How to Convert Liters to Gallons
Find out how to convert liters to US gallons and imperial gallons using precise conversion factors. Essential for fuel economy, recipe scaling, and international liquid measurements.
US Gallon vs. Imperial Gallon
There are two gallon definitions: the US liquid gallon (used in the United States) equals exactly 3.78541 liters, while the imperial gallon (used in the UK and some Commonwealth countries) equals exactly 4.54609 liters. These are different by about 20 %, so always confirm which gallon is intended before converting — a fuel efficiency figure in miles per imperial gallon will look very different from miles per US gallon.
Liters to US Gallons
US Gallons = Liters ÷ 3.78541 = Liters × 0.264172. A 10-liter fuel can holds 10 × 0.264172 ≈ 2.64 US gallons. A 50-liter gas tank holds 50 ÷ 3.78541 ≈ 13.2 US gallons. The quick approximation is to divide liters by 3.785 or multiply by 0.264.
Liters to Imperial Gallons
Imperial Gallons = Liters ÷ 4.54609 = Liters × 0.219969. A 20-liter water container holds 20 × 0.219969 ≈ 4.4 imperial gallons. United Kingdom fuel economy is measured in miles per imperial gallon — a car achieving 40 mpg (imperial) is only getting about 33 mpg (US) on the same trip.
US Gallons to Liters
Liters = US Gallons × 3.78541. A 5-gallon water jug contains 5 × 3.78541 ≈ 18.9 liters. A swimming pool with a 12,000-gallon capacity holds 12,000 × 3.78541 ≈ 45,425 liters. The inverse of the multiplication-based formula is simply to multiply by the conversion factor in the other direction.
Other Liquid Units in the US System
The US customary liquid system includes: 1 US gallon = 4 quarts = 8 pints = 16 cups = 128 fluid ounces. One fluid ounce = 29.5735 mL. A 2-liter soda bottle holds 2,000 mL ÷ 29.5735 ≈ 67.6 fl oz ≈ 2.11 quarts. Knowing these sub-units helps when converting recipes from US customary to metric.
Fuel Economy Conversion
Fuel economy in L/100km (metric) and mpg (US) convert as: mpg (US) = 235.215 ÷ L/100km. A car rated at 7 L/100km achieves 235.215 ÷ 7 ≈ 33.6 mpg (US). Conversely, L/100km = 235.215 ÷ mpg (US): a 30 mpg car uses 235.215 ÷ 30 ≈ 7.84 L/100km. Note that lower L/100km is better (less fuel used) while higher mpg is better.
Aquarium and Agricultural Uses
Aquarium capacity is frequently listed in gallons in the US and liters elsewhere: a 20-gallon tank holds 20 × 3.785 ≈ 75.7 liters. Irrigation water, rainfall measurement, and chemical spray applications also cross between these systems. Agricultural spray rates in gallons per acre convert to liters per hectare by multiplying by 9.354 (since 1 acre ≈ 0.4047 ha and 1 US gallon ≈ 3.785 L).
Try These Calculators
Put what you learned into practice with these free calculators.
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