What is a Cup?

The US cup equals exactly 240 milliliters (a definition standardized for nutrition labeling; the legal volume for cooking is 236.588 mL, derived from 8 US fluid ounces). The cup is the cornerstone of American baking and home cooking, with virtually every US recipe using volume measurements rather than the weight measurements common in European cooking. Standard measuring-cup sets include 1, ½, ⅓, and ¼ cup sizes. The metric cup (used in Australia, New Zealand, and increasingly in international recipes) is exactly 250 mL — slightly larger than the US cup. The cup relates to the gallon (16 cups = 1 gal), the pint (2 cups = 1 pt), the fluid ounce (8 fl oz = 1 cup), the tablespoon (16 tbsp = 1 cup), and the milliliter (1 cup ≈ 237–240 mL). American baking-by-volume is sometimes criticized internationally for its variability compared to gram-based measurements.

Visual reference for how the cup relates to other volume units. Each row links to the full converter for that pair.

See all 15 volume units in matrix view →

• US cooking and baking recipes
• Cereal and beverage serving sizes in US nutrition labels
• Volume estimation when no scale is available

• ✓US cup = 240 ml common; 236.6 ml legal; UK cup = 284 ml; metric cup (AU/NZ) = 250 ml.
• ✓Weights (grams) are more reliable than cups — a cup of flour can vary 30% depending on how packed.
• ✓For baking, always use the recipe author's country convention.

• ✗Using a UK 284 ml cup for a US recipe calling for 240 ml — 18% overshoot.
• ✗Treating all dry ingredients as 1 cup = 240 g — only true for water.
• ✗Using a coffee mug as a "cup" — mugs vary 200–400 ml.