MPG vs L/100km: How to Compare Without Doing Mental Math

Americans say MPG, the rest of the world says L/100km. Same data, inverted scale. Here's the cheat sheet.

Ask ten experts and you will get twelve answers. The underlying math, thankfully, only has one. Americans say MPG, the rest of the world says L/100km. Same data, inverted scale. Here's the cheat sheet.

The conversion

L/100km = 235.214 / MPG (US gallons). 30 MPG ≈ 7.8 L/100km.

Why L/100km is better

Linear with fuel cost. Going from 5 to 10 L/100km doubles fuel; going from 50 to 25 MPG doesn't double it intuitively.

Imperial vs US gallon

UK gallon is 20% bigger. UK 40 MPG ≈ US 33 MPG. Always check which.

Pro tips

  • Real-world MPG runs 10–20% below sticker — EPA tests use perfect conditions.
  • EVs report MPGe — converts kWh to gallons of gasoline equivalent (33.7 kWh = 1 gallon).

Frequently asked questions

What about hybrids? City MPG is usually higher than highway — regenerative braking does the work.

Is 50 MPG realistic? Yes for hybrids; rare for pure ICE except subcompacts in city driving.

Bookmark the calculator linked above — you will need it more often than you think.

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