Volume Converter

What this converter answers

Given an amount from a recipe, a label or a container, it tells you what that comes to in the unit you need and whether the figure is exact. Enter one amount and milliliters, liters, cups, spoons, fluid ounces, pints, quarts, gallons and cubic units all fill in at once. US and UK imperial units that share a name are kept apart and labeled, and when a unit comes in several sizes (a cup, a pint, a gallon) the page shows your amount in each of them, so a recipe or container from another country reads correctly.

How to use it

• Volume: the amount, in the unit under From. Kitchen fractions work as typed: 3/4, 2 1/2, 1-1/2 or 2½, as well as 1,250 and 3e-6. On a phone, the keys under the box type the fraction bar and a space.
• From and To: the unit in your recipe or on the label and the unit you will measure with. The lists run metric, US cups and spoons, US liquid, US dry, UK imperial, then cubic units. Cups and spoons show their size in mL, because four different cups are in use.
• Significant figures: Auto shows up to 12 significant figures, so exact values such as 3.785411784 appear complete. Choose fewer for a shorter answer.
• Density (optional): in grams per milliliter (the same number as kilograms per liter); water is about 1. Leave it blank for a pure volume conversion; enter one to see an estimated weight.

The Try buttons load a US gallon of water (in liters, with its weight at 1 g/mL), a UK pint in US pints, 500 mL in cups and a cubic foot in gallons, each worked through below.

How many mL are in a cup?

It depends on the cup. A US recipe’s cup is 236.5882365 mL, US nutrition labels use 240 mL, a metric cup is 250 mL, and an imperial cup is half a UK pint, 284.130625 mL:

The label cup is 1.4% larger than the US cup and the metric cup 5.7% larger; the imperial cup is 20.1% larger. When you choose a cup under From or To, the result lists the same amount in all four, so you can see how much the choice matters.

Common US cup measures in milliliters (5 significant figures):

Going the other way, 100 mL is 0.42268 US cups, 250 mL is 1.0567 and 500 mL is 2.1134.

Volume conversion formula

Every unit has a fixed size $s$, here in milliliters. To convert an amount $V$ from one unit to another:

$$V_{\text{to}} = V_{\text{from}} \times \frac{s_{\text{from}}}{s_{\text{to}}}$$

• $V_{\text{from}}$ is the amount you have and $V_{\text{to}}$ the amount in the new unit.
• $s_{\text{from}}$ and $s_{\text{to}}$ are the sizes of one of each unit: 3,785.411784 mL for a US gallon, 4,546.09 mL for an imperial gallon, 1,000 mL for a liter.

US units all come from the inch: the US gallon is defined as 231 cubic inches, and since 1 in = 2.54 cm exactly, 1 in³ = 16.387064 mL and the gallon is exactly 3,785.411784 mL. The quart, pint, cup, fluid ounce, tablespoon and teaspoon are 1/4, 1/8, 1/16, 1/128, 1/256 and 1/768 of it. UK imperial units come from the gallon of exactly 4.54609 L. Both systems are therefore exact in milliliters, which is why the converter can mark results Exact; most reverse factors, such as 1 L ≈ 0.264172 US gal, never end.

Worked example: 2 1/2 US cups in milliliters

A US recipe asks for 2 1/2 cups of stock and your measuring jug is marked in milliliters.

1. The size of the cup: 1 US cup is 1/16 of a US gallon, and 3,785.411784 mL ÷ 16 = 236.5882365 mL.
2. The fraction: 2 1/2 = 2.5.
3. The conversion: 2.5 × 236.5882365 = 591.47059125 mL, exactly. On a measuring cup marked every 10 mL, that is just above the 590 mL line.
4. If the recipe had meant another cup, the same 2 1/2 cups would be 600 mL (nutrition-label cup), 625 mL (metric cup) or 710.3265625 mL (imperial cup). The imperial reading is 20.1% more liquid than the US one.

The conversion table under the result also gives this amount as 20 US fl oz, 40 US tablespoons, 1.25 US pints and 1.04084273079 imperial pints.

Is a UK pint bigger than a US pint?

Yes. A UK imperial pint is 568.26125 mL and a US liquid pint is 473.176473 mL, so the imperial pint is about 20% larger: 1 imperial pint = 1.20095 US pints, and 1 US pint = 0.832674 imperial pints. The same 20.1% gap applies to quarts and gallons, because both systems divide their gallon the same way. The fluid ounce goes the other way, because an imperial pint holds 20 imperial fluid ounces while a US pint holds 16 US fluid ounces:

When From and To share a name, such as a US pint and an imperial pint, the page says so above the result and gives the size difference. A US dry pint (550.6104713575 mL), used for dry goods, is a third kind of pint.

Tablespoons and teaspoons in mL

A US tablespoon is half a US fluid ounce, 14.78676478125 mL, and a US teaspoon is a third of that, 4.92892159375 mL. Metric spoons are 15 mL and 5 mL, and US nutrition labels use the same 15 mL and 5 mL. The difference is 1.4%.

A US cup is 16 tablespoons and a tablespoon is 3 teaspoons, so 1/3 cup is exactly 5 1/3 tablespoons, or 16 teaspoons.

