MPG to L/100 km and Other Fuel Economy Conversions

To convert U.S. MPG to liters per 100 kilometers, divide 235.215 by the MPG; to go back, divide 235.215 by the L/100 km figure. The constant comes from the size of a U.S. gallon (about 3.785 liters) and a mile (1.609344 kilometers). U.S. MPG and L/100 km move in opposite directions: a higher MPG is better, while a lower L/100 km is better.

Key takeaways

• L/100 km = 235.215 / MPG (U.S. gallons). A U.S. gallon is not an imperial gallon.
• km per liter = MPG x 0.425144.
• Gallons per 100 miles = 100 / MPG, and it is the unit that adds up like a fuel bill.
• MPGe = 3,370.5 / (kWh per 100 miles), because EPA uses 33.705 kWh per gallon of gasoline-equivalent.

The core conversions

From	To	Formula
MPG (U.S.)	L/100 km	235.215 / MPG
L/100 km	MPG (U.S.)	235.215 / (L/100 km)
MPG (U.S.)	km per liter	MPG x 0.425144
MPG (U.S.)	gallons per 100 miles	100 / MPG
Miles	Kilometers	miles x 1.609344
U.S. gallons	Liters	gallons x 3.785412
kWh per 100 miles	kWh per 100 km	kWh per 100 miles x 0.621371
kWh per 100 miles	MPGe	3,370.5 / (kWh per 100 miles)

The two electricity rows use the EPA’s published factor of 33.705 kilowatt-hours per gallon of gasoline-equivalent, which the EPA rounds to 33.7 in public explanations. The EIA’s conversion pages carry related energy constants if you need them.

Reference table

Values are rounded and computed with the formulas above.

MPG (U.S.)	L/100 km	km per liter	Gallons per 100 miles
15	15.7	6.4	6.67
20	11.8	8.5	5.00
25	9.4	10.6	4.00
30	7.8	12.8	3.33
35	6.7	14.9	2.86
40	5.9	17.0	2.50
50	4.7	21.3	2.00

Use the MPG converter for any other value.

Quick mental math

You do not need a calculator for the common cases. Because the constant is about 235, 47 MPG is about 5 L/100 km, 23.5 MPG is about 10 L/100 km and 31 MPG is about 7.6. Going the other way, a car that uses 8 L/100 km is about 29 MPG (235.215 divided by 8). Always divide the constant by the figure you have, never multiply.

The gallon trap

The U.S. gallon is about 3.785 liters. The imperial gallon used in the United Kingdom is about 4.546 liters, so a given car has a larger MPG figure when it is measured with imperial gallons: multiply U.S. MPG by about 1.201 to get imperial MPG. EPA ratings and everything on this site use U.S. gallons. When you compare a figure from another source, check which gallon it uses.

Ratings from other countries

Converting units does not convert test methods. The EPA’s ratings come from the five test cycles described in how the EPA tests fuel economy, and labels in other markets are produced by their own procedures. A converted EPA number shows what the EPA measured in its terms; it will not match a label from another system, even for the same car.

Why “per 100” units are friendlier

fueleconomy.gov’s label guidance says labels include consumption alongside MPG because it allows more accurate energy-use comparisons between vehicles. Per-100 units scale directly with fuel purchased: halve the L/100 km and you halve the fuel used over the same distance. MPG does not behave that way. The worked table in what is MPG and MPGe shows why a jump from 40 to 50 MPG saves less fuel than one from 15 to 20.

Electric units

kWh per 100 miles is the electric counterpart of gallons per 100 miles. Dividing it by 1.609 gives the energy per 100 kilometers: 30 kWh per 100 miles is about 18.6 kWh per 100 km. To MPGe: 3,370.5 divided by 30 is about 112. Details and sample values are in kWh per 100 miles and EV efficiency.

A worked example

A car rated 30 MPG: 235.215 / 30 = 7.84 L/100 km. Its fuel use over 15,000 miles (about 24,140 km) is 500 U.S. gallons, which is about 1,893 liters. Check: 7.84 L per 100 km times 241.4 (the number of 100 km units in 24,140 km) is about 1,893 liters. For the dollar side, see how annual fuel cost is calculated.