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US gallons to liters (gal to L)

To convert US gallons to liters (gal to L): one US gallon is 3.7854118 liters, so 15 gal is 56.7812 L.

Swap units: L to gal

In liters56.7812 L

Conversion factor Exact by definition. The inch has been exactly 2.54 cm and the pound exactly 0.45359237 kg since the 1959 international yard and pound agreement, so these are not measurements that can drift.
1 US gallon = 3.785411784 liters
The other way
1 liter = 0.2641720524 US gallons
Working
15 x 3.785411784 = 56.7812
15 gal in every unit
56,781 ml 56.781 L 11,520 tsp 3,840 tbsp 1,920 fl oz 240 cup 120 pt 60 qt 15 gal 12.49 imp gal 2.0052 cu ft 0.074267 cu yd 0.056781 m3
US gallons to liters
galL
13.78541
27.57082
518.9271
1037.8541
2594.6353
50189.271
100378.541

How the Unit Converter works

One US gallon is 3.785411784 liters. Both units are defined against the same SI base unit, so the factor is derived from two exact definitions rather than measured. It is exact in principle and does not land on a round number.

Worked through: 10 gal x 3.78541178 = 37.8541 L.

Going the other way, one liter is 0.2641720524 US gallons.

To convert without a calculator, multiply by 3.785. Rounding that to 3.8 is within 0.39% for most purposes.

A US gallon, which is 3.785 liters and NOT the imperial gallon of 4.546. The 20% gap matters most for fuel: a car doing 30 mpg in Britain does about 25 mpg by American measurement, and the difference is entirely the gallon.

Precision is worth matching to the input. A measurement given as 1 gal carries one or two significant figures, and reporting its conversion to six implies a precision the original never had.

Unit Converter FAQ

How many liters are in a US gallon?

3.7854118. The factor is derived from the definitions of both units against the same SI base, so it is exact in principle but not a round number.

What is 15 gal in liters?

56.7812 L. Multiply by 3.7854118: 10 gal x 3.78541178 = 37.8541 L.

How do I convert liters back to US gallons?

Divide by 3.7854118, or equivalently multiply by 0.26417205. One liter is 0.26417205 US gallons. The two factors are reciprocals, so you only need to remember one of them.

Is there anything to watch out for with this conversion?

A US gallon, which is 3.785 liters and NOT the imperial gallon of 4.546. The 20% gap matters most for fuel: a car doing 30 mpg in Britain does about 25 mpg by American measurement, and the difference is entirely the gallon.

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