lbs to kg Converter — Pounds to Kilograms
Enter a weight in pounds and instantly get kilograms, grams, ounces, stones and tonnes — based on the exact international definition of the avoirdupois pound.
lbs
Exact definition: 1 lb = 0.45359237 kg (international avoirdupois pound)
- 1
Conversion factor
1 lb = 0.45359237 kgExact international avoirdupois definition (since 1959). - 2
Kilograms
150 × 0.45359237 = 68.0389
How does this calculator work?
Multiply pounds by 0.45359237 to get kilograms — the pound is defined as exactly that many kg (avoirdupois, since 1959). Divide kg by 0.45359237 (or multiply by 2.20462) to go the other way. Enter a weight above to also see grams, ounces, stones and tonnes.
Formula
How this is calculated
Since 1959 the international avoirdupois pound has been defined as exactly 0.45359237 kilograms. That single exact constant underpins every pounds-to-kilograms conversion, so there is no approximation in the formula itself — only rounding in the displayed result.
To convert pounds to kilograms, multiply by 0.45359237. To reverse the conversion, divide kilograms by the same constant (equivalent to multiplying by 2.20462...). Grams are kilograms × 1000, metric tonnes are kilograms ÷ 1000, and ounces are pounds × 16 (with 1 oz = 28.349523125 g exactly). One stone equals exactly 14 pounds, so the stone count is the whole-number quotient of pounds ÷ 14, with the remainder displayed in pounds.
This converter uses the avoirdupois pound — the standard for everyday commerce and body weight in the US and UK. There are other pound standards (troy pound = 373.24 g, used for precious metals; metric pound = 500 g, used in some European markets) but those are different systems not covered here.
Frequently asked questions
Exactly 0.45359237 kg. The international avoirdupois pound has been defined by this exact value since 1959. In practice 1 lb ≈ 0.454 kg or 454 g.
Divide pounds by 2.2 for a quick approximation — 100 lbs ÷ 2.2 ≈ 45.5 kg. For more accuracy, multiply by 0.4536. The exact factor is 0.45359237.
Both are units of mass. Pounds are the imperial unit used in the US and UK; kilograms are the SI metric unit used worldwide. One kilogram equals about 2.205 pounds, so kilograms are heavier — a 10 kg bag weighs about 22 lbs.
Also known as
TG we-Calculate Editorial Team. (2026). lbs to kg Converter — Pounds to Kilograms [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/lbs-to-kg-converter
TG we-Calculate Editorial Team. "lbs to kg Converter — Pounds to Kilograms." TG we-Calculate. 2026. https://we-calculate.com/calculator/lbs-to-kg-converter.
TG we-Calculate Editorial Team, "lbs to kg Converter — Pounds to Kilograms," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/lbs-to-kg-converter
@misc{wecalculate_lbs_to_kg_converter, title = {lbs to kg Converter — Pounds to Kilograms}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/lbs-to-kg-converter}}, year = {2026}, note = {TG we-Calculate} }
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