Free Liters to Gallons Converter — US Gallons, Exact Factor

What is a liter, and what is a US gallon?

The liter is a unit of volume equal to 1 cubic decimeter — 0.001 cubic meters. Fuel is sold by the liter across Europe, the United Kingdom and most of the world, and drinks, engine oil and cleaning products are labelled in liters and milliliters. A liter of water weighs very close to 1 kilogram, which is one reason the metric system feels tidy: volume, length and mass all line up.

The US gallon is the customary unit of volume in the United States, defined as exactly 231 cubic inches, which is 3.785411784 liters. Petrol, milk and paint are all sold by the US gallon in America. Do not confuse it with the UK (imperial) gallon, defined by the Weights and Measures Act 1985 as exactly 4.54609 liters — about 20.1 percent larger. The word gallon on its own is ambiguous: this converter says US gallons explicitly, everywhere, and shows UK gallons only where it names them.

How to use the converter

1. Type a volume in the Liters box — the US gallons result appears instantly, with no button to press.
2. Or type in the US gallons box instead: the converter works both ways, so the liters value updates at once.
3. Use the Swap button to reverse the direction. The converted value carries over as the new starting number.
4. Read the result line under the boxes: it shows the full conversion plus the one-unit rate, 1 liter = 0.26417 US gallons. For UK gallons, use the table below.

Liters to gallons formula

This converter divides by the exact 3.785411784 rather than multiplying by the rounded 0.264172, so converting there and back returns the number you started with. The two methods agree to 6 decimals; the division is the exact one.

Worked example

You fill a car in France with 38 liters of petrol. How many US gallons is that — and how many UK gallons?

Try 38 in the converter above, then type the US gallons result in the right-hand box to watch it return 38 liters.

Liters to gallons conversion table

US gallons use the exact factor 3.785411784 liters; UK (imperial) gallons use exactly 4.54609 liters. One UK gallon is about 20.1 percent larger than one US gallon. Values rounded to 4 decimal places.

Fuel tanks and everyday volumes

• Small car tank — 40 liters = %40/3.785411784:4% US gallons (%40/4.54609:4% UK gallons).
• Family car tank — 50 liters = 13.2086 US gallons (%50/4.54609:4% UK gallons).
• Large SUV tank — 60 liters = %60/3.785411784:4% US gallons (%60/4.54609:4% UK gallons).
• Jerry can — 20 liters = %20/3.785411784:4% US gallons.
• Drinks bottle — 1 liter = %1/3.785411784:4% US gallons; 2 liters = %2/3.785411784:4% US gallons.
• Engine oil — 5 liters = %5/3.785411784:4% US gallons.
• Fuel economy warning — mpg figures differ between the US and the UK because the gallons differ: the same car shows a higher mpg number in the UK. Never compare US mpg with UK mpg directly.

Comparing fuel prices across countries? Our metric vs imperial conversion guide for Europe explains liters, gallons and pump prices, and which unit each country uses.

Frequently asked questions

How many US gallons is 1 liter?

One liter is 0.264172 US gallons (1 ÷ 3.785411784 = 0.264172052, shown rounded to 6 decimals). The US gallon is defined as exactly 231 cubic inches, which is 3.785411784 liters, so dividing by 3.785411784 is exact.

What is the difference between a US gallon and a UK gallon?

A US gallon holds 3.785411784 liters, while a UK (imperial) gallon holds 4.54609 liters exactly — about 20.1 percent more. So 50 liters is 13.2086 US gallons but only 10.9985 UK gallons. Always check which gallon a figure uses before comparing fuel prices or economy.

How many US gallons is 50 liters?

50 liters is 13.2086 US gallons (50 ÷ 3.785411784 = 13.208602, rounded to 4 decimals). In UK gallons, 50 liters is 10.9985 gallons.

How do I convert gallons back to liters?

Multiply US gallons by 3.785411784: 10 US gallons × 3.785411784 = 37.8541 liters. For UK gallons, multiply by 4.54609 instead: 10 UK gallons is 45.4609 liters. Type in the right-hand box above and the converter does the reverse for you.

Why does the US use gallons while Europe uses liters?

Fuel is sold by the liter across Europe and in most of the world, following the metric system, while the United States kept its customary gallon for fuel, milk and paint. Visitors comparing fuel prices across the Atlantic must convert both the volume and the currency before the comparison means anything.

Can I convert liters per 100 km to miles per gallon here?

Not directly — fuel economy needs distance as well as volume. The volume part uses this page's factor, but L/100 km and mpg also invert the ratio (fuel per distance versus distance per fuel), so the conversion is 235.214 ÷ L/100 km for US mpg. This page converts volumes only.

Is the liters to gallons conversion exact?

Yes, for US gallons: the US gallon is defined as exactly 231 cubic inches, which equals exactly 3.785411784 liters, so the division is exact. UK gallons are also exact at 4.54609 liters under the Weights and Measures Act 1985. Only the decimals shown on screen are rounded.

Sources

• NIST Special Publication 811, Guide for the Use of the International System of Units (SI) — nist.gov/pml/special-publication-811
• BIPM, The International System of Units (SI Brochure) — bipm.org
• NIST Handbook 44, Appendix C — 1 US gallon = 231 cubic inches = 3.785411784 liters exactly.
• UK Weights and Measures Act 1985 — 1 imperial (UK) gallon = 4.54609 liters exactly.

Conversion factors checked against these sources on 14 November 2026.

Disclaimer: this page converts US gallons unless a UK gallon is named; double-check which gallon applies before ordering fuel or parts.

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