Volume Converter

Volume measures three-dimensional capacity. The SI unit is the cubic meter, but practical work uses liters (1 L = 0.001 m³) and milliliters. US customary units add gallons, fluid ounces, cups, tablespoons, and teaspoons — all defined by separate legal acts.

This converter handles seven common volume units bidirectionally. US and imperial gallons are explicitly distinguished — they differ by about 20%.

The US gallon is defined as exactly 231 cubic inches (3.785411784 liters), inherited from the British wine gallon of 1707 and never updated. The imperial gallon, defined in the UK Weights and Measures Act of 1824, equals 4.54609 liters — the volume of 10 pounds of water at 62°F. The two diverged when the US kept the older wine gallon while Britain redefined. Within each system, units chain consistently: 1 US gallon = 4 quarts = 8 pints = 16 cups = 128 fl oz = 256 tablespoons = 768 teaspoons. The imperial system has 8 imperial pints per gallon and 20 imperial fluid ounces per pint, breaking the parallel with US.

A worked example: a recipe calling for 2 cups of milk. In the US, 2 cups = 473.18 mL. The same recipe in a UK source pre-metrication would mean 2 imperial cups = 568 mL — a 20% larger amount. A bottle labeled 750 mL is 25.36 US fl oz or 26.40 imperial fl oz. Gas pump fills in liters versus US gallons: 50 L = 13.21 US gallons; 50 L = 11.00 imperial gallons. The numerical similarity for liters and quarts (1 L ≈ 1.057 quarts) is a coincidence that helps approximate but doesn't replace conversion.

Limitations: volume conversion is exact, but volume-to-weight requires substance density and is not what this tool does. "How many grams in a cup of flour" depends on whether you scoop, sift, or weigh. Dry measure cups (used in US baking) and liquid measure cups have the same nominal volume but different scoop shapes; 1 dry cup of flour by volume varies 100–150 g depending on packing, which is why professional baking weighs ingredients. The converter assumes liquid measure throughout.