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Gallons to Litres

Convert US gallons to litres, with imperial shown as well.

Inputs
gal

The number of us gallons to convert.

Litres
56.78L
If imperial gallons
68.19L
1 gal
3.79L
5 gal
18.93L
15 gal
56.78L
20 gal
75.71L
litres = US gallons × 3.785411784

1 gal = 3.785412 L

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Multiply US gallons by 3.785 to get litres, or by 4.546 for imperial gallons. Always establish which gallon a figure refers to before converting — the two are twenty percent apart.

How to use Gallons to Liters Converter

  1. Enter the value. Decimals are fine.
  2. Read the conversion. Both systems are shown, so you can see which one your source meant.

About converting gallons to litres

Converting gallons to litres is straightforward once you know which gallon you have, and that is the whole difficulty. The US gallon of 3.785411784 litres descends from the English wine gallon of 231 cubic inches; the imperial gallon of 4.54609 litres was defined separately in 1824 and is about twenty percent larger. A vehicle tank, a fuel price or a chemical quantity quoted in gallons is therefore ambiguous unless the source is known, and the error when you guess wrong is far too large to absorb. There is a third gallon most people never encounter directly. The US dry gallon of 4.405 litres was used for produce and grain, and while the unit itself has fallen out of use its subdivisions have not — the US dry pint and dry quart are still legal measures for fruit and vegetables, which is why a pint of blueberries and a pint of milk are genuinely different volumes. Beyond the units, volume is temperature-dependent in a way weight is not. Liquids expand as they warm, so a fixed volume of fuel contains less energy when delivered warm than cold, which is why some jurisdictions mandate temperature compensation at the pump and others leave the difference with the customer.

Frequently asked questions

How many litres is a 15 gallon tank?
About 57 litres if the figure is US gallons, or 68 if imperial. That gap is a quarter of a tank, which is why vehicle specifications published for one market mislead in the other.
Which gallon does a recipe mean?
Almost always the US gallon if the recipe is American, and the imperial one if it is British and old enough to use gallons at all. Modern British recipes use millilitres, precisely because the ambiguity was intolerable.
Does temperature affect the conversion?
Not the arithmetic, but it affects what you get. Liquids expand when warm, so a gallon of fuel delivered at thirty degrees contains slightly less mass than the same volume at ten. Some jurisdictions require pumps to compensate; most do not.
What about dry gallons?
The US also has a dry gallon of 4.405 litres, used historically for grain and produce. It is largely obsolete but survives in the US dry pint and quart, which is why a pint of blueberries is not a pint of milk.

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