Gallons to Liters conversion

Gallons to liters

The gallon on this page is the US liquid gallon, 3.78541 liters, the unit used for fuel, milk, paint and swimming pools in the United States. The imperial gallon used historically in the UK, Canada and Ireland is larger, 4.54609 liters, so a British "miles per gallon" figure is not comparable to an American one without adjustment.

The formula

Multiply gallons by 3.78541. For a rough estimate use 3.8, or remember that 1 gallon is a little less than 4 liters and 5 gallons is a little less than 19 liters.

• 1 gal = 3.79 L
• 2 gal = 7.57 L
• 5 gal = 18.93 L
• 10 gal = 37.85 L
• 15 gal = 56.78 L (a typical car fuel tank)
• 20 gal = 75.71 L
• 50 gal = 189.27 L
• 100 gal = 378.54 L

Fuel

Petrol is sold by the gallon in the US and by the liter almost everywhere else. To compare prices, divide the price per gallon by 3.785: $3.50 per gallon is $0.92 per liter. To convert fuel economy, 1 mile per US gallon is 0.425 km per liter; a more useful figure is liters per 100 km, which equals 235.2 ÷ mpg.

Water and containers

Aquariums, water heaters, rain barrels and hot tubs are sized in gallons in the US and liters elsewhere. A 50-gallon water heater holds 189 liters; a 20-gallon fish tank is 76 liters. Domestic water use is often quoted as 80–100 gallons per person per day, roughly 300–380 liters.

Gallons, quarts and pints

One US gallon is 4 quarts, 8 pints or 16 cups, and 128 fluid ounces. Because the imperial gallon has 160 fluid ounces, an imperial pint (568 ml) is bigger than a US pint (473 ml) — the reason British beer glasses look generous to American visitors.

Worked examples

A 12-gallon fuel tank. 12 × 3.78541 = 45.4 l. At €1.80 per liter a full tank costs about €82.

A 55-gallon drum. 55 × 3.78541 = 208 l — the metric world calls it a 200-liter drum.

A 10 000-gallon pool. 10 000 × 3.78541 = 37 854 l, or 37.9 m³ — the figure needed for metric pool-chemical dosing.

Frequently asked questions

How many liters are in a gallon? 3.785 in a US gallon, 4.546 in an imperial gallon.

Which gallon does this converter use? The US liquid gallon of 231 cubic inches. Use it for anything sold in the United States.

How do I convert mpg to L/100 km? Divide 235.21 by the mpg figure: 30 mpg (US) is 7.8 L/100 km.

Related conversions

A gallon is 4 quarts, 8 pints or 128 fluid ounces; fluid ounces to liters covers the smaller sizes. Liters to gallons is the reverse of this page.

Good to know

Water usage figures are quoted in gallons in the US and in litres elsewhere, and the difference between the two gallons matters for comparisons. A US shower head limited to 2.5 gallons per minute delivers 9.5 l/min; a European "9-litre" head is the same thing. A typical American household uses 300 gallons a day, about 1 135 litres; the European average is closer to 150 litres per person. Toilets are labelled 1.6 gallons per flush (6 l) or 1.28 gpf (4.8 l) in the US and 6/3 litres dual-flush in Europe.