Fuel Economy Converter

Convert between fuel efficiency (MPG, km/L, mi/L) and fuel consumption (L/100km, gal/100mi) units instantly. Covers US/UK gallons and metric equivalents.

Fuel Economy Converter 6 units

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Common Fuel Economy Conversions

All Fuel Economy Conversions

Browse all unit combinations — each page has a dedicated converter and conversion table.

MPG (US) → MPG (UK) MPG (US) → km/L MPG (US) → mi/L MPG (US) → L/100km MPG (US) → gal/100mi (US) MPG (UK) → MPG (US) MPG (UK) → km/L MPG (UK) → mi/L MPG (UK) → L/100km MPG (UK) → gal/100mi (US) km/L → MPG (US) km/L → MPG (UK) km/L → mi/L km/L → L/100km km/L → gal/100mi (US) mi/L → MPG (US) mi/L → MPG (UK) mi/L → km/L mi/L → L/100km mi/L → gal/100mi (US) L/100km → MPG (US) L/100km → MPG (UK) L/100km → km/L L/100km → mi/L L/100km → gal/100mi (US) gal/100mi (US) → MPG (US) gal/100mi (US) → MPG (UK) gal/100mi (US) → km/L gal/100mi (US) → mi/L gal/100mi (US) → L/100km

📐 How to Use

Choose the unit your figure is in from the From dropdown and the unit you want from the To dropdown; efficiency and consumption units are mixed in one list.
Type the economy figure into the value input and read the converted number live in the To input.
Check the line under the result: it gives the one-unit ratio within a family, or warns that the pair is reciprocal, so a higher input means a lower output.
Flip the direction with the swap button, grab the number with Copy, use the Common Fuel Economy Conversions grid for pairs such as MPG to L/100km, or open All Fuel Economy Conversions for a page with a full conversion table.

❓ Frequently Asked Questions

QWhat is 30 MPG (US) in L/100km?

30 MPG (US) is 7.840481 L/100km. The shortcut is to divide 235.2144 by the MPG figure, since 1 MPG (US) is 0.425144 km/L and L/100km is 100 divided by km/L. So 20 MPG is 11.7607 and 40 MPG is 5.8804.

QHow many MPG is 8 L/100km?

8 L/100km is 29.4018 MPG (US), found by dividing 235.2144 by 8. The constant works in both directions because the relationship is reciprocal, so 6 L/100km is 39.2024 MPG and 10 L/100km is 23.5214 MPG.

QWhy is MPG to L/100km not a simple multiplication?

Because the two units are inverses. MPG counts distance per unit of fuel and L/100km counts fuel per unit of distance, so the converter first turns your value into km/L, then divides into it. Doubling MPG halves L/100km instead of doubling it.

QIs UK MPG the same as US MPG?

No. 30 MPG (UK) is 24.9802 MPG (US), because the imperial gallon holds 4.54609 liters against the US gallon's 3.785412. A UK figure always looks about 20 percent better for the same car, so check which gallon a brochure means.

ℹ️ About Fuel Economy Conversion

Fuel economy is reported in two opposite directions. Efficiency units put distance on top, as in miles per gallon or km/L, so a higher number is better. Consumption units put fuel on top, as in L/100km, so a lower number is better. Crossing between the families is a reciprocal rather than a proportion, which is why lifting a car from 10 to 20 MPG saves far more fuel than going from 40 to 50. Gallons add a second problem: the US gallon is 3.785 liters and the imperial gallon 4.546.

Six units are covered, four efficiency and two consumption. All of them pass through km/L: efficiency units multiply by their factor, consumption units divide their factor by your value, and that division is where the reciprocal appears. Zero is refused because it cannot be inverted. Results are rounded by magnitude, to four decimals from ten upward, inside the page.

📏 6 Supported Units

MPG (US) (mpg), MPG (UK) (mpg UK), km/L (km/L), mi/L (mi/L), L/100km (L/100km), gal/100mi (US) (gal/100mi).