When it comes to measuring weight -- or more accurately, mass -- in the United States, people use pounds. But nearly every other country in the world uses kilograms. If you want to carry on a useful conversation with someone from another country -- or if you work in the sciences -- you'll need to know how to convert weights from pounds to kilograms.
To convert pounds into kilograms, divide the number of pounds you have by 2.2046. So if you have 20 pounds, that works out to 20 / 2.2046 or 9.0719 kilograms. For most everyday purposes, rounding to the hundredths place -- or in this case, 9.07 -- is sufficient for accuracy.
If you feel more comfortable using multiplication, you can do so -- but you'll need a different conversion factor. Multiply the weight you have in pounds by 0.454 to get the weight in kilograms. So if you have 65 pounds, that works out to 65 x 0.454 = 29.51 kilograms.