Calculators & Converters

Fuel Economy Converter

Compare distance-per-fuel and fuel-per-distance measurements with the gallon convention stated. Enter a trip distance to estimate fuel use at the converted consumption rate.

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Compare fuel economy conventions

Choose US or Imperial mpg explicitly. All amounts must be greater than zero because economy and consumption are reciprocal.

Trip fuel estimate

Assumes the same consumption for the whole trip. Traffic, speed, weather, and load can change actual fuel use.

Converted amount

30 miles per US gallon (mpg US)≈ 7.84048611

liters per 100 kilometers (L/100 km)

39.2024306liters for your trip
10.3561865US gallons for your trip

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

Equivalent units

UnitAmount
liters per 100 kilometers (L/100 km)7.84048611
kilometers per liter (km/L)12.7543112
miles per US gallon (mpg US)30
miles per Imperial gallon (mpg Imp)36.0284978
liters per kilometer (L/km)0.0784048611
US gallons per 100 miles3.33333333

Displayed values are rounded. CSV uses the available JavaScript numeric precision; it cannot restore precision absent from the input.

Calculations and CSV generation run locally in your browser. No measurement data is uploaded by this tool.

GET STARTED

How to use the Fuel Economy Converter

  1. 01

    Enter a strictly positive economy or consumption value and choose the correct unit, especially US versus Imperial mpg.

  2. 02

    Select your target unit. Enter a trip distance in kilometers if you want a constant-consumption fuel estimate.

  3. 03

    Read both the chosen result and unit table. Copy the selected conversion or download the table without the separate trip scenario.

Examples

US mpg to consumption

30 mpg US is about 7.840486 L/100 km. Over 500 km, that rate corresponds to about 39.2024 liters, assuming the same consumption throughout.

Imperial and US gallons

The same vehicle at 30 mpg US is about 36.0285 mpg Imperial. An Imperial gallon is larger, so the numerical miles-per-gallon value is higher.

Economy as kilometers per liter

20 km/L equals 5 L/100 km. Doubling distance per liter halves fuel used per distance; it does not double the L/100 km value.

The reciprocal relationship

Fuel economy such as km/L describes distance gained per fuel volume. Consumption such as L/100 km describes fuel needed per distance. In these two units, L/100 km = 100 ÷ km/L. That inverse relationship means the same absolute improvement in mpg does not always save the same amount of fuel.

Gallon and mile definitions

Calculations use 1 mile = 1.609344 km, a US liquid gallon = 3.785411784 L, and an Imperial gallon = 4.54609 L. The reciprocal constants are derived from those unit factors rather than rounded shortcut values. Labels state US or Imperial everywhere a gallon appears.

Trip estimates and comparisons

Trip fuel equals distance in kilometers multiplied by L/100 km and divided by 100. It assumes the entered consumption applies to the whole trip. To combine multiple journeys, add their fuel and distance separately before calculating an overall rate. An unweighted average of mpg values can misstate the total.

What to know

  • All source values must be greater than zero; infinity and ideal zero-fuel cases are not represented.
  • The trip estimate assumes constant consumption. It is not a test-cycle comparison, emissions estimate, or vehicle specification.
  • Decimal and scientific notation are supported; commas and unit text are not. Calculations use JavaScript floating-point numbers and displayed results are rounded.

Common questions

Why does zero show a validation error?

Zero consumption corresponds to no finite distance-per-fuel value, while zero economy has no finite fuel-per-distance equivalent. This converter requires positive input so that its full reciprocal table remains finite.

Is a higher number always better?

Higher mpg or km/L means more distance per fuel. Lower L/100 km or gallons per 100 miles means less fuel per distance.

Does this calculate MPGe for electric vehicles?

No. MPGe needs an energy-equivalence convention. These options convert liquid fuel volume and distance only.

Will this predict my vehicle’s real consumption?

It estimates fuel at the rate you enter. It does not use a vehicle database or adjust for driving conditions, vehicle load, weather, or route.

Sources & references