Converts between metric and imperial volume units (litres, gallons, cups, m³, oil barrels).
Volume is the most multilingual of the everyday measurements. A French recipe in centiliters, an American recipe in cups, a British recipe in fluid ounces (which differ from US fluid ounces!), an industrial spec in cubic meters, an oil-market quote in barrels, an engineering drawing in cubic feet — they all measure the same thing in incompatible units. Cooks doubling a recipe across the Atlantic, scientists translating between European and American journal conventions, contractors comparing quotes from suppliers using different measuring systems, and DIYers buying paint or fuel from an out-of-region merchant all need a quick, reliable converter that handles the full set of common units in one go. This calculator converts a single input value to all 16 other commonly-used volume units at once, so you can see the entire equivalence table without scrolling.
All conversions go through the SI base unit liter (L), with cubic meters and cubic decimeters as exact synonyms (1 m³ = 1 000 L = 1 000 dm³). Each unit has a fixed conversion factor to liters; the calculator multiplies the input value by the source factor to get liters, then divides by every other factor in turn to produce all output values.
Conversion factors (units per 1 liter, exact except where noted):
The factors trace back to international agreements: 1 inch = 2.54 cm exact (1959), 1 US gallon = 231 in³ exact (1707), 1 imperial gallon = 4.546 09 L exact (1985). The "US fluid ounce" is not the same as the imperial fluid ounce: imp fl oz = 28.413 mL, US fl oz = 29.574 mL. A pint of beer in London is 568 mL; in New York 473 mL. The calculator handles both correctly.
Enter the value in the source unit. Pick the from-unit in the dropdown — 17 choices spanning metric, US customary, imperial, and engineering. The result panel renders all the other units as KPI cards at once, so a single conversion gives you 16 output values to read off.
1 US gallon to everything else:
1 cubic meter:
1 US cup to mL: 236.588 mL — close to but distinctly different from the 250 mL that some EU bakers casually substitute.
US fluid ounce vs imperial fluid ounce. Different by 4.0 %. A 16-oz US pint is 473 mL; a 16-oz imperial half-pint would be 454 mL (but no one calls it that — UK pubs sell 568 mL pints). When a recipe says "16 oz", the country of origin matters.
Imperial vs UK metric units. Modern UK practice mixes imperial volume units (pint, gallon for fuel) with metric in supermarkets. "Pint of milk" sold in UK supermarkets is 568 mL exactly (imperial pint), but the carton may show "0.568 L" rather than the imperial label.
Cup is not a single value. US legal cup (240 mL, used in nutrition labelling), US customary cup (236.588 mL), metric cup (250 mL, used in Australia/NZ), imperial cup (284.131 mL — historical). The calculator uses the US customary cup (236.588 mL) by default. Substituting the wrong cup definition over a 4-cup ingredient list throws scaling off by 5 %.
Tablespoon and teaspoon variation. US tbsp = 14.787 mL, UK tbsp = 15 mL (metric), Australian tbsp = 20 mL. Recipes are often agnostic, but precision baking is not.
Dry vs liquid measure. Imperial measures historically distinguished dry pints/quarts from liquid; US-customary still does for some grain measures (1 dry US pint = 0.551 L vs liquid 0.473 L). The calculator uses liquid measures throughout.
Cubic vs gallon at different scales. Confusion arises at the boundary: 1 m³ ≠ 1 000 imperial gallons (it's about 220). Always compare via L.
Oil barrel ambiguity. The "petroleum barrel" is 42 US gal = 158.987 L; a "beer barrel" or "wine barrel" is different (US beer barrel = 117 L). The calculator uses the petroleum/oil barrel.
Mass vs volume confusion. "1 ounce of butter" is mass (28.35 g); "1 fluid ounce of milk" is volume (29.6 mL). Recipes that conflate the two are ambiguous and need context.
Significant-figures discipline. The conversion factors above are exact or 7-significant-figure; the calculator returns 4–6 decimal places. For trade in cargo volumes, use the legally specified factors and rounding rules.
Temperature dependence. Liquid volumes vary with temperature (water expands ~2 % per 100 °C). Trade and engineering specs reference "at 15 °C" or "at 60 °F"; the calculator is unitless about temperature.
Capacity vs weight in industry. Tank trucks, ships, and pipelines often quote mass and report volume via density at a reference temperature. Density of water = 1 kg/L exactly (definition); other liquids deviate.