🛢️ Gallons to Liters Converter

What is the Gallons to Liters Converter?

The word gallon means two different volumes depending on where you are. In the United States, a gallon is a US liquid gallon, defined as 231 cubic inches, which works out to exactly 3.785411784 liters. This tool rounds that to 3.78541 liters per gallon, the same precision used by most gallons to liters converters and reference charts, which is accurate enough for cooking, fuel, gardening, and virtually every everyday or professional calculation.

The United Kingdom, along with several Commonwealth countries in older contexts, uses the imperial gallon instead, and it is a noticeably larger unit: 1 imperial gallon equals exactly 4.54609 liters. That is roughly 20 percent more volume than a US gallon, so mixing the two up is a common and sometimes costly mistake, especially for fuel economy figures, recipe scaling, or ordering large containers of liquid across borders. This is exactly why this gallons to liters converter shows both figures side by side instead of assuming you mean one or the other.

Running the gallons to liters formula in reverse converts liters back to gallons. Divide the liter value by 3.78541 to get US gallons, or divide by 4.54609 to get UK imperial gallons. Because a liter is smaller than a US gallon, the gallon figure is always the smaller number when you convert liters to US gallons, and multiplying instead of dividing is one of the most frequent errors people make when doing this conversion by hand.

Knowing which gallon to use matters in practice. US recipes, US fuel economy ratings in miles per gallon, and US container sizes almost always mean the US liquid gallon. UK fuel prices, older British recipes, and some Commonwealth industrial specifications use the imperial gallon instead. Whether you are converting gallons to liters for a US recipe or working the other way for a UK one, checking the gallon type first avoids an easy mistake. If you are turning a US gallon figure into liters for an American car fuel tank, a US grocery jug, or a home brewing recipe from a US source, use the US gallon result. If the source is British or explicitly says imperial, use the UK figure shown underneath it.

When to use it

• Converting a car's fuel tank capacity from gallons to liters when comparing a US-spec vehicle to a European model.
• Scaling a recipe or home brewing batch listed in US gallons into liters for a metric kitchen or brewing setup.
• Working out how many liters of paint, water, or fuel you need after seeing a quantity printed in gallons on packaging.
• Checking whether a UK imperial gallon measurement matches a US gallon figure before ordering supplies internationally.
• Converting liters back into gallons to make sense of a European fuel consumption figure in US gallon terms.
• Sizing a fish tank, drum, or storage tank quoted in gallons by converting it into liters for a metric spec sheet.

How to use the Gallons to Liters Converter

1. Type a value into the US Gallons field to see it converted into liters instantly.
2. Or type a value into the Liters field to convert liters back into US gallons.
3. Check the UK (imperial) gallon readout underneath for the British equivalent of the same liter value.
4. Use the Copy button to copy the full result line, or Reset to return to the 10-gallon starting example.

Formula & method

Worked examples

US gallons to liters conversion chart (1 US gal = 3.78541 L)

Liters to US and UK gallons quick reference

Common mistakes to avoid

• Treating US and UK gallons as the same size. They are not close: a UK imperial gallon (4.54609 L) is about 20 percent larger than a US gallon (3.78541 L). Always confirm the source country before converting gallons to liters for fuel, recipes, or shipping, or you will be off by a fifth.
• Rounding the conversion factor too aggressively. Rounding 3.78541 down to 3.8, or worse, to 4, looks close but drifts fast. Over 100 gallons that rounding error adds up to several liters of difference, enough to matter for fuel, chemicals, or bulk liquid orders.
• Comparing US and UK miles per gallon without converting the gallon first. US car reviews report miles per US gallon, while UK reviews report miles per imperial gallon. A "40 MPG" claim can mean noticeably different real-world fuel use depending on which gallon is behind the number, so convert the gallon size before comparing efficiency figures.
• Dividing instead of multiplying, or the other way around. To turn US gallons into liters you multiply by 3.78541; to turn liters back into gallons you divide by the same number. Doing it backwards gives a gallon figure that looks far too large, or a liter figure that looks far too small.

Glossary

US gallon (liquid)

The US customary volume unit, defined as 231 cubic inches, equal to exactly 3.785411784 liters, rounded to 3.78541 liters for everyday use.

UK (imperial) gallon

The British imperial volume unit, equal to exactly 4.54609 liters, about 20 percent larger than a US gallon.

Liter (L)

The metric unit of volume, equal to one cubic decimeter or 1,000 milliliters, used almost everywhere outside the United States.

Conversion factor

The fixed number you multiply or divide by to change units, here 3.78541 for US gallons and 4.54609 for UK imperial gallons.

Quart

A US customary volume unit equal to one quarter of a US gallon, or about 0.946 liters.

MPG (miles per gallon)

A fuel economy measure that differs between countries because the underlying gallon differs, US MPG uses the US gallon and UK MPG uses the imperial gallon.

Frequently asked questions