Volume Converter

How do I convert litres to gallons, cups and fluid ounces?

Use this free online volume converter: enter a number, pick the unit you have and the unit you want, then press the Convert button. It covers litres, millilitres, cubic metres, US gallons, US quarts, US pints, US cups, US fluid ounces, US tablespoons, US teaspoons and UK gallons, and shows the result with up to six decimal places.

What does the volume converter do and why is it useful?

Volume units are famously confusing. A recipe from an American site asks for cups and fluid ounces, a European one uses millilitres and litres, a fuel receipt may be in UK gallons, and a swimming pool or water tank is described in cubic metres. On top of that, a US gallon and a UK gallon are not the same size, which catches out many travellers and online shoppers.

This tool puts eleven volume units in one place. You enter one number, pick two units, press the button and read the answer. It is useful for cooking, car fuel economy comparisons, aquariums, gardening, and school or work tasks. For related measurements you can use the weight converter, since ingredients are often listed by weight in one country and by volume in another.

How does the converter work under the hood?

All conversions run through a single base unit, the litre. The value you enter is multiplied by the number of litres in the source unit, and that figure is divided by the number of litres in the target unit. Every unit can therefore be paired with every other unit using the same logic.

The anchor values are:

• 1 US gallon = 3.785411784 litres, an exact definition.
• 1 UK gallon = 4.54609 litres, also exact.
• 1 cubic metre = 1000 litres, and 1 litre = 1000 millilitres.

The smaller US units are fractions of the US gallon: a quart is one quarter, a pint one eighth, a cup one sixteenth, a fluid ounce one 128th, a tablespoon one 256th and a teaspoon one 768th. Results are rounded to at most six decimal places. The tool never updates as you type. The calculation runs when you press Convert and not before.

How do I use the volume converter step by step?

1. Type the amount you want to convert in the value field.
2. Choose the starting unit from the first drop-down list.
3. Choose the target unit from the second drop-down list.
4. Press the Convert button.
5. Read the converted amount on the page. To try other numbers or units, change the fields and press Convert again.

What do real conversions look like? Worked examples

These figures were computed from the exact definitions above.

Example 1: 1 US gallon to litres

Input: 1, from US gallons, to litres. Result: 3.785412 L (the exact value is 3.785411784).

Example 2: 2 litres to US cups

Input: 2, from litres, to US cups. Calculation: 2 / (3.785411784 / 16). Result: 8.453506 cups.

Example 3: 330 millilitres to US fluid ounces

Input: 330, from millilitres, to US fluid ounces. Calculation: 0.33 L divided by (3.785411784 / 128). Result: 11.158627 fl oz. This is the size of a standard drink can in many countries.

Example 4: 1 UK gallon to US gallons

Input: 1, from UK gallons, to US gallons. Calculation: 4.54609 / 3.785411784. Result: 1.20095 US gal. Going the other way, 1 US gallon is 0.832674 UK gallons.

Example 5: 10 UK gallons to litres

Input: 10, from UK gallons, to litres. Calculation: 10 x 4.54609. Result: 45.4609 L.

Example 6: 3 US tablespoons to US teaspoons

Input: 3, from US tablespoons, to US teaspoons. Calculation: 3 x 3. Result: 9 tsp. As a bonus, 1 US gallon converts to exactly 16 cups.

How do the units compare at a glance?

Unit	Share of a US gallon	Approx. litres
US gallon	1	3.785412
US quart	1/4	0.946353
US pint	1/8	0.473176
US cup	1/16	0.236588
US fluid ounce	1/128	0.029574
US tablespoon	1/256	0.014787
US teaspoon	1/768	0.004929

A litre is a bit more than a US quart, and a US gallon is a bit less than four litres. A UK gallon is about 20 percent larger than a US gallon.

How can I use volume conversions in practice?

Cooking is the classic case. A recipe that calls for 2 litres of stock needs about 8.453506 US cups, so you can measure it with a standard cup set and a rounded figure of 8.5 cups is close enough for soup. A 330 millilitre drink is about 11.158627 US fluid ounces, which helps when comparing labels between countries.

