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Conversion tool

Fuel efficiency converter

Convert between L/100 km, MPG UK, MPG US and km/L. The page also converts EV efficiency between MPGe, mi/kWh, kWh/100 mi and kWh/100 km. Every result names the gallon or energy basis used.

A figure in MPG is ambiguous until you know whether it means UK or US gallons. This converter asks for that choice instead of guessing.

Do not compare UK MPG with US MPG directly

The imperial gallon is 4.54609 litres; the US gallon is 3.785411784 litres. The same numeric MPG is not the same fuel consumption. The ratio between the two is about 1.20095.

Liquid fuel economy

For petrol, diesel and other liquid fuels. Choose the unit your figure is already in.

Your inputs

UK and US MPG use different gallons. Choose the one your figure came from.

L/100 km

Use a dot for decimals, for example 3.5. Do not enter units in the field.

Examples

Estimated result

Liquid fuel economy

Litres per 100 km

5 L/100 km

Lower L/100 km means less fuel used for the same distance.

MPG (UK)

56.5

imperial gallon = 4.54609 L

MPG (US)

47.04

US gallon = 3.785411784 L

Kilometres per litre

20 km/L

System used for input

L/100 km

The output names both MPG systems explicitly.

UK and US MPG differ by a factor of about 1.20095. The calculator never treats them as the same unit.

Electric vehicle efficiency

MPGe is an EPA gasoline-equivalent rating. It is useful for labels and comparisons, but it is not a liquid-fuel measurement. EPA MPGe and kWh/100 mi are wall-to-outlet figures that already include charging losses.

Your inputs

MPGe is an EPA gasoline-equivalent rating, not a liquid-fuel measurement.

MPGe

Use the consumption figure for the same cycle where possible (for example EPA or WLTP).

Examples

Estimated result

Electric vehicle efficiency

MPGe (EPA)

150 MPGe

Based on 33.7 kWh per gallon of gasoline equivalent. EPA MPGe includes charging losses.

Miles per kWh

4.451

EPA wall-to-wheel energy basis

kWh per 100 miles

22.47

Common US EV consumption unit

kWh per 100 km

13.96

Common European EV consumption unit

Input system

MPGe

MPGe is a derived equivalent, not a real liquid-fuel figure.

This is an energy-equivalence conversion. EPA MPGe and kWh/100 mi are wall-to-outlet figures that already include charging losses; do not add losses a second time when comparing them with a charging cost.

The formulas

L/100 km and MPG

MPG (UK) = 282.480936 ÷ (L/100 km)
MPG (US) = 235.214583 ÷ (L/100 km)

L/100 km = 282.480936 ÷ MPG (UK)
L/100 km = 235.214583 ÷ MPG (US)

The constants come from the gallon definitions and 1 mile = 1.609344 km. Zero L/100 km is treated as infinite MPG, not as an error.

EV efficiency

MPGe = mi/kWh × 33.7
mi/kWh = MPGe ÷ 33.7

kWh/100 mi = 100 ÷ (mi/kWh)
kWh/100 km = 62.137119 ÷ (mi/kWh)

33.7 kWh is the EPA gasoline-equivalent basis used by this calculator. EPA MPGe includes Level 2 charging losses and is based on energy at the outlet. Verify the current basis against fueleconomy.gov before relying on a regulatory comparison.

Worked examples

5 L/100 km

56.5 MPG UK

47.04 MPG US

40 MPG UK

7.06 L/100 km

33.31 MPG US

150 MPGe

4.45 mi/kWh

14 kWh/100 km

Reference tables

Static examples for scanning and printing. They use the same tested functions as the calculator.

L/100 km to MPG (UK and US)
L/100 kmMPG UKMPG USkm/L
470.6258.825
556.547.0420
647.0839.216.67
740.3533.614.29
835.3129.412.5
1028.2523.5210
1223.5419.68.33
1518.8315.686.67
2014.1211.765
The same MPG number in each system
MPGL/100 km as MPG UKL/100 km as MPG US
309.427.84
358.076.72
407.065.88
456.285.23
505.654.7
555.144.28
604.713.92
EV efficiency: MPGe to mi/kWh and kWh per 100 miles or kilometres
MPGemi/kWhkWh/100 mikWh/100 km
1002.96733.720.94
1203.56128.0817.45
1303.85825.9216.11
1504.45122.4713.96
1805.34118.7211.63

Questions

How many MPG is 7 L/100 km?
7 L/100 km is about 40.35 MPG UK or 33.60 MPG US. The formula is 282.480936 ÷ 7 for UK MPG and 235.214583 ÷ 7 for US MPG.
How do you convert L/100 km to MPG?
Divide the correct constant by the L/100 km figure. Use 282.480936 for UK imperial MPG and 235.214583 for US MPG. Do not use one constant for both.
Is 40 MPG good?
The number alone is incomplete. 40 MPG UK is about 7.06 L/100 km; 40 MPG US is about 5.88 L/100 km. Whether that is good depends on the vehicle, fuel, route and driving style. Compare like-for-like test cycles.
What is MPGe?
MPGe is the US EPA’s miles-per-gallon-equivalent rating for electric vehicles. It expresses electric energy use using 33.7 kWh per gallon of gasoline equivalent. EPA MPGe includes charging losses and is a label comparison, not a promise of real-world range or cost.
Why can 0 L/100 km produce infinite MPG?
The MPG formula divides by L/100 km. At exactly zero, the mathematical result is infinite. Real vehicles do not use zero fuel, but the converter handles the boundary explicitly rather than crashing.

Sources and definitions

These sources define the units and the EPA basis. They are not live price feeds.

Page last reviewed: . Formulas are covered by automated tests. Prices are inputs, not live data.

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