Gallons to litres
Convert US gallons to litres. Multiply by 3.785411784 for an exact result, with fuel prices, tank sizes and the imperial gallon compared.
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The formula
litres = US gallons × 3.785411784This factor is exact. A US gallon is defined as exactly 231 cubic inches, and an inch is exactly 2.54 cm, so a US gallon is exactly 3.785411784 litres.
To go the other way, divide by 3.785411784. See litres to gallons.
Which gallon
This page converts the US gallon. The imperial gallon used in the UK and Canada is exactly 4.54609 litres — 20% larger:
| Gallons | US → litres | Imperial → litres |
|---|---|---|
| 1 gal | 3.785 L | 4.546 L |
| 2 gal | 7.571 L | 9.092 L |
| 5 gal | 18.927 L | 22.730 L |
| 10 gal | 37.854 L | 45.461 L |
| 15 gal | 56.781 L | 68.191 L |
| 20 gal | 75.708 L | 90.922 L |
Fuel prices
Comparing a price per gallon with a price per litre is the most common reason for this conversion, and it needs dividing rather than multiplying — a price is money per volume, so it moves the opposite way to the volume itself:
| Per US gallon | Per litre |
|---|---|
| $3.00 | $0.79 |
| $3.50 | $0.92 |
| $4.00 | $1.06 |
| $4.50 | $1.19 |
| $5.00 | $1.32 |
A litre price of $1.50 is $5.68 per US gallon, and $6.82 per imperial gallon.
Fuel economy
The same reversal applies to miles per gallon, and here the two gallons matter enormously:
| US mpg | Imperial mpg | Litres per 100 km |
|---|---|---|
| 20 mpg | 24.0 mpg | 11.76 |
| 25 mpg | 30.0 mpg | 9.41 |
| 30 mpg | 36.0 mpg | 7.84 |
| 40 mpg | 48.0 mpg | 5.88 |
| 50 mpg | 60.0 mpg | 4.70 |
A British car advertised at 48 mpg is a US 40 mpg car. Neither figure is wrong; they are measured in different gallons.
Tank and container sizes
| US gallons | Litres | |
|---|---|---|
| Milk jug | 1 gal | 3.79 L |
| Jerry can | 5 gal | 18.93 L |
| Water cooler bottle | 5 gal | 18.93 L |
| Oil drum | 55 gal | 208.20 L |
| Barrel of crude oil | 42 gal | 158.99 L |
Estimating in your head
Multiply by 4 and take off 5%. 15 gallons × 4 is 60, minus 3 is 57 L — the true answer is 56.8 L. For imperial gallons, multiply by 4.5 and the answer is within 0.1%.