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MPG to L/100 km: how to convert fuel economy (US and Imperial gallons)
Convert miles per gallon to litres per 100 km and back, understand why US and Imperial MPG differ, and compare cars from Canada and the USA correctly.
Updated 2026-10-08 · 2 min read
Shopping across the border means comparing fuel economy in two different systems. US window stickers and listings use miles per gallon (MPG); Canadian EnerGuide labels and Natural Resources Canada use litres per 100 kilometres (L/100 km). To make it more confusing, older Canadian and UK sources quote MPG in Imperial gallons, which are about 20% larger than US gallons.
Use our fuel economy converter for instant answers, or the formulas below.
The formulas
| From | To | Formula |
|---|---|---|
| US MPG | L/100 km | 235.215 ÷ MPG |
| Imperial MPG | L/100 km | 282.481 ÷ MPG |
| L/100 km | US MPG | 235.215 ÷ L/100 km |
| L/100 km | km/L | 100 ÷ L/100 km |
Where the numbers come from: one mile is 1.609344 km, a US gallon is 3.785 litres and an Imperial gallon is 4.546 litres.
Quick conversion table
| US MPG | L/100 km | Same car in Imperial MPG |
|---|---|---|
| 20 | 11.8 | 24.0 |
| 25 | 9.4 | 30.0 |
| 30 | 7.8 | 36.0 |
| 35 | 6.7 | 42.0 |
| 40 | 5.9 | 48.0 |
| 45 | 5.2 | 54.0 |
| 50 | 4.7 | 60.0 |
Lower is better for L/100 km
MPG measures distance per fuel — higher is better. L/100 km measures fuel per distance — lower is better.
L/100 km is actually the more useful number for budgeting, because fuel cost scales directly with it. Going from 12 to 10 L/100 km saves 2 litres every 100 km. In MPG terms, the same improvement looks like 19.6 → 23.5 MPG, and a much bigger-looking jump from 40 to 50 MPG saves only about 1.2 L/100 km. This "MPG illusion" is why upgrading from a thirsty vehicle to an average one saves more money than upgrading from an efficient one to a very efficient one.
Comparing official ratings across the border
US ratings come from the EPA (fueleconomy.gov) and Canadian ratings from Natural Resources Canada's Fuel Consumption Guide. Both use similar 5-cycle test methods, so after converting units the figures are usually close, but not always identical — the two agencies round and publish differently.
Every listing and research page on this site shows EPA ratings in both L/100 km and US MPG, so you can compare without converting by hand.
Electric and plug-in vehicles
EVs are rated in MPGe in the US — the distance an EV travels on the energy content of one US gallon of gasoline (33.7 kWh). Canada shows the equivalent as Le/100 km, plus electricity use in kWh/100 km. For running costs, kWh/100 km multiplied by your electricity rate is the number that matters.
Estimate your yearly fuel cost
Fuel cost per year = (km driven ÷ 100) × L/100 km × price per litre. At 20,000 km a year, $1.60/L and 8 L/100 km, that's 200 × 8 × 1.60 = $2,560 a year. Try your own numbers with our fuel cost calculator.
This guide is general information, not legal or tax advice. Rules and fees change — confirm the details with the official sources linked above before you buy or sell.