Updated October 9, 2026
Weight Converter
Convert between milligrams, grams, kilograms, tonnes, ounces, pounds and stone. Type an amount, pick the units, get the answer instantly.
How the conversion works
Every unit is defined as an exact number of kilograms: 1 pound is 0.45359237 kg exactly, 1 ounce is 1/16 of a pound (28.349523125 g) exactly, 1 stone is 14 pounds exactly. Your amount is converted to kilograms first, then to the target unit.
Worked example
Convert 150 pounds to kilograms: 150 × 0.45359237 = 68.0388555 kg.
Mass vs weight
Strictly speaking, kilograms measure mass and pounds measure force, but in everyday language and commerce both are used as units of weight. This converter follows the everyday convention, like bathroom and kitchen scales do.
Planning estimate only. Results use the list prices shown and may differ from your actual bill. Terms
Frequently asked questions
How many kilograms are in a pound?
0.45359237 kg, exactly, by international definition since 1959.
What is a stone in weight?
14 pounds, or 6.35029318 kg exactly. It is still the everyday unit for body weight in the UK and Ireland.
How many grams are in an ounce?
28.349523125 grams, exactly one sixteenth of a pound.
Is a tonne the same as a ton?
Yes. The tonne (1,000 kg) is the metric ton; the US ton (2,000 lb) and UK long ton (2,240 lb) are not included, since tonne is the unambiguous metric unit.