How to convert pounds to kilograms
To convert pounds to kilograms, multiply each value by the exact factor in the box: 1 pound = 0.45359237 kilograms exactly (the international avoirdupois definition). There is no rounding anywhere in the chain — the display trims the final answer to six decimal places, and converting the result back with the inverse page returns your starting number.
The pound used here is the international avoirdupois pound, defined since 1959 as exactly 0.45359237 kilograms — not an approximation, but the legal definition agreed by the English-speaking world. Sixteen ounces make one pound, and 2,000 pounds make a US short ton. The kilogram it converts into is the metric base unit used by science, medicine and almost every country outside the United States, which is why an American weight so often needs translating.
The everyday jobs are body weight meeting a metric form (a 150 lb person is 68.04 kg on a medical chart), parcels priced by the kilogram, gym dumbbells labelled in pounds against a training app set to metric, and luggage: a 50 lb checked bag is 22.68 kg, comfortably under a 23 kg allowance, while a 55 lb bag at 24.95 kg is not. Newborn weights are another classic — 7 lbs 8 oz is 3.40 kg, the figure the rest of the world will write down.
The common mistake is using 0.45 or “just under half” as the factor: at 200 lbs that shortcut reads 90 kg against the true 90.7185 kg, an error big enough to misprice freight or misread a dosage chart. A subtler trap is the troy pound used historically for precious metals (0.373 kg) — it is not the pound on your scale, and this converter does not use it. Every figure here is multiplied by the exact 0.45359237.
Worked example
22 pounds is 9.979032 kilograms: 22 × 0.45359237 = 9.979032 — just under the 10 kg cabin-bag limit used by many airlines, which is exactly the kind of borderline this converter exists to settle.
How to use this converter
- Enter your value in pounds in the box above — the result updates as you type.
- Read the converted value in kilograms in the headline panel.
- Check the factor, the formula and the inverse result (your answer converted back) in the stats if you need to show your working.
- Use the Pounds to Kilograms conversion table below for other common values without typing each one.