Volume & Capacity Unit Converter

Convert between any pair of volume units — liter, milliliter, cubic meter, cubic centimeter, US gallon, UK imperial gallon, quart, pint, cup, fluid ounce, tablespoon, and teaspoon — using conversion factors verified against NIST and BIPM references. Type a value and the result updates instantly.

Reviewed by WuTools Engineering Team · Last updated 2026-05-07

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What is volume, and why are there so many units?

Volume is the amount of three-dimensional space an object occupies. In SI units the coherent unit is the cubic meter (m³), but the more practical unit for everyday liquids is the liter (L) — defined as exactly 0.001 m³ since 1964. One liter is therefore one cubic decimeter, the volume of a 10 cm × 10 cm × 10 cm cube, and the milliliter (mL) is exactly one cubic centimeter (cm³). The liter is technically a non-SI unit "accepted for use with the SI" by the BIPM, which means it is universally legal but the cubic meter remains the formally coherent unit for scientific work.

The reason there are so many volume units is historical, not scientific. The United States kept the colonial-era "queen Anne" gallon as its liquid gallon (3.785411784 L), distinct from both the dry gallon and the British imperial gallon. The United Kingdom adopted a new imperial gallon in 1824 (4.54609 L), now used in Britain, Canada (officially), and a handful of Commonwealth countries. Cooking inherited a separate set — cups, tablespoons, teaspoons — defined differently in the US, the UK, Australia, and continental Europe. Each industry locked in a unit before metrication, and the switching cost is high enough that the old units persist on cookbooks, fuel pumps, beverage cans, and pharmaceutical droppers.

The volume units, explained

Liter (L) and milliliter (mL) — the metric workhorses

One liter equals exactly 0.001 m³ = 1 cubic decimeter. The milliliter (mL) is one-thousandth of a liter, identical to one cubic centimeter (cm³). These two units cover almost every consumer use: bottled drinks (500 mL, 1 L, 1.5 L), engine displacement (a 2.0 L engine is 2000 cm³), IV drip rates (mL per hour), and lab pipettes (microliters and milliliters). Capital L is preferred over lowercase l in many style guides to avoid confusion with the digit 1.

Cubic meter (m³) — the SI coherent unit

The cubic meter is the formal SI unit of volume: 1 m³ = 1000 L. It is the natural unit for civil engineering (concrete pours, room dimensions), gas billing (natural gas and water utilities meter in m³), bulk shipping (container capacity), and HVAC airflow specifications. The cubic decimeter (dm³ = 1 L) and cubic centimeter (cm³ = 1 mL) are the same volumes you reach via the liter, just renamed.

US liquid gallon and its subdivisions — fuel and groceries

1 US liquid gallon = 4 US quarts = 8 US pints = 16 US cups = 128 US fluid ounces = 3.785411784 L exactly. This is the unit at US gas pumps, milk jugs, and motor-oil bottles. Confusingly, the US also has a separate dry gallon (≈ 4.405 L) for grain and produce, which is why "gallon" alone is ambiguous in US usage — fuel and beverages are always the liquid gallon.

UK imperial gallon and its subdivisions — British and Commonwealth

1 UK imperial gallon = 4 imperial quarts = 8 imperial pints = 4.54609 L exactly. The UK gallon is about 20% larger than the US gallon (4.546 vs 3.785 L). UK pints (568 mL) are the legal unit for draught beer in British pubs and for milk doorstep deliveries; US pints (473 mL) are the legal unit for US draught beer and ice cream pints. Numerically equal pints ("a pint") in the two countries are different volumes, a recurring source of recipe errors.

US cup, tablespoon, and teaspoon — cooking measures

Cooking units are defined by US legal volumes for FDA nutrition labels: 1 US legal cup = 240 mL exactly = 8 fl oz; 1 US tablespoon = 14.7867647... mL ≈ 15 mL; 1 US teaspoon = 4.92892159... mL ≈ 5 mL. The traditional "customary cup" used in older US cookbooks is 236.5882365 mL (1/16 US gallon) — a 1.4% difference rarely noticed in practice. Australian, UK, and metric cups differ: an Australian metric cup is 250 mL, a Japanese cup is 200 mL.

Fluid ounce — the same name, three different sizes

The US fluid ounce is 29.5735295625 mL (1/128 US gallon). The UK fluid ounce is 28.4130625 mL (1/160 imperial gallon) — about 4% smaller. The "food-labeling fluid ounce" used for FDA nutrition panels is rounded to exactly 30 mL. A 12 fl oz US soda can holds 354.88 mL; a 250 mL European energy drink holds 8.45 US fl oz. Always check the source country before scaling a recipe.

