Ans

Unit converter

Pounds to kilograms.

Convert lb to kg and kg to lb. Type in either box and the other follows. The pound is defined as exactly 0.453 592 37 kg, so nothing here is approximated.

lb → kgExact definition
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Pounds to kilograms — common values, to 6 significant figures.
lbkg
1 lb0.453592 kg
2 lb0.907185 kg
5 lb2.26796 kg
10 lb4.53592 kg
20 lb9.07185 kg
50 lb22.6796 kg
100 lb45.3592 kg
150 lb68.0389 kg
200 lb90.7185 kg
250 lb113.398 kg
1 lb=0.45359237 kg 1 kg=2.204622622 lb

Definitions

  • The international avoirdupois pound is exactly 0.453 592 37 kg, agreed in 1959 — which is why pounds and kilograms convert exactly.
  • The kilogram is the SI base unit of mass, defined since 2019 by fixing the Planck constant rather than by a metal cylinder in Paris.
  • This conversion is exact by definition. 1 lb = 0.45359237 kg.
  • Everything here is mass, not force. The pound is defined as exactly 0.453 592 37 kg, so pound-to-kilogram conversion is exact.

How it works

One direction multiplies and the other divides by the same number, so nothing is lost by going back and forth.

The value passes through kg, the unit every other mass & weight unit on the site is defined against, rather than a number written into this page on its own. That is why the figure here, the figure in the table above and the general mass & weight converter always agree.

Display precision limits significant figures rather than decimal places, because one fixed number of decimals is useless across a range this wide. Very large and very small results switch to scientific notation with a proper superscript exponent. The editable box always holds a plain number at full working precision, so you can carry on from either side.

Common questions this answers: how many kilograms in a pound (0.453592), how many pounds in a kilogram (2.20462), and what 150 lb is in kilograms (68.0389 kg).

From the maker of Ans — a scientific calculator you can own. Same idea: a proper instrument, nothing in the way.