Volume Converter

Volume conversion goes wrong more often than almost any other unit. US gallons and UK gallons differ by 20%. US cups and metric cups differ by 6%. US fluid ounces are slightly different from UK fluid ounces, and both are different from ounces of weight. The calculator below normalizes through liters so none of that matters for the arithmetic, but it will still matter if you pick the wrong unit in the dropdown.

The US gallon is 3.785 liters (defined as 231 cubic inches, a 1707 English wine-gallon standard that the Americans kept after independence). The UK imperial gallon is 4.546 liters, defined in 1824 as the volume of 10 pounds of water at 62°F. That is why a US gallon of gas and a UK gallon of petrol are different amounts. A US miles-per-gallon of 30 is about 25 UK MPG — review sites that quote MPG without specifying which country are unreliable.

The cubic meter is the SI volume unit; the liter (1/1000 m³) is more human-scaled and has been the metric working unit since 1793. The liter was briefly redefined in 1901 (as the volume of 1 kg of water), re-redefined in 1964 (back to 1/1000 m³), and has been unambiguous ever since.

US gallons to liters: multiply by 3.785. Liters to US gallons: divide by 3.785 or multiply by 0.2642. Fluid ounces to milliliters: multiply by 29.574. UK to US: a UK pint is 568 ml, a US pint is 473 ml — the UK pint is 20% bigger. A pint of beer in London is a real pint; a 'pint' in Manhattan is often a 16-oz cheater glass (473 ml or less).

Cubic units have cubed conversion factors. 1 inch = 2.54 cm, so 1 in³ = 16.387 cm³, not 2.54 cm³. A 100 in³ engine is 1.639 liters. A 350 cubic-inch V8 (5.7 L) is where the old '350' comes from — cubic inches, not horsepower or any other number.

• Liters
• Milliliters
• Cubic Meters
• US Gallons
• UK Gallons
• US Quarts
• US Pints
• US Fluid Ounces
• US Cups

• US vs UK gallon. Always check the country of the spec sheet. A UK gallon of fuel is 20% more than a US gallon.
• Fluid ounces vs ounces of weight. 8 fluid ounces of water happens to weigh about 8 ounces (because water density is close to 1 g/ml), but 8 fluid ounces of honey weighs about 12 ounces and 8 fluid ounces of whipped cream weighs about 2. Cooking recipes by fluid ounces become dangerous at weight-sensitive steps.
• Teaspoon and tablespoon standards. US tsp is 4.93 ml; metric tsp is 5 ml; Australian tbsp is 20 ml (not 15 ml). Tight baking recipes care about this.
• Cubic conversion exponents. A 10× linear increase is a 1000× volume increase. A cube that's 'twice as big' has 8× the volume. Landscape and hot-water-tank estimates break from people forgetting this.
• Dry vs. liquid measure (US only). A US dry pint is 550.6 ml; a US liquid pint is 473.2 ml. Almost nobody uses dry pints anymore, but USDA produce reports still do — '1 pint of blueberries' at the farmers market is the dry pint.

• Espresso shot: 30 ml (1 fl oz).
• Standard wine bottle: 750 ml (25.4 fl oz).
• US cup of water: 236.6 ml, weighs 236.6 g.
• 1-gallon US milk jug: 3.785 L (128 fl oz), weighs about 3.9 kg.
• Car gas tank, US average: 50-65 L (13-17 US gal).
• Bathtub, standard soaker: 150-180 L (40-48 US gal) when filled for a bath.
• Olympic swimming pool: 2.5 million liters (660,000 US gal).
• 5-gallon water cooler jug: 18.93 L, weighs 18.9 kg — heavier than a checked bag.

• If a recipe is imported, check the country. UK cookbooks assume imperial cups and metric cups interchangeably; US cookbooks assume US cups.
• Measure viscous ingredients by weight. Honey, syrup, and peanut butter cling to measuring cups; a kitchen scale avoids the mess and the error.
• For concrete and landscaping, always convert to cubic meters or cubic yards at the start. A cubic yard is 0.7646 m³; a cubic meter is 1.308 cubic yards. Getting this wrong orders the wrong amount of material.

Related: Cooking Volume Converter · Flow Rate Converter · Density Converter.