If you're not used to U.S. gas prices, you might receive two shocks in a row at the gas station. The first is that, compared to many European countries, gas prices here are quite inexpensive. But gas is also usually dispensed by the gallon – a sharp departure from most non-U.K. and non-U.S. countries, where gas is dispensed by the liter. Happily, figuring the equivalent gas price in liters takes only one quick, easy conversion.
TL;DR (Too Long; Didn't Read)
Divide the gas price (per U.S. gallon) by the number of liters in a gallon, 3.78541. The result is the gas price per liter.
Converting U.S. Gallons to Liters
Gas prices in the U.S. are given by the gallon; to convert them to liters, you'll divide the price by the number of liters in a gallon, 3.78541. So if gas costs $3.50 per gallon, you have $3.50 ÷ 3.78541 = $0.92460 per liter, which would typically be rounded to $0.92 per liter.
Just to make things more confusing, there's a difference between the typical U.S. gallon for liquid measure, which contains 3.78541 liters, and the U.K. or imperial gallon, which contains 4.54609 liters. Make sure you're using the right type of gallon before you begin your calculations.
Converting U.K. Gallons to Liters
If you've somehow ended up with gas prices in U.K. gallons, you convert these to liters too – but you must use a different conversion factor. Because there are 4.54609 liters in a U.K. gallon, you'll have to divide the price by 4.54609 to get its equivalent in liters. So if the current gas price is $5.79 per U.K. gallon, the price per liter would be $5.79 ÷ 4.54609 = $1.27362 per liter or, rounding to the nearest penny, $1.27 per liter.