Weight and Mass Converter
Milligrams through tonnes in one tool. Mass, weight and force get mixed up a lot, so the page explains where they differ.
Most used weight tools
Kilograms to Pounds
With stones and pounds output and presets for common body weights.
Cups to Grams
Kitchen weights by ingredient.
Newtons to Pounds
Force rather than mass, where lbf and lb differ.
Convert every unit at once
Enter a number.
Every weight converter on this site
Reference table
| Unit | In kilograms | Exact? |
|---|---|---|
| 1 gram | 0.001 kg | Exact |
| 1 tonne | 1000 kg | Exact |
| 1 ounce (avoirdupois) | 0.028349523125 kg | Exact |
| 1 pound | 0.45359237 kg | Exact |
| 1 stone | 6.35029318 kg | Exact, 14 lb |
| 1 US ton | 907.18474 kg | Exact, 2000 lb |
| 1 troy ounce | 0.0311034768 kg | Exact, precious metals only |
Mass, weight and force
Strictly, everything above measures mass. Weight is a force, the pull of gravity on a mass, and its SI unit is the newton. On the Earth's surface the two are proportional, which is why a bathroom scale can be marked in kilograms and nobody minds.
It stops working when a calculation involves acceleration or a force rating. For that, the newtons to pounds converter handles pounds-force rather than pound-mass.
Two ounces, two different sizes
The everyday avoirdupois ounce is 28.35 grams. The troy ounce, used for gold and silver, is 31.10 grams, about 10 percent heavier. A price quoted per ounce for a precious metal means troy. This tool uses the avoirdupois ounce.
Common questions
What is the difference between mass and weight?
Mass is how much matter something contains and is measured in kilograms. Weight is the force gravity exerts on that mass and is measured in newtons. On the Earth's surface they are proportional, which is why bathroom scales can be marked in kilograms.
Is a troy ounce the same as a normal ounce?
No. The everyday avoirdupois ounce is 28.35 grams. The troy ounce, used for gold and silver, is 31.10 grams, about 10 percent heavier. This tool uses the avoirdupois ounce.
How many pounds are in a stone?
Fourteen pounds, exactly, which is 6.35029318 kilograms. The stone is defined as 14 pounds and the pound as exactly 0.45359237 kilograms, so both figures are definitions rather than measurements.
Is a US ton the same as a metric tonne?
No. A US ton is 2,000 pounds, or 907.18 kilograms. A metric tonne is 1,000 kilograms, roughly 10 percent heavier.
Sources
- NIST Guide to the SI, Appendix B: Conversion Factors. National Institute of Standards and Technology. Source for every conversion factor used by this tool, and for which factors are exact rather than rounded.