Gallons to Liters Converter

How to use this calculator

1. Decide how many US liquid gallons you need to convert—for example, the size of a fuel tank, a water container, or a brewing batch.
2. Enter that number in the Gallons field. You can use decimals for partial gallons (for example, 2.5 or 0.75).
3. The calculator multiplies your input by 3.78541 to compute liters.
4. Review the liter output and, if needed, round it to the precision your situation requires (for example, one decimal place for tank sizes or two for recipes).
5. Adjust the gallons input to compare different volumes—for example, 1, 5, 10, and 55 gallons—and see the corresponding metric sizes.

Inputs explained

Gallons

The volume in US liquid gallons you want to convert to liters. This is the standard gallon used in most US consumer contexts (gasoline, water jugs, many recipes). If you are working with imperial gallons (UK/Canada), see the note below.

When to use it

• Converting US fuel tank sizes or drum capacities from gallons to liters so you can compare them against vehicles, containers, or equipment specified in metric.
• Translating brewing and winemaking recipes that list gallon batch sizes into liters for metric equipment and fermenters.
• Checking whether a water storage container, rain barrel, or emergency supply barrel labeled in gallons meets a requirement expressed in liters.
• Doing quick mental checks when shopping abroad—for example, comparing a 5-gallon container you are used to with a 20 L container in the store.

Tips & cautions

• Remember that this calculator uses US liquid gallons. Imperial gallons are larger—1 imperial gallon ≈ 4.54609 liters—so conversions will differ if your original measurement is imperial.
• For rough back-of-the-envelope estimates, you can approximate 1 gallon ≈ 3.8 liters, but this tool keeps the more precise 3.78541 factor when you need tighter accuracy.
• Think in reference points: 1 gallon ≈ 3.8 L, 5 gallons ≈ 19 L, 10 gallons ≈ 38 L. Knowing these anchors makes it easier to sanity-check results.
• For fuel economy conversions (like MPG ↔ L/100 km), use a dedicated fuel economy calculator; this tool only handles raw volume conversion.
• Designed for US liquid gallons only; it does not automatically detect or convert imperial or US dry gallons.
• Displayed values are rounded for readability, so you may see minor differences compared with calculators that show more decimal places.
• It does not handle temperature-related volume changes or density differences between fluids—it is a pure unit conversion tool.

Worked examples

Deep dive

FAQs

Is this using US gallons or imperial gallons?

This calculator uses US liquid gallons only. If you need to convert imperial gallons to liters, use the factor 1 imperial gallon ≈ 4.54609 liters or a dedicated imperial gallons to liters converter.

Why doesn’t the displayed result match another calculator exactly?

We use the standard factor 3.78541 and then round results for display. Some tools use slightly different rounding or show more decimal places, which can lead to tiny differences after rounding. The underlying conversion is the same.

Can I use this for any liquid?

Yes, as long as your volume is measured in US liquid gallons, the conversion to liters is purely a unit change and does not depend on the fluid type. Density only matters if you are converting between volume and weight, which this tool does not do.

How can I quickly approximate gallons to liters in my head?

A simple rule of thumb is to multiply gallons by 4 and then subtract about 5%. For example, 10 gallons × 4 = 40; 5% of 40 is 2, so 40 − 2 = 38 liters, which is very close to the precise 37.8541 liters.

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