Liters to gallons and gallons to liters

Multiply US gallons by 3.785411784 to get liters, or imperial gallons by 4.54609. Both factors are exact. Going from liters, divide by the same numbers:

A price per gallon converts the other way round from the volume. At, for example, $3.50 per US gallon, one liter costs $3.50 ÷ 3.785411784 = $0.924602. Multiplying instead gives $13.25, the price of a gallon’s worth of liters bought at $3.50 each.

Cubic feet, cubic yards and gallons

A cubic foot is 12 × 12 × 12 = 1,728 cubic inches, and a US gallon is 231 cubic inches, so 1 ft³ = 1,728 ÷ 231 = 7.48051948052 US gallons (28.316846592 L). A cubic yard is 27 cubic feet: 201.974025974 US gallons or 764.554857984 L. A cubic meter is 264.172052358 US gallons, 35.3146667215 ft³ or 1.30795061931 yd³.

For example, a raised bed 8 ft long, 4 ft wide and 1 ft deep holds 8 × 4 × 1 = 32 ft³ of soil, which is 1.18518518519 yd³ or 239.376623377 US gallons. Enter 32 with From set to cubic feet to see it in every unit. To find the volume of a round or sloped shape first, use a volume calculator for that shape, then convert the result here.

Can you convert cups to grams?

Not without the density of what is in the cup. A cup measures volume, and a cup of water, oil or flour holds the same volume but weighs different amounts. The weight is the volume times the density:

$$\text{weight (g)} = \text{volume (mL)} \times \text{density (g/mL)}$$

Water is roughly 1 g/mL, a little less when warm: 0.99802 g/mL at 70 °F (21 °C). At 1 g/mL a US gallon of water weighs 3,785.411784 g, which is 8.34540445202 lb; at 0.99802 g/mL it is 3,777.91666867 g, or 8.3288805512 lb. NIST Handbook 44 describes the imperial gallon as the volume of 10 pounds of water under specified conditions; at 1 g/mL its 4,546.09 g weigh 10.022412855 lb.

For foods, a US nutrition label gives the density indirectly, because each serving is listed both in household measures and in grams. If a label says 1/4 cup (30 g), that is 30 g in 60 mL (a quarter of the 240 mL label cup), or 0.5 g/mL. Enter that under Density and the converter estimates the weight of any volume of it, with pounds and ounces by weight alongside. It never assumes water for you.

Reading the result

• The headline is the amount in the To unit, then the equation and whether it is exact or how it was rounded.
• The factor line reads both ways for the units chosen: 1 US cup = 236.5882365 mL exactly, while 1 mL ≈ 0.00422675283773 US cup is rounded and marked ≈.
• ”… isn’t one size” appears when a cup, spoon, fluid ounce, pint, quart or gallon is involved, and lists your amount in every kind of that unit. When From and To are two kinds of the same unit, the warning below takes its place.
• “Same name, different size” is a warning that From and To share a name but not a size, with the percentage between them.
• Weight tiles (with a density) show the estimated weight, the same in pounds and ounces, and what one From unit weighs.
• How this was calculated shows the conversion with your numbers and the definition of each unit, back to the inch or the liter.
• The conversion table lists the amount in every common unit, grouped and marked Exact or Rounded. Select a unit name, such as tablespoons, to make that the headline answer; Download CSV and Copy table take all of the rows.
• Each kind of cup (or pint, gallon …) tables give the size of every kind in mL, your amount in it and the difference from the one you chose.
• Save for comparison keeps up to three conversions side by side and shows the change in liters from the first.

Common volume conversion mistakes

• Using a UK recipe’s pint as a US pint. The US pint is 16.7% smaller, so measuring a UK recipe’s pint of milk with a US pint gives about a sixth too little. The same holds for quarts and gallons.
• Reading fluid ounces as ounces of weight. A fluid ounce is a volume. 8 US fl oz of water weighs about 8.35 oz at 1 g/mL, and anything denser weighs more; convert with a density.
• Mixing the fluid ounces. A UK recipe’s 10 fl oz is 284.130625 mL, but 10 US fl oz is 295.735295625 mL, 4.1% more.
• Rounding the gallon to 4 liters. It overstates every liter figure by 5.7%; 3.8 L is still 0.39% high. Use 3.785411784, or let the converter do it.
• Multiplying a price per gallon by 3.785 to get a price per liter. Prices divide: a lower price for the smaller unit.
• Confusing cubic feet and cubic yards. A cubic yard is 27 cubic feet, not 3.

Assumptions and limitations

• The factors are the exact definitions above, and results are rounded only for display, to the significant figures you choose. A fraction typed as 1/3 is exactly one third, so 1/3 US cup comes out as exactly 78.8627455 mL.
• A converted value can’t be more precise than the measurement behind it: the converter can’t tell a level spoonful from a heaped one.
• The metric cup (250 mL) and the imperial cup (half an imperial pint) are kitchen measures defined by those volumes; UK law defines the pint and gallon but no cup.
• The weight estimate is only as good as the density you enter, and density changes with temperature.
• Volumes must be 0 or more and at most 10¹⁵ in the unit typed. Units not in the lists can go through one that is: an oil barrel, for instance, is 42 US gallons.