 grams, while food is measured in avoirdupois ounces of about 28.35 grams. This converter uses the avoirdupois ounce.
How do I convert a recipe from cups to grams?
You cannot, with a unit converter alone. A cup measures volume, so the mass depends on the ingredient's density: a cup of flour and a cup of sugar have quite different weights.