How Do You Convert Ounces and Pounds to Grams?

The weight conversions in recipes from other countries are easier than volume conversions, because ounces and pounds are defined constants that do not vary by ingredient. One ounce equals 28.35 grams. Since one pound is 16 ounces, it equals 453.6 grams. Once you memorize these two figures, everything else can be worked out by multiplication and division. As with volume units, there is no difference between countries: these two units represent the same weight in British and American recipes. So if a recipe gives ounces instead of grams, that is actually good news.

In the kitchen, these constants can easily be rounded. It is enough to use 28 grams for an ounce and 454 grams for a pound; for an 8-ounce measure, the rounding difference does not exceed 3 grams, and no recipe can detect it. Keep the decimal precision only for ingredients used in small amounts, such as leaveners, salt, and spices, because a few grams can change the result there. A practical check is to multiply the number of ounces by 30 and subtract a little to get an approximate gram equivalent; you can do this in your head. Once you calculate it and write it in the margin of the recipe, you do not have to repeat the calculation.

The values that appear most often in recipes are not whole pounds but fractions of a pound. A quarter pound is 113 grams, half a pound is 227 grams, and three-quarters of a pound is 340 grams. These three values cover most international recipes, because meat, butter, cheese, and chocolate are sold in these fractions and recipes are written to match the packages. A recipe calling for 1 pound of ground meat needs 454 grams of ground meat; half a pound of butter is 227 grams. If you remember these three values, most conversions require no calculation.

Converting in the other direction is just as easy. If you have grams and need to read a recipe in pounds, divide the number of grams by 454. 500 grams of ground meat is about 1.1 pounds; one kilogram is about 2.2 pounds. This last conversion is especially useful, because you can convert kilograms to pounds by multiplying by 2 and adding a little. If a recipe gives an ingredient in both ounces and pounds, convert both to the same unit and add them together to avoid confusion while reading the list. When units are mixed, converting the list to a single unit also makes the shopping list easier.

One final caution concerns the unit abbreviation. “Oz” in a recipe does not always mean a weight ounce; there is also a separate unit used for liquids, which measures volume. Weight ounces are measured on a scale, while fluid ounces are measured with a measuring cup, and these two units cannot be converted directly into one another. So when you see “oz,” first check whether the ingredient is solid or liquid. If it is solid, the 28.35-gram rule applies; if it is liquid, a different calculation is needed, and that calculation depends on the ingredient’s density.