US products from water heaters to paint cans to homebrew kits are sized in gallons. If you’re working with metric equipment, following a recipe from abroad, or calculating water use in liters, this converter gives the exact figure — and shows the imperial-gallon result too, because a “gallon” from a British source is about 20% bigger.
How to use the gallons to liters converter
- Enter a volume in US gallons (gal).
- Read the result in liters. The row If UK (imperial) gallons shows the liters if your number was actually in imperial gallons; cubic meters are listed for large tanks.
- The chart lists 0.25 to 1,000 gallons, with a column for the imperial interpretation.
Gallons to liters formula
The factor is exact. The US gallon is defined as 231 cubic inches, and since an inch is exactly 2.54 cm, 231 × 16.387064 cm³ = 3,785.411784 cm³, which is 3.785411784 L.
For imperial gallons, use 4.54609 instead.
Worked example: a 5-gallon homebrew batch
Step 1. 5 × 3.785411784 = 18.9271 L.
Step 2. A 20-liter fermenter therefore has about 1 L of headspace — too little for a vigorous fermentation, which is why 23 L and 30 L vessels are popular.
If the recipe is British. 5 imperial gallons is 22.7305 L, a noticeably larger batch.
Household containers and appliances
| Item | US gallons | Liters |
|---|---|---|
| Milk jug | 1 | 3.79 |
| Large water jug | 2.5 | 9.46 |
| Hardware-store bucket | 5 | 18.93 |
| Kitchen trash bag | 13 | 49.21 |
| Small water heater | 40 | 151.42 |
| Standard water heater | 50 | 189.27 |
| Steel drum | 55 | 208.2 |
| Mid-size aquarium | 75 | 283.91 |
Water heaters sold outside North America are rated in liters, so a 50-gallon US unit corresponds to roughly a 190 L or 200 L model.
Inside a gallon
| US unit | Per gallon | Milliliters |
|---|---|---|
| Quart | 4 | 946.35 |
| Pint | 8 | 473.18 |
| Cup | 16 | 236.59 |
| Fluid ounce | 128 | 29.57 |
This is useful for scaling recipes: a quart of stock is just under a liter, and a liter is about 4.2 cups. For teaspoons and tablespoons, the cooking converter has the full set of kitchen measures.
US vs imperial gallons
The two gallons have different histories. The US kept the old English wine gallon of 231 cubic inches. Britain replaced its various gallons in 1824 with the imperial gallon, originally the volume of 10 pounds of water, now fixed at 4.54609 L. One imperial gallon equals about 1.2 US gallons. The same split runs through the smaller units: an imperial pint is 568 mL against the US pint’s 473 mL, though the imperial fluid ounce (28.41 mL) is slightly smaller than the US one (29.57 mL), because there are 20 of them in an imperial pint instead of 16.
Large volumes
For pools, cisterns and tanks, liters get unwieldy, so the result is also given in cubic meters (1 m³ = 1,000 L). A 10,000-gallon above-ground pool holds 37.85 m³. To size a tank from its dimensions, use the tank volume calculator. For the reverse conversion, see liters to gallons.
Frequently asked questions
How many liters are in a gallon?
A US gallon is exactly 3.785411784 liters, usually rounded to 3.785 or 3.79. An imperial (UK) gallon is 4.54609 liters.
How many liters is 5 gallons?
5 US gallons is 18.9271 liters. If the recipe or container is British, 5 imperial gallons is 22.7305 liters.
How many liters is a 55-gallon drum?
55 US gallons is 208.2 liters, which is why the same steel drum is sold as a 208 L or 210 L drum outside the US.
How many quarts, pints and cups are in a gallon?
One US gallon is 4 quarts, 8 pints, 16 cups or 128 fluid ounces. In metric, a quart is 946.35 mL, a pint 473.18 mL and a cup 236.59 mL.