Real-world applications and which unit to expect

Beverages and bottled drinks: Standard sizes follow the local market: a US soda is 12 fl oz (355 mL) or 20 fl oz (591 mL); a European bottled water is 500 mL or 1.5 L; a wine bottle worldwide is 750 mL; a UK pub pint is 568 mL; a US craft-beer can is 16 fl oz (473 mL); a Japanese sake bottle is 720 mL or 1800 mL (ichigō × 10).
Cooking and baking: US recipes use cups, tablespoons, teaspoons, and fluid ounces. European and Australian recipes use grams (for solids) and milliliters (for liquids). Modern recipes often list both. Critical baking ratios should always be measured by mass when possible — volume measurements of flour vary 20% with how it's scooped.
Fuel and motor oil: US and Liberian gas pumps display gallons (typically tank sizes 12–20 US gal, 45–76 L). Most other countries display liters (typical fill 30–60 L). Aircraft fuel uses both gallons and liters depending on jurisdiction; jet aviation often quotes pounds or kilograms of fuel rather than volume because density varies with temperature.
Engine displacement: Engine size is given in cubic centimeters (cc) for motorcycles and small engines (a 600 cc sport bike), or liters for cars and trucks (a 2.0 L turbo, a 6.6 L diesel V8). Conversion is direct: 1 L = 1000 cc.
Medical and pharmaceutical: Prescriptions and IV drips are dosed in mL or microliters. Insulin syringes are graduated in international units (IU) but typically deliver 1 mL or less. Inhalers measure puffs in micrograms of drug, not volume.
Construction and concrete: Concrete is delivered by the cubic meter (or cubic yard in the US: 1 yd³ ≈ 0.7646 m³). A typical residential slab pour is 5–15 m³. Topsoil, gravel, and mulch follow the same cubic-meter or cubic-yard convention.
Utility billing: Most water and natural-gas utilities meter in m³. US natural gas is sometimes billed in CCF (hundred cubic feet, ≈ 2.83 m³) or therms (heat content). Always confirm the unit on the bill before spreadsheet analysis.

How much is 1 unit of each in liters?

Unit	Value in liters (L)
1 L (Liter)	1 Pa
1 mL (Milliliter)	0.001 Pa
1 m³ (Cubic meter)	1000 Pa
1 cm³ (Cubic centimeter)	0.001 Pa
1 gal (US) (US liquid gallon)	3.785411784 Pa
1 gal (UK) (Imperial gallon (UK))	4.54609 Pa
1 qt (US) (US liquid quart)	0.946352946 Pa
1 pt (US) (US liquid pint)	0.473176473 Pa
1 cup (US) (US legal cup)	0.2365882365 Pa
1 fl oz (US) (US fluid ounce)	0.0295735295625 Pa
1 tbsp (US) (US tablespoon)	0.01478676478125 Pa
1 tsp (US) (US teaspoon)	0.00492892159375 Pa

Frequently asked questions about volume units

How do I convert between any two volume units?

Multiply by the source unit's liter-factor and divide by the target's. Example: convert 5 US gallons to liters → 5 × 3.785411784 ÷ 1 = 18.93 L. The converter above does this in real time.

Are US and UK gallons the same?

No — and the difference is large. 1 US liquid gallon = 3.785411784 L; 1 UK imperial gallon = 4.54609 L. The UK gallon is about 20% bigger. A car spec sheet quoting "30 mpg (UK)" is therefore reporting better fuel economy than "30 mpg (US)". Recipes that say "a quart of cream" mean 0.946 L if American but 1.137 L if British.

Is a cup the same in every country?

No. The US legal cup (used for FDA nutrition labels) is exactly 240 mL. The US customary cup (used in older cookbooks) is 236.5882365 mL. The Australian metric cup is 250 mL. Japan uses a 200 mL cup. UK old recipes use a 284 mL cup but modern UK recipes use the 250 mL metric cup. For accurate baking, weigh ingredients in grams whenever you can.

What is the difference between a fluid ounce and a regular ounce?

An ounce (oz) is a unit of mass (≈ 28.35 g). A fluid ounce (fl oz) is a unit of volume (≈ 29.57 mL in the US, 28.41 mL in the UK). They share the name only because one US fluid ounce of pure water happens to weigh approximately one avoirdupois ounce. For other liquids (like oil or milk) the two are not numerically equal, even in the US system.

How precise are these conversion factors?

All factors are exact by international definition: 1 US gal = 3.785411784 L, 1 UK gal = 4.54609 L, 1 US fl oz = 0.0295735295625 L. The liter itself is exactly 0.001 m³ since 1964. The display rounds to ten significant digits, far more than any consumer measure can resolve.

Why does my engine displacement say 2.0 L when the spec sheet shows 1998 cc?

Engine sizes are often rounded to a marketing-friendly liter. "2.0 L" is the published label for any displacement between roughly 1950 and 2050 cc. The actual swept volume — typically 1995, 1998, or 1999 cc — appears on the official type-approval document. Both numbers describe the same engine.

What does CC mean on motorcycles and small engines?

CC stands for cubic centimeter and equals milliliter. A 600 cc motorcycle engine has 600 mL = 0.6 L of swept cylinder volume. The unit is preferred for small engines because the numbers stay above 1; "0.6 L motorcycle" sounds smaller than "600 cc motorcycle" even though they're the same.

How do I convert a recipe between US and metric?

For liquids: 1 US cup ≈ 237 mL, 1 tbsp ≈ 15 mL, 1 tsp ≈ 5 mL, 1 US fl oz ≈ 30 mL. For solids: weigh whenever possible — flour, sugar, butter, and other dry ingredients vary in volume depending on how they are scooped. A digital kitchen scale costs less than a measuring-cup set and gives consistent results.

Which unit should I use for scientific publication?

ISO 80000-3 and most journals require SI units, so use cubic meters (m³) for large volumes and liters (L) or milliliters (mL) for chemistry and biology. The US gallon and UK imperial gallon appear only when documenting historical instruments or specifically US/UK engineering practice — and even then SI values in parentheses are now expected.