Convert Gas Tank Capacity from Gallons to Liters

Direct answer

Multiply the gas tank capacity in US gallons by 3.785411784.

For example, a 15-gallon fuel tank converts as follows:

Rounded to two decimal places, a 15-gallon tank has a nominal capacity of 56.78 liters.

Use the US Gallons to Liters Converter for another vehicle tank size.

How to convert a vehicle tank capacity

1. Confirm that the specification uses US gallons. Imperial gallons require a different conversion factor.
2. Record the complete listed capacity. Include decimal values such as 13.2 or 15.9 gallons.
3. Multiply by 3.785411784.
4. Keep the full result during calculation.
5. Round the final liter value appropriately. One or two decimal places are often enough for comparison.

Common vehicle tank capacities in liters

Example: convert a 13.2-gallon tank

Rounded to two decimal places, the tank capacity is 49.97 liters.

Example: convert a 15.9-gallon tank

Rounded to two decimal places, this is 60.19 liters.

Example: convert a 25-gallon tank

Rounded to two decimal places, this is 94.64 liters.

Nominal capacity versus usable capacity

A published fuel-tank capacity is usually a nominal specification. The amount that can actually be added during a fill-up may differ.

Differences can result from:

• fuel already remaining in the tank;
• unusable reserve volume;
• expansion space;
• tank shape;
• filler-neck capacity;
• pump shutoff behavior;
• vehicle position;
• manufacturer rounding.

Converting the listed capacity does not determine how much fuel can be added at a particular visit.

Fuel tank capacity versus fuel added

Tank capacity and fuel added are separate values. A 16-gallon tank does not require 16 gallons at every fill-up.

The difference reflects fuel that remained in the tank and other practical factors.

Cars, trucks, motorcycles, and boats

The same conversion factor applies to any capacity stated in US liquid gallons.

Motorcycle tank

Pickup truck tank

Boat fuel tank

US gallon versus Imperial gallon tank specifications

A vehicle specification from another market may use Imperial gallons, liters, or US gallons. Confirm the source unit before comparing two vehicles.

Estimating tank capacity mentally

Multiply gallons by 4 for a quick estimate.

A closer estimate is to multiply by 4 and subtract about 5 percent.

Common tank-capacity conversion mistakes

Using the wrong gallon type

US and Imperial gallons are different volumes.

Rounding a decimal capacity first

Convert 15.9 gallons directly rather than changing it to 16 gallons.

Assuming nominal capacity equals fill-up amount

Fuel already in the tank reduces the quantity required at the pump.

Confusing tank size with fuel economy

Tank capacity does not determine miles per gallon or driving range by itself.

Assuming every vehicle trim has the same tank

Capacity can vary by engine, drivetrain, model year, body style, and market.

Related US gallons to liters guides

Frequently asked questions