When purchasing food items, such as fruit or vegetables, you buy them by the pound in the United States. However, when you go to countries that use kilograms instead of pounds, knowing the conversion rate helps you know how much to purchase to get the same amount regardless of measurement scale. Knowing the cost per kilogram, instead of per pound, also helps you calculate how expensive it will be to use a recipe that doesn't use pounds.

Multiply the number of pounds in your measurement by .454, which is how many pounds are in 1 kilogram. For example, assume 3 pounds of peaches costs $2.64. Three pounds is equal to 1.36 kg.

Divide the total cost by the number of pounds to determine the cost of each pound. For the previous example, $2.64 divided by three is equal to 88 cents per pound.

Divide the original cost, $2.64, by 1.36 kg to get the price in kilograms, which is $1.94 per kilogram. Therefore, 88 cents per pound is equal to $1.94 per kilogram. You can alternatively multiply the per-pound rate, 88 cents, by 2.2, the number of pounds in one kilogram, to get approximately the same answer.