How many liters are in 5 gallons?

5 × 3.78541 = 18.93 liters. 5 US gallons is the standard water cooler bottle size.

Is a UK gallon the same as a US gallon?

No. A UK imperial gallon is 4.54609 liters, about 20% larger than a US gallon (3.78541 L).

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US Gallons to Liters Converter

Q: How many liters are in a US gallon?

1 US gallon equals 3.78541 liters. Multiply gallons by 3.78541 to convert.

Convert US gallons to liters instantly with a live calculator, a fuel and container chart, and the manual math.

💧 Gallons to Liters Calculator

US Gallons

Result (liters)

5 US gal = 18.93 L (water cooler bottle)

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Gallons to Liters in Practice

The US gallon is used for gasoline, milk, paint, and water in the United States, while liters dominate almost everywhere else. Someone comparing fuel prices between the US and Canada, or checking the capacity of an imported water heater or fuel tank, needs this conversion. Since one US gallon is 3.785 liters, a 10-gallon tank is about 38 liters, and a full US gas tank of 15 gallons is about 57 liters.

Household products trigger it too: laundry detergent jugs, fish tanks, garden sprayers, and emergency water storage are labeled in gallons in the US and liters internationally. A quick caution: the UK imperial gallon is 4.546 liters, about 20% larger. This page converts US gallons, which are used in North America and most consumer products in the Americas.

liters = US gallons × 3.78541

Common Mistakes to Avoid

Assuming the UK gallon. US gallon = 3.785 L; UK gallon = 4.546 L. Using the wrong one makes a 20% error.
Dividing instead of multiplying. A liter is smaller than a gallon, so the liter result must always be larger than the gallon value.
Rounding 3.785 down to 3.5. That is a 7.5% error. For fuel and aquariums, use 3.78541.
Mixing volume with weight. A US gallon of water weighs 8.34 lb (3.785 kg), but that is mass, a different conversion entirely.

Worked Example by Hand

Convert 12 US gallons to liters:

Write the factor: 1 US gal = 3.78541 L.
Multiply: 12 × 3.78541 = 45.4249 L.
Round to two decimals: 45.42 L.
So 12 US gal = 45.42 L, a common fish tank size.

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Gallons to Liters Reference Chart

US Gallons	Liters	US Gallons	Liters	US Gallons	Liters
0.5 gal	1.89 L	3 gal	11.36 L	10 gal	37.85 L
1 gal	3.79 L	4 gal	15.14 L	12 gal	45.42 L
1.5 gal	5.68 L	5 gal	18.93 L	15 gal	56.78 L
2 gal	7.57 L	6 gal	22.71 L	20 gal	75.71 L
2.5 gal	9.46 L	8 gal	30.28 L	30 gal	113.56 L
2.75 gal	10.41 L	9 gal	34.07 L	50 gal	189.27 L

Memory anchor: 1 gallon is about 3.8 liters, so a 5-gallon cooler bottle is about 19 liters, and a 15-gallon car tank is about 57 liters.

Frequently Asked Questions

How many liters are in a US gallon?

Exactly 3.785411784 liters. The UK imperial gallon is 4.54609 liters.

How many liters is a 5-gallon bottle?

5 × 3.78541 = 18.93 liters, the standard water-cooler bottle size.

How many liters is a full car gas tank?

A typical 15-gallon US tank holds 56.78 liters. Compact cars often hold 12-13 gallons, or 45-49 liters.

Which gallon should I use for recipes?

US recipes use the US gallon (3.785 L). UK and Commonwealth recipes historically use the imperial gallon, though most now use liters directly.

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