Weight Converter

How this conversion works

Everyday “weight” units are units of mass. The kilogram is the SI base unit, and the international avoirdupois pound has been defined as exactly 0.45359237 kg since 1959. Ounces, stones and short and long tons are all exact multiples of that pound.

The converter expresses your value in kilograms and divides by the size of the target unit. Troy ounces, used for precious metals, are a separate system: one troy ounce is 31.1034768 g, heavier than an ordinary ounce.

Formula: result = value × (base units per source unit) ÷ (base units per target unit)

Where this conversion is used

• Body weight in kg, pounds or stones.
• Baggage allowances and shipping weights.
• Cooking by weight with gram or ounce recipes.
• Gym weights and plates labeled in kg or lb.

Worked example: 72 kg to pounds

1. One pound is 0.45359237 kg.
2. 72 ÷ 0.45359237 = 158.733 lb.
3. In stones and pounds: 158.733 ÷ 14 = 11 st with 4.73 lb left over.

Unit definitions

Things to watch for

• A US short ton is 2,000 lb, a UK long ton is 2,240 lb and a metric ton is 1,000 kg. They are three different units.
• Gold and silver prices quote troy ounces, not ordinary ounces.

Precision and sources

Results are calculated from the definitions above and rounded to 12 significant digits; the converter shows up to eight decimal places and the tables four. Reference: NIST Special Publication 811, Guide for the Use of the International System of Units, Appendix B.

Frequently asked questions