Gallons are used for fuel, milk, paint and water tanks. The U.S. liquid gallon is 231 cubic inches (3.785 L); the imperial gallon used in the UK is 4.546 L. The calculator also shows how much that volume of water weighs.
How to use the Gallon Calculator
- Pick the unit you are starting from in the From menu and type your value.
- Pick the unit you want in the To menu. The heading changes to match – for example “US Gallons to Liters Converter”.
- The most common volume units are shown below at the same time, so you can compare them at a glance.
- Type into any result to convert backwards, then use Copy results – the copied text starts with the heading for your chosen units.
Results update as you type. Everything is calculated in your browser.
How it works
Every volume unit is defined by an exact factor relative to the cubic metre (the base unit). The calculator first turns the value you type into cubic metres, then turns that into the unit you picked in the “To” menu and into each of the common units below it. This two-step method means any unit can be converted to any other – 27 units are available in each menu – and you can type into any field, including a result, to work in the other direction. Changing a unit menu keeps the quantity the same and just re-expresses it, and the page heading and copied results follow your choice.
How to convert volume units
- Choose the unit you have in the From menu and type the value, for example 1 US gal.
- Choose the unit you want in the To menu, for example litres. The page heading changes to “US Gallons to Liters Converter”.
- The calculator multiplies by the cubic metre factor of the “from” unit and divides by the factor of the “to” unit: 1 US gal × 0.0037854118 ÷ 0.001 = 3.7854118 L.
1 US gallon in common units
| Unit | Value |
|---|---|
| Litres (L) | 3.7854118 |
| Imperial gallons (UK gal) | 0.83267418 |
| US quarts (US qt) | 4 |
| US pints (US pt) | 8 |
| US cups (US cup) | 16 |
| US fluid ounces (US fl oz) | 128 |
| Cubic feet (ft³) | 0.13368056 |
| Cubic metres (m³) | 0.0037854118 |
US gallons conversion table
| US gallons | L | UK gal | US qt | US pt |
|---|---|---|---|---|
| 0.5 | 1.8927059 | 0.41633709 | 2 | 4 |
| 1 | 3.7854118 | 0.83267418 | 4 | 8 |
| 2 | 7.5708236 | 1.6653484 | 8 | 16 |
| 5 | 18.927059 | 4.1633709 | 20 | 40 |
| 10 | 37.854118 | 8.3267418 | 40 | 80 |
| 50 | 189.27059 | 41.633709 | 200 | 400 |
| 55 | 208.19765 | 45.79708 | 220 | 440 |
| 100 | 378.54118 | 83.267418 | 400 | 800 |
What is a US gallon?
The U.S. liquid gallon is exactly 231 cubic inches, about 3.785 litres. It is used for fuel, milk, water and paint in the United States.
What is a litre?
A litre is one cubic decimetre, 1,000 cm³. Bottles, fuel, engine sizes and many recipes use litres; a litre of water weighs about 1 kg.
What is an imperial gallon?
The imperial gallon is exactly 4.54609 litres, about 20% larger than the U.S. gallon. It was defined as the volume of 10 lb of water and is still used for fuel economy (mpg) in the UK.
Common mistakes to avoid
Mixing u.s. and uk gallons, pints and fluid ounces, assuming a cup is always 250 ml, and treating volume and weight as interchangeable for anything except water.
Formula
1 US gal = 3.7854118 L1 US gal = 0.83267418 UK gal1 US gal = 4 US qt1 US gal = 8 US pt1 US gal = 16 US cupWorked example
Inputs — From: 1 US gal.
Results — To = 3.78541178 L; Imperial gallons = 0.83267418 UK gal; US quarts = 4 US qt; US pints = 8 US pt; US cups = 16 US cup; US fluid ounces = 128 US fl oz; Cubic feet = 0.13368056 ft³; Weight of that much water (20 °C) = 8.33 lb.
Frequently asked questions
How many litres in a gallon?
3.785 L (U.S.) or 4.546 L (UK).
How much does a gallon of water weigh?
About 8.34 lb (3.78 kg) for a U.S. gallon.
How many quarts in a gallon?
4.
How do I change the units?
Pick any unit in the From and To menus. The value is converted in place, and the heading changes to show your conversion, for example “US Gallons to Liters Converter”.
Can I type into any field?
Yes. Every field is editable, so you can start from whichever unit you have.
How many units can I convert between?
27 volume units, from the everyday to the specialised.
Which units are exact?
All factors here are exact by definition except astronomical and similar reference values, which use internationally agreed constants.
What formula does the Gallon Calculator use?
1 US gal = 3.7854118 L.