Overview
Gyms, programs and scales don't agree on units: a US rack is marked in pounds, an Olympic bar is 20 kg, and most training articles quote kilos. This converter moves any number between the two with the exact legal factor, so your numbers stay comparable across sources.
How it's calculated
Enter an amount and pick the direction. Since 1959 the international pound has been defined as exactly 0.45359237 kg, so this is a definition, not an approximation — the only rounding happens at the second decimal in the displayed result. The preset chips cover the loads you meet most often: bumper plates, a 45 lb plate, and 135/225/315 lb bar totals.
kg = lb × 0.45359237 lb = kg ÷ 0.45359237
How to read your result
For mental math, divide pounds by 2.2 (or halve and subtract 10%) to get kilos, and multiply kilos by 2.2 to go back. That is accurate to under 1% — fine for picking a warm-up, not for a competition weigh-in. Use the exact result when you're logging a lift or reporting bodyweight.
Frequently asked questions
How many kg is 1 lb?
Exactly 0.45359237 kg. Going the other way, 1 kg is about 2.2046 lb.
Why don't gym plates match after converting?
Because plates are manufactured in whole units of each system, not converted. A 45 lb plate is 20.41 kg and a 20 kg plate is 44.09 lb, so a 'same' loaded bar differs by roughly 1–2% between a pound gym and a kilo gym.
Is an Olympic bar 20 kg or 45 lb?
A competition Olympic bar is 20 kg, which is 44.09 lb — not 45. Many US gyms sell a 45 lb bar (20.41 kg) instead. Check the stamp on your bar before you trust a rounded conversion.
Is 225 lb really 100 kg?
No — 225 lb is 102.06 kg, and 100 kg is 220.46 lb. The 'two plates' benchmark is 225 lb in the US and 100 kg elsewhere, so they are not the same lift.
Are pounds and pound-force the same here?
This converter handles mass, which is what scales and plates measure. Pound-force is a unit of force and is a different quantity — you won't need it for training numbers.