Weight converter — kg to lbs, stones, ounces and grams

How to use the weight converter

1. Type the amount in Value, for example your body weight or a parcel’s weight.
2. Set From to the unit on your scale or label.
3. Set To to the unit you need, such as pounds or grams.
4. Read the result. For weights up to 1,000 kg, a Mixed units box also shows stones and pounds, and pounds and ounces.
5. Press the swap button to flip the two units.

What it does and when to use it

It converts mass between 13 units: tonnes, kilograms, grams, milligrams and micrograms; pounds, ounces and stones; US short tons and UK long tons; and the specialist troy ounce, carat and grain. People use it to translate a gym or doctor’s reading into the unit they know, to price postage, to follow a recipe written in ounces, or to compare the weight of a gold coin with its stated troy weight.

Everyday speech says “weight”, but scales report mass, which does not change with gravity. All conversions here are mass conversions, so they hold anywhere. If you are tracking body weight, the BMI calculator accepts kilograms or pounds. For distances, the length converter is built the same way.

How it works

Each unit is stored as a number of kilograms. The tool multiplies your value by the kilograms in the starting unit, then divides by the kilograms in the target unit.

The imperial units all come from one exact definition, the international pound of 1959:

• 1 pound = 0.45359237 kg
• 1 ounce = 1/16 pound = 28.349523125 g
• 1 stone = 14 pounds = 6.35029318 kg
• 1 grain = 1/7,000 pound; 1 troy ounce = 480 grains = 31.1034768 g
• 1 carat = 0.2 g exactly

For the mixed figures, the tool takes the total in pounds, splits off whole stones (or whole pounds) and shows the rest to four significant digits.

Worked examples

These are the converter’s own results.

Body weight in the UK and US. 70 kg = 154.323583529 pounds. The mixed box shows 11 st 0.3236 lb and 154 lb 5.177 oz, so you would say “11 stone” in Britain or “154 pounds” in the US.

A recipe in ounces. 8 oz = 226.796185 grams, so a half-pound pack of butter is about 227 g.

A gold coin. 1 troy ounce = 31.1034768 grams, compared with 28.35 g for a kitchen ounce.

Limits and tips

• The mixed-units box is hidden for zero, negative values and anything over 1,000 kg, where stones are not a useful unit.
• The karat (gold purity) is not the carat (gem mass). Only the gem carat of 0.2 g is here.
• Recipes that give cups of flour need the ingredient’s density, which a mass converter cannot know. The cooking converter sorts out US, metric and other cup sizes, but it converts volume, not grams.
• Results are rounded to 12 significant digits; the factors themselves are exact.