Fuel is another. A tank of 10 UK gallons holds 45.4609 litres, while a tank of 10 US gallons holds 37.85411784 litres. The difference is large enough to distort any fuel economy comparison, which is why the gallon type matters so much. Converting both tanks to litres first puts them on the same footing.

Water storage and gardening follow the same pattern. A barrel measured in cubic metres can be turned into litres, then into gallons, by running the conversion in two button presses or in one by choosing the final unit directly. Choosing the final unit directly is better, because it avoids stacking rounded intermediate values.

Whichever task you have, write the unit beside every number. A figure without a unit is the most common source of recipe disasters and ordering errors, and it takes only a moment to avoid.

What tips help me get accurate results?

• For container dimensions, find lengths first with the length unit converter, then multiply to get a volume.
• Always check whether a source means a US or a UK gallon. The two differ by about 20 percent.
• For baking, convert the full quantity once instead of adding up small rounded conversions.
• Remember that 1 litre equals 1000 millilitres and 1 cubic metre equals 1000 litres. This chain handles most metric needs without a tool.
• Round only the final figure, and use sensible precision: two decimals for fuel, nearest millilitre for cooking.
• If a recipe needs scaling by a ratio, find the scale with the percentage calculator before converting.

What common mistakes should I avoid?

• Mixing US and UK units. The tool offers US cups, pints, quarts and fluid ounces, and UK gallons. Only the gallon exists in both systems here, so choose carefully.
• Confusing fluid ounces with ounces of weight. A fluid ounce measures volume. Use the weight converter for mass.
• Assuming a cup is always 250 millilitres. The US cup in this tool is about 236.59 millilitres, one sixteenth of a US gallon.
• Swapping the two units. Check both lists before you press Convert.
• Expecting live updates. A new result appears only after you press the button.

Who uses a volume converter?

Home cooks and bakers translate recipes between cups and millilitres. Drivers and fleet managers compare fuel prices and consumption across US and UK gallons. Aquarium keepers and gardeners size tanks and watering plans. Students work through chemistry and physics questions, shop owners label products for several markets, and DIY builders convert cubic metres of concrete or water into litres.

Is my data private?

Yes. The conversion runs entirely in your browser, so your numbers are never uploaded, saved or logged. There is no account and no history, and refreshing the page clears the form.

What are the limitations of this tool?

• It supports eleven units. UK pints, imperial fluid ounces, cubic feet, cubic inches and dry measures are not included.
• Results show up to six decimal places.
• It converts one value at a time, with no batch mode, copy button or downloads.
• It does not work out the volume of a shape. Multiply dimensions yourself, then enter the result.

Frequently asked questions

How many litres are in a US gallon?

3.785411784 litres, shown as 3.785412 in results.

How many litres are in a UK gallon?

Exactly 4.54609 litres.

How many cups are in a gallon?

Sixteen US cups make one US gallon.

How many teaspoons are in a tablespoon?

Three. A US tablespoon equals three US teaspoons.

How many US gallons are in 5 litres?

About 1.32086 US gallons.

Why is the UK gallon bigger?

The two countries defined their gallons differently, so the UK unit is 4.54609 litres and the US unit is 3.785411784 litres.

How many cubic metres is 1000 litres?

One cubic metre.

Is a fluid ounce the same as an ounce?

No. A fluid ounce is a unit of volume, while an ounce is a unit of weight. The two only coincide roughly for water, so do not swap them for other ingredients.

How many millilitres are in a US teaspoon?

About 4.93 millilitres, since a teaspoon is one 768th of a US gallon.

Where can I find more utilities?

See the full list of free tools.

Measure liquids the same way everywhere

Enter a quantity, select two units, press Convert, and the answer is there. With exact gallon definitions behind the maths, you can move between litres, cups, fluid ounces and gallons without second-guessing the figures.