To convert pounds (lbs) to kilograms (kg), use the precise conversion factor: 1 pound is exactly equal to 0.45359237 kilograms. The formula to convert pounds to kilograms is:

kg=lbs×0.45359237\text{kg}=\text{lbs}\times 0.45359237kg=lbs×0.45359237

For example, if you have 10 pounds and want to convert it to kilograms:

10 lbs×0.45359237=4.5359237 kg10,\text{lbs}\times 0.45359237=4.5359237,\text{kg}10lbs×0.45359237=4.5359237kg

This conversion is used worldwide to switch from the imperial system (pounds) to the metric system (kilograms). For quick mental approximation, you can halve the pounds value and subtract about 10% of that half, but the exact calculation uses the factor 0.45359237. This conversion is important for accuracy in science, medicine, travel, and many other fields where standard metric units are preferred.