Kilogram vs pound — body weight around the world
One kilogram = how many pounds? Plus the hidden stone unit you meet in the UK.
1 kg = 2.2046 lb (SI base)
1 lb = 0.4536 kg (US body weight, food)
One kilogram = 2.20462262 pounds. The pound is defined as exactly 0.45359237 kilograms (an international avoirdupois pound; there are other historical pounds with slightly different masses).
The pound is widely used in:
- US body weight — 154 lb = ~70 kg - US food packaging — often both units side by side - US postal/express weight — pounds and ounces - UK body weight — actually quoted in stone (14 lb), e.g., 11 stone 4 = 158 lb - UK food packaging — mostly metric since the 1990s, but some legacy products still exist
Body mass index (BMI) is sometimes computed on US medical forms as a magic-number in pounds; conversion is implied.
A trap: pound-force vs pound-mass. The pound you see on a body-weight scale is pound-mass. If you ever work in US engineering, distinguish them — pound-force is a unit of force, defined as the force of gravity on one pound-mass at standard gravity.
Frequently Asked Questions
Which should I use?
Use kilograms for science, recipes, and everywhere outside the US.
When is the alternative better?
Use pounds for US body weight, food packaging, and small-package shipping.
How is the conversion calculated?
Every conversion is a single factor (or an affine formula). The math is identical either direction; the difference is context.