What is weight converter?
A weight converter changes mass between units such as kilograms and pounds. It is useful for cooking, travel luggage, fitness, shipping and science.
Strictly, kilograms measure mass and pounds can measure mass or force, but in daily life both are called weight, and the tool converts mass.
How to use the weight converter
- Enter the value.
- Choose the unit you have and the unit you want.
- Read the result and the table of all units.
How the weight converter works
Each value is converted to kilograms using exact factors: one pound is 0.45359237 kg, one ounce is 0.028349523125 kg and one stone is 6.35029318 kg. The result is then divided by the target unit.
Worked example
Common uses of the weight converter
- Luggage limits.
- Recipes and baking.
- Fitness and body weight.
- Shipping and freight.
- Science homework.
Tips and common mistakes
Airlines often limit luggage in kilograms, so convert your scale reading before you travel.
Use the table to compare many units at once.
Background: what to know before you rely on it
The kilogram was long defined by a platinum iridium cylinder kept in France, and since 2019 it is defined by a fixed value of the Planck constant, which makes it stable for all time. The pound has a long history of regional variants, and in 1959 the English speaking countries agreed on the international pound of exactly 0.45359237 kg. The stone remains in use in the United Kingdom and Ireland for body weight. When cooking, remember that ounces of weight differ from fluid ounces of volume.
Private, free and fast
This tool runs entirely in your browser. What you type or choose is not uploaded to a server and is not saved after you close the page, which keeps it fast and private. It is free to use as often as you like. See more in all converters, or browse the full list of tools.
Frequently asked questions
How many pounds are in a kilogram?
About 2.2046.
How many grams are in an ounce?
About 28.35.
What is a stone?
A British unit equal to 14 pounds, about 6.35 kg.
Is the factor exact?
Yes. The pound is defined as exactly 0.45359237 kilograms.
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Results are for information and education. For legal, financial, medical or security decisions, check with a qualified professional. Check critical conversions with an official source.