One US gallon of milk
- Gallons (US)
- 1
Result Liters: 3.7854
- 1 gal × 3.7854 = 3.7854 L
A US gallon jug holds 231 cubic inches, which is just under 3.79 liters.
Gallons to Liters Converter
One US gallon equals exactly 3.785411784 liters, so multiply gallons by 3.785 to get liters. A 5-gallon bucket holds 18.93 liters and a 20-gallon tank about 75.7 liters. The imperial (UK) gallon is larger, at 4.546 liters, so check which gallon your figure uses.
Gallons (US) to Liters conversion table
| gal | L |
|---|---|
| 1 | 3.78541 |
| 2 | 7.57082 |
| 5 | 18.9271 |
| 10 | 37.8541 |
| 20 | 75.7082 |
| 25 | 94.6353 |
| 50 | 189.271 |
| 100 | 378.541 |
| 250 | 946.353 |
| 500 | 1,892.71 |
| 1,000 | 3,785.41 |
About this tool
Fuel economy figures, pool and aquarium sizes, paint tins and American recipes are quoted in gallons, while most of the world measures liquid in liters. This converter turns a US gallon figure into liters as you type and shows the multiplication behind it, so the working can be checked or copied. The US gallon is defined as exactly 231 cubic inches, which fixes the factor at 3.785411784 liters with no rounding in the definition. One limit: this page uses the US liquid gallon only. A British or Canadian imperial gallon is about 20 % bigger, and using the wrong one throws the answer off by that much. Use the swap button to go from liters back to gallons.
How to use it
Enter the volume in gallons
Type the amount into the Gallons (US) field. Decimals work, for example 0.5 for a half gallon.
Read the liters
The liter value updates as you type, together with the multiplication used.
Swap or share
Press Swap to convert liters to gallons, or Share to send a link that reopens the same value.
Examples
A 5-gallon water bottle
- Gallons (US)
- 5
Result Liters: 18.9271
- 5 gal × 3.7854 = 18.9271 L
Office water-cooler bottles and hardware-store buckets hold 5 US gallons, close to 19 liters.
A 20-gallon aquarium
- Gallons (US)
- 20
Result Liters: 75.7082
- 20 gal × 3.7854 = 75.7082 L
Aquarium dosing labels often quote liters, so a 20-gallon tank works out at about 75.7 liters of water before gravel and decor.
How it is calculated
L = gal × 3.785411784
gal- volume in US liquid gallons (231 cubic inches)
L- volume in liters (one cubic decimeter)
The US gallon is defined as 231 cubic inches, and the inch is exactly 2.54 cm, so one gallon is 231 × 16.387064 cm³ = 3,785.411784 cm³. A liter is 1,000 cm³, which gives exactly 3.785411784 liters per gallon. Both units start at zero, so the conversion is a single multiplication.
When not to use it
- Do not use it for UK or Canadian imperial gallons, which hold 4.54609 liters each.
- Do not use it for US dry gallons, an old grain measure of about 4.405 liters.
Common mistakes
- Applying the imperial factor 4.546 to a US figure overstates the liters by about 20 %.
- Rounding the factor to 4 liters per gallon adds a 5.7 % error, which is 11 liters on a 50-gallon drum.
Frequently asked questions
How many liters are in a gallon of gas?
A US gallon of gasoline is 3.785 liters, the same as any other US liquid gallon. Fuel prices per gallon can be divided by 3.785 to get the price per liter.
Why is a UK gallon bigger than a US gallon?
The imperial gallon, adopted in Britain in 1824, was defined as the volume of 10 pounds of water, now fixed at 4.54609 liters. The US kept the older 231-cubic-inch wine gallon, which is 3.785 liters.
How many gallons is one liter?
One liter is about 0.264172 US gallons. That is the reciprocal of 3.785411784, and it is what the swapped direction of this converter uses.
How many liters is half a gallon?
Half a US gallon is 1.8927 liters, so a half-gallon carton of milk holds a little under 1.9 liters.
Is a gallon of water exactly 3.785 kilograms?
Close. Pure water near 4 °C has a density of about 1 kg per liter, so a gallon weighs about 3.78 kg. Warmer water is slightly less dense and weighs a few grams less.
Cite this tool
Using this tool in an assignment, article or report? Copy a citation, or a link for your website.
APA
Tools Directory Editorial Team. (2026, October 25). Gallons to Liters Converter. Tools Directory. Retrieved October 26, 2026, from https://tools.milunir.com/converters/volume/gallons-to-liters-converter/
MLA
Tools Directory Editorial Team. “Gallons to Liters Converter.” Tools Directory, 25 Oct. 2026, https://tools.milunir.com/converters/volume/gallons-to-liters-converter/. Accessed 26 Oct. 2026.
Chicago
Tools Directory Editorial Team. “Gallons to Liters Converter.” Tools Directory. Last modified October 25, 2026. Accessed October 26, 2026. https://tools.milunir.com/converters/volume/gallons-to-liters-converter/.
Link
<a href="https://tools.milunir.com/converters/volume/gallons-to-liters-converter/">Gallons to Liters Converter – Tools Directory</a>