Kilograms vs Pounds
Side-by-side comparison, when-to-use-each guide, and instant conversion. Reviewed for 2026.
Almost everywhere outside the US — Europe, most of Asia, Latin America, Africa. Universal in science, medicine, and sports (Olympic weightlifting).
United States (universal), UK (everyday weight for people and groceries), Liberia, Myanmar. Aviation worldwide still uses pounds for fuel and cargo.
| Aspect | Kilograms | Pounds |
|---|---|---|
| Definition | SI base unit since 1889 | 0.45359237 kg by international agreement (1959) |
| Symbol | kg | lb / lbs |
| Common use | Body weight (most countries), gym weights, scientific | Body weight (US/UK), groceries (US), aviation |
| 1 unit equals | 2.2046 lbs | 0.45359 kg |
| Origin | Defined by the kilogram prototype until 2019, now by Planck's constant | Roman libra; standardised internationally in 1959 |
Frequently asked
Is 1 kg exactly 2.2 lbs?
No — 1 kg is 2.2046 lbs. Using 2.2 introduces a 0.2% error, which matters for medical dosing and freight.
Which is heavier, 1 kg or 1 lb?
1 kg is heavier — approximately 2.205 times heavier than 1 lb. To convert: 1 kg = 2.205 lbs; 1 lb = 0.4536 kg. A 100 kg person weighs 220.5 lbs. For body weight, 10 stone = 63.5 kg = 140 lbs.
Why does the UK still use pounds?
The UK is technically metric (since 1965 in trade) but kept pounds for body weight, milk, beer and roadside distances. It's tradition, not regulation.