Mass & Weight
Pounds to kilograms
The exact conversion. One multiplication, with a factor that carries no measurement error of its own.
The Formula
kg = lb x 0.45359237
The exact conversion. One multiplication, with a factor that carries no measurement error of its own.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| lb | Weight in avoirdupois pounds | pounds | The pound used for body weight, groceries and shipping. Not the troy pound used for precious metals. |
| 0.45359237 | Kilograms per pound | kilograms per pound | Exact by the 1959 international agreement, so it never contributes rounding error. |
| kg | Mass in kilograms | kilograms | 180 lb gives 81.6466266 kg. |
What Each Symbol Means
lbpounds
Weight in avoirdupois pounds
The pound used for body weight, groceries and shipping. Not the troy pound used for precious metals.
0.45359237kilograms per pound
Kilograms per pound
Exact by the 1959 international agreement, so it never contributes rounding error.
kgkilograms
Mass in kilograms
180 lb gives 81.6466266 kg.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to convert pounds to kilograms page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Convert Pounds To Kilograms, filed under Unit Conversion. Every number the guide produces comes from substituting into this one line.