There are precisely 28.3495231 grams in one ounce. This number is commonly rounded to 28 for easier conversions. The gram is the base unit of mass or weight in the metric system, and the ounce is a unit of weight in the U.S. customary system.

To convert a measurement in ounces to an approximate number of grams, multiply it by the factor 28. Conversely, to convert a measurement in grams to ounces, divide it by the divisor 28. Although ounces are the preferred measurement in the United States, grams are used by most of the world and in all scientific applications.

Grams are a metric unit of weight, while ounces are a U.S. customary unit of weight. When converting dry ingredients in a recipe, the following equivalents may help: 1/4 cup is 56.7 grams, 1/3 cup is 75.6 grams, 1/2 cup is about 113.4 grams and 1 cup is about 225 grams. One pound is equivalent to about 450 grams. One tablespoon is about 14.3 grams, and 1 teaspoon is 4.76 grams.