Cups to grams: why the ingredient matters
Learn why cups cannot convert directly to grams without density, distinguish US and metric cups, and calculate a sample ingredient mass.
Updated · How we checkCups measure volume and grams measure mass. The connection is ingredient density.
Identify the cup definition
This site's cooking calculator uses the US customary cup of 236.5882365 mL. Recipes may instead specify a 240 mL or 250 mL cup. Confirm the recipe convention before applying a conversion; a different cup volume changes the result.
Supply the ingredient density
Mass in grams = volume in milliliters × density in grams per milliliter. The reverse calculation divides mass by positive density. Water, oil and flour do not share one universal density. Packing, moisture and temperature can change measurements, so use a suitable measured or sourced value.
Distinguish mass and fluid ounces
An avoirdupois ounce is a unit of mass. A US fluid ounce is a unit of volume. Converting within one family requires a unit factor; converting between mass and volume requires density as well. For recipes where packing varies, weighing the ingredient can avoid a volume estimate.
Put the formula into practice
Volume: 100 mL. Illustrative density: 0.5 g/mL.
The sample mass is 50 grams. The density is an example, not a recommended value for a specific ingredient.
References
Definitions and method references. Example rates and prices on this page are editable assumptions.