Convert Fuel Gallons to Liters

Direct answer

Multiply US gallons of fuel by 3.785411784.

For example, 12 US gallons of fuel converts to:

Rounded to two decimal places, this is 45.42 liters.

How to convert a fuel quantity

1. Confirm the gallon system. US and Imperial gallons are different volumes.
2. Record the complete quantity. Include decimal digits shown on the pump or receipt.
3. Multiply by 3.785411784.
4. Round according to the purpose. Receipts and records may use two or three decimal places.
5. Keep the fuel type separate. The unit conversion is the same for gasoline and diesel, but product properties and prices can differ.

Common fuel quantities in liters

Example: convert 9.5 gallons of fuel

Rounded to two decimal places, this is 35.96 liters.

Example: convert 14.2 gallons

The complete calculated result is 53.753? liters.

Example: convert 18.5 gallons

Rounded to two decimal places, this is 70.03 liters.

Gasoline and diesel use the same volume conversion

The gallon-to-liter calculation converts volume, so the same factor applies to gasoline, diesel, and other liquids measured in US liquid gallons.

The conversion does not make different fuels physically identical. Fuels can differ in:

• density;
• energy content;
• grade and formulation;
• temperature behavior;
• price;
• vehicle compatibility.

US gallons and Imperial gallons in fuel records

Fuel economy and pump quantities may use US gallons in the United States and Imperial gallons in some other contexts.

Using the wrong gallon system can materially change a tank, consumption, or cost comparison.

Converting a fuel receipt

A receipt may show gallons dispensed to three decimal places. Preserve that full quantity during conversion.

Example receipt

Round the final liter quantity according to the record or reporting requirement rather than shortening the gallon input first.

Converting fuel price per gallon to price per liter

Volume conversion alone does not automatically calculate an accurate international price comparison because currencies, taxes, grades, and fees may differ.

When the price uses the same currency and fuel product, a basic unit-price conversion is:

Example using $4.00 per US gallon

This only changes the volume basis. It does not convert currency or account for different tax structures.

Fuel economy is a separate conversion

Converting gallons to liters does not by itself convert miles per gallon into liters per 100 kilometers. That calculation also changes the distance unit and reverses the way consumption is expressed.

Keep these tasks separate:

• fuel volume in gallons to liters;
• distance in miles to kilometers;
• fuel economy in mpg to L/100 km;
• fuel cost per gallon to cost per liter.

Tank capacity versus fuel added

A vehicle may have a 15-gallon tank but receive only 11 gallons at a fill-up. Tank capacity and fuel dispensed are different quantities.

The remaining difference may include existing fuel, unusable reserve, expansion space, or nominal capacity rounding.

How to estimate fuel gallons in liters

Multiply gallons by 4 for a quick estimate.

A closer estimate multiplies by 4 and subtracts approximately 5 percent.

Temperature and measured fuel volume

Liquid volume can change slightly with temperature. Commercial fuel systems may use measurement standards, compensation methods, and regulatory rules that are outside a basic unit conversion.

The calculator converts the reported gallon quantity. It does not adjust that quantity for temperature, density, or measurement-system calibration.

Common fuel conversion mistakes

Using Imperial gallons for a US fuel quantity

Confirm the gallon definition before calculating.

Rounding pump gallons before conversion

Preserve the decimal quantity shown on the receipt.

Confusing tank capacity and fuel added

A full tank specification does not identify the amount purchased.

Treating volume conversion as fuel-economy conversion

Miles per gallon and liters per 100 kilometers require another formula.

Ignoring currency and tax differences

Price-per-unit conversion does not make fuel prices from different markets directly comparable.

Use the US Gallons to Liters Converter for another fuel volume.

Related US gallons to liters guides

Frequently asked questions