The Formula
kg = lb × 0.45359237
A pound is a bit less than half a kilogram — exactly 0.45359237 kg, the definition fixed by international agreement in 1959. The example above: 150 lb × 0.4536 = 68 kg.
The Mental Shortcut
Halve the pounds, then subtract 10% of that: 180 lb → 90 − 9 = 81 kg (exact: 81.6). The halving alone overshoots by ~10%, and the correction brings you within a kilogram — plenty for reading American body weights, recipes, or shipping specs.
Where This Conversion Shows Up
Reading American content is the main driver: a “200-pound man” is ~91 kg, a “10-pound turkey” is 4.5 kg, and US shipping quotes in lb need conversion for the rest of the world’s scales. In the gym, US plates of 45 lb are the ~20 kg standard elsewhere — a “225 bench” (two plates per side) is 102 kg. US package limits: the 70 lb parcel cap converts to 31.75 kg.
Frequently Asked Questions
How many kg is 1 pound exactly?
0.45359237 kg — exact by definition, not approximation. Every conversion on this page derives from that single fixed number.
What is 150 lbs in kg and stones?
150 lb = 68.04 kg = 10 stone 10 lb. For all units side by side, use our Weight Converter.
Are US pounds and UK pounds the same?
Yes — both use the international avoirdupois pound (0.45359237 kg). The difference is usage: the UK quotes body weight in stones and pounds, the US in pounds alone.
How much is a "quarter-pounder" in grams?
A quarter pound is 113.4 g — the famous burger weight before cooking. Handy anchor: 1 oz ≈ 28 g, and a quarter pound is 4 oz.