Convert between liters, gallons, cups, milliliters, fluid ounces, pints, and quarts.
Volume conversions are most frequently needed when cooking from recipes that use different measurement systems. American recipes use cups, tablespoons, and teaspoons. Most of the rest of the world uses milliliters and grams. Understanding the relationships between units prevents measurement errors that can ruin a dish.
The most important cooking conversion: 1 US cup = 240 ml. This is the foundation that all other cooking conversions build from. One tablespoon = 15 ml (approximately — exactly 14.787 ml). One teaspoon = 5 ml (approximately — exactly 4.929 ml). These rounded values are used in recipe development and are accurate enough for all cooking purposes.
Baking is more sensitive to volume measurement errors than general cooking. A loosely scooped cup of flour can weigh as little as 120 grams; a packed cup can weigh 160 grams — a 33% difference that meaningfully affects the outcome. Professional bakers measure by weight (grams or ounces) rather than volume for this reason. When precision matters, use a kitchen scale.
The US gallon (3.785 liters) and the UK imperial gallon (4.546 liters) are different units despite sharing a name. The US gallon is about 20% smaller. This creates confusion in fuel efficiency comparisons: a car achieving 40 US mpg achieves approximately 48 UK mpg — not because the car is different, but because of the gallon size difference.
US and UK fluid ounces also differ. 1 US fl oz = 29.574 ml; 1 UK fl oz = 28.413 ml. A US pint (16 fl oz = 473 ml) is smaller than a UK pint (20 fl oz = 568 ml). This is why British pub-goers receive more beer in a "pint" than Americans expect.