The three ways fuel efficiency is measured
Which one you'll see depends on where you are: km/L and L/100km are both common outside North America (L/100km is the default on most European and Australian spec sheets), while the US and a few other countries use miles per gallon.
| Unit | Formula | Note |
|---|---|---|
| km/L (kilometres per litre) | Distance (km) ÷ Fuel used (L) | Higher is better. Most common outside North America. |
| L/100km (litres per 100km) | (Fuel used (L) ÷ Distance (km)) × 100 | Lower is better. The default on most European and Australian car spec sheets. |
| MPG (US, miles per gallon) | Distance (miles) ÷ Fuel used (US gallons) | Higher is better. Standard in the US - a US gallon (3.785L) is smaller than a UK gallon. |
Worked example
Say you drove 480km since your last fill-up, and it took 38.5L to top the tank back up:
km/L
12.47
480 ÷ 38.5
L/100km
8.02
(38.5 ÷ 480) × 100
MPG (US)
29.33
12.47 × 2.352
Converting between units
You only need one figure - km/L, L/100km or MPG - to get the other two:
- km/L → L/100km: divide 100 by the km/L figure.
- L/100km → km/L: divide 100 by the L/100km figure (same formula, either direction).
- km/L → MPG (US): multiply by 2.352.
- MPG (US) → L/100km: divide 235.21 by the MPG figure.
What's a good fuel efficiency?
There's no single "good" number - a small hatchback and a mid-size SUV shouldn't be judged the same way. As a rough guide by vehicle type:
| Vehicle type | km/L | L/100km | MPG (US) |
|---|---|---|---|
| Small hatchback / city car | 15-18 km/L | 5.5-6.5 L/100km | ~35-42 MPG |
| Mid-size sedan | 12-15 km/L | 6.5-8 L/100km | ~28-35 MPG |
| SUV / crossover | 8-11 km/L | 9-12 L/100km | ~19-27 MPG |
| Diesel mid-size | 14-18 km/L | 5.5-7 L/100km | ~33-42 MPG |
| Hybrid | 20-25+ km/L | 4-5 L/100km | ~47-59 MPG |
Typical ranges for real-world driving - actual figures vary by engine, driving style and conditions.
Skip the maths
Log a fill-up and Fuelwise calculates every unit automatically.
Frequently asked questions
How do I calculate km/L?
Divide the distance you drove (in kilometres) by the litres of fuel it took to refill the tank. 480km on 38.5L, for example, is 480 ÷ 38.5 = 12.47 km/L.
How do I convert L/100km to km/L?
Divide 100 by the L/100km figure. A car rated at 8 L/100km gets 100 ÷ 8 = 12.5 km/L. The same formula works in reverse: 100 ÷ (km/L) = L/100km.
How do I convert MPG to L/100km?
For US MPG: L/100km = 235.21 ÷ MPG. A car rated at 40 US MPG uses roughly 235.21 ÷ 40 ≈ 5.88 L/100km. UK (imperial) MPG uses a different gallon size, so it needs its own conversion (282.48 ÷ MPG).
What is a good fuel efficiency for a car?
It depends on the vehicle type - a small hatchback and a mid-size SUV shouldn't be judged by the same number. As a rough guide: small cars typically manage 15-18 km/L, mid-size sedans 12-15 km/L, SUVs 8-11 km/L, and hybrids 20-25+ km/L.
Once you know your number, the next question is usually: how do I improve it? Read our guide to improving fuel economy →