Volume Converter

How do you convert volume units?

The simplest way to handle any volume conversion is to convert the value into liters first, then from liters into the unit you want. Every unit here has a fixed size in liters, so the same two steps work for spoons, bottles, tanks and shipping containers.

The two-step method

1. Multiply the value by the size of the starting unit in liters.
2. Divide the result by the size of the target unit in liters.

For example, to convert 5 US gallons to liters: 5 × 3.785411784 = 18.93 L (18.92705892 L exactly). To turn 2 liters into US cups: 2 ÷ 0.2365882365 = 8.45 cups. The liters to gallons converter and the mL to cups converter do the arithmetic for any amount, and the gallons to liters converter and the cups to mL converter run the other way.

Volume and cubic length units

Volume is length cubed, so cubic units scale by the cube of the length factor. A cubic meter is 10 × 10 × 10 = 1,000 liters because a liter is a cube 10 cm on each side. One cubic centimeter (cc) is exactly one milliliter, which is why engine sizes and syringes use the two interchangeably. On the customary side, the US gallon is defined as exactly 231 cubic inches, and a cubic foot holds about 7.48052 US gallons.

What is the SI unit of volume, and how is the liter defined?

The cubic meter (m³) is the SI unit of volume, and the liter is exactly one cubic decimeter, 0.001 m³, a unit the BIPM SI Brochure accepts for use with the SI. A cube 10 cm on each side holds one liter, a cube 1 m on each side holds 1,000 liters, and a cube 1 cm on each side holds one milliliter, which is why 1 mL and 1 cm³ (1 cc) are the same volume.

The liter was once defined as the volume of one kilogram of water at its densest, which made it slightly larger than a cubic decimeter. In 1964 the General Conference on Weights and Measures fixed it at exactly 1 dm³, and in 1979 it allowed the capital L as a symbol alongside the lowercase l, to avoid confusion with the digit 1.

Customary units are tied to the same base through length. The US gallon is defined as exactly 231 cubic inches, and because the inch is exactly 2.54 cm, that is exactly 3.785411784 L, as NIST Handbook 44 lists. The imperial gallon was redefined in the UK as exactly 4.54609 L. The length converter uses the same inch, and the mL to liters converter covers the most common metric step, dividing by 1,000.

How many cups, pints and quarts are in a gallon?

One US gallon holds exactly 4 quarts, 8 pints, 16 cups or 128 fluid ounces. A gallon splits into 4 quarts; after that each step halves, from quart to pint to cup, and the cup then splits into 8 fluid ounces, 16 tablespoons or 48 teaspoons. Every milliliter value below is exact.

The imperial ladder has the same names but different sizes: 1 imperial gallon is 8 imperial pints or 160 imperial fluid ounces of 28.4130625 mL each. An imperial pint is therefore 20 imperial fluid ounces, while a US pint is 16 US fluid ounces.

Fluid ounces are not ounces

A fluid ounce measures volume and an ounce measures weight, so the two only line up for liquids with the density of water. One US fluid ounce of water weighs about 1.04 oz, close enough for drinks, but a fluid ounce of honey or oil does not weigh an ounce. For weights, use the grams to ounces converter or the weight converter.

How big is a cup, and why do recipe measures differ?

A US cup is exactly 236.5882365 mL, half a US pint, while a metric cup is 250 mL, and recipes are where these differences cause the most mix-ups. Australia, New Zealand, Canada and South Africa commonly use the metric cup, about 5.7% more; the mL to cups converter uses the US cup. US nutrition labels use yet another figure, a rounded 240 mL cup, so a label serving and a measuring cup can differ slightly.

Spoons follow the same pattern. The US tablespoon is 3 teaspoons, or about 14.79 mL, and 16 tablespoons make one US cup. Metric spoons are usually rounded to 5 mL and 15 mL, while Australian tablespoons are 20 mL. For small amounts the differences hardly matter, but they add up in baking, where many cooks prefer to weigh ingredients instead. The tablespoons to cups converter helps scale US recipes, and the cooking converter turns cups of a given ingredient into grams.

Bottles, cans and cartons

A 12 US fl oz soda can holds about 354.88 mL, and a 500 mL water bottle is about 16.9 US fl oz. A 2-liter bottle is roughly 67.6 US fl oz, or just over half a US gallon.

Where is each volume unit used?

Liters and milliliters are the everyday volume units almost everywhere, while the United States uses gallons, quarts, cups and fluid ounces, and the UK keeps the imperial pint for beer and milk. Industry adds cubic meters, cubic feet and cubic inches for bulk and engineering work.

• Milliliters and liters: drinks, food packaging, medicine, fuel and engine capacity in nearly every country, and on most US bottles alongside fluid ounces.
• Cubic meters: water and gas meters, concrete and earthworks, shipping volume and room ventilation.
• US gallons, quarts and pints: fuel at the pump, milk, paint and beverages in the United States.
• Imperial gallons and pints: beer and cider served by the pint in the UK and Ireland, and fuel economy figures quoted in miles per imperial gallon.
• Cups, tablespoons and teaspoons: home cooking, especially in US recipes.
• Fluid ounces: drink sizes, cosmetics and bottled liquids in the US.
• Cubic feet and cubic inches: refrigerator and freezer capacity, luggage and storage, natural gas billing and engine displacement in the US.

If you are comparing fuel costs or efficiency between countries, the fuel converter handles mpg and L/100 km with the correct gallon.