DailySmartTools

Volume Converter

Convert liters, milliliters, US gallons, imperial gallons, quarts, pints, cups and cubic units.

Updated September 19, 2026Checked by the editorial team

US gallons to Liters

3.785412 L

1 gal = 3.785412 L

Show 1 gal in every unit
UnitValue
Milliliters3,785.411784 mL
Liters3.785412 L
Cubic meters0.003785
US fluid ounces128 fl oz
US cups16 cup
US pints8 pt
US quarts4 qt
Imperial gallons0.832674 imp gal
Cubic feet0.133681 ft³
Cubic inches231 in³

Convert liquid and container volumes between metric units, US customary units and imperial units. The list separates US and imperial gallons because they are different sizes, and mixing them up is the most common error.

Cubic meters, feet and inches are included for capacities of tanks, boxes and rooms.

How volume converter works

Everything is converted through liters. A US gallon is defined as exactly 231 cubic inches, which is 3.785411784 liters. An imperial gallon is 4.54609 liters, about 20% more.

Fluid ounces here are US fluid ounces, which measure volume. They are not the same as weight ounces.

The formula

1 US gallon = 3.785411784 L = 4 quarts = 8 pints = 16 cups
1 imperial gallon = 4.54609 L
1 m³ = 1,000 L

Worked example: a fuel tank and a bottle

A 12-gallon US fuel tank holds 12 × 3.7854 = 45.4 L.

A 12-gallon imperial tank holds 12 × 4.546 = 54.6 L.

A 500 mL bottle is 500 ÷ 29.5735 = 16.9 US fluid ounces.

Quick reference

FromTo
1 liter33.814 US fl oz
1 US gallon3.78541 L
1 imperial gallon4.54609 L (1.20095 US gal)
1 US quart0.946353 L
1 US cup236.588 mL
1 m³1,000 L

When to use this converter

  • Comparing fuel economy and tank sizes between countries.
  • Reading drink and recipe volumes.
  • Working out how much water a tank, pool or aquarium holds.

Common mistakes to avoid

  • Using a US gallon when the source is British or vice versa.
  • Assuming a cup is always 250 mL. A US cup is 236.588 mL. For the metric cup, use the cooking converter.
  • Confusing volume ounces with weight ounces.

Frequently asked questions

How many liters are in a gallon?
A US gallon is 3.785 liters. An imperial (UK) gallon is 4.546 liters.
How many cups are in a liter?
A liter is about 4.227 US cups.
How do I convert cubic meters to liters?
Multiply by 1,000. One cubic meter holds 1,000 liters.
Why are there two kinds of gallon?
The US and the British Empire defined the gallon differently before metric units were adopted, and both definitions remain in use.

Learn more

Results are for information only and are not financial, legal or medical advice. The calculation logic is covered by automated tests, and examples on this page are worked out and re-checked before publishing. Spotted a mistake? Tell us.