What Is a Gram? What Is a Cup?
What Is a Gram? What Is a Cup?
A gram and a cup measure two different things. A gram measures weight, or more precisely mass. A cup measures volume, the space something takes up. That single difference is why converting between them always depends on the ingredient: a cup of feathers and a cup of stones weigh very different amounts, and the same is true in the kitchen for oats and honey.
What is a gram?
A gram is a metric unit of mass. One thousand grams make one kilogram, and one gram is roughly the weight of a small paperclip. The metric system was built around tens, which is why grams convert cleanly to kilograms and milligrams, and why most of the world weighs ingredients in grams. Kitchen scales read in grams because grams are small enough to be precise: the difference between 120 and 150 grams of flour matters in a cake, and grams capture it.
What is a cup?
A cup is a unit of volume from the US customary system, the system American recipes still use. One US cup holds 240 milliliters, which equals 16 tablespoons or 48 teaspoons. Cups were designed for speed: scooping flour or pouring milk is faster than weighing, and for most of cooking history that speed mattered more than precision. The trade-off is accuracy, because a cup of flour can weigh anywhere from 120 to 150 grams depending on how it is packed.
Cup sizes are not the same everywhere
| Cup type | Volume | Used in |
|---|---|---|
| US customary cup | 240 ml | United States recipes |
| Metric cup | 250 ml | Australia, New Zealand, metric recipes |
| UK imperial cup | 284 ml | Older British recipes |
This site uses US cups throughout, because most online recipes that list cups are American. If your measuring cups are metric, your amounts will run about 4 percent higher than the US values here. For baking, that difference is worth correcting. For soups and salads, it is not.
Why recipes use both
American recipes use cups because the US never fully adopted the metric system for cooking, while professional bakers and most of the rest of the world use grams because weighing is more accurate and scales cleanly. A recipe doubled in cups doubles the measuring error too, while a recipe doubled in grams stays exact. That is why serious baking books give weights first and cups second, if they give cups at all.
Which should you use?
Use grams for baking, for flour and salt, and whenever a recipe gives you grams in the first place. Use cups when the recipe gives cups and the dish is forgiving, like a soup or a salad dressing. When you need to switch, use the Grams to Cups Converter, and read How to Convert Grams to Cups for measuring technique that keeps the conversion honest.