Fuel Economy Calculator
Enter fuel filled and distance driven to get L/100km, km/L and US/UK MPG.
Input Data
Results
At a glance:Fuel economy is derived from fuel volume and distance. L/100km = (fuel ÷ distance) × 100; km/L = distance ÷ fuel; MPG (US) = 235.215 ÷ L/100km; MPG (UK) = 282.481 ÷ L/100km (US gal 3.785 L, UK gal 4.546 L, 1 mile = 1.609 km).
Formula
L/100km = (fuel ÷ distance) × 100.
km/L = distance ÷ fuel.
MPG (US) = 235.215 ÷ L/100km; MPG (UK) = 282.481 ÷ L/100km.
How to Use
- Enter the fuel volume added (L).
- Enter the distance driven since the last fill (km).
- The tool returns L/100km, km/L and US/UK MPG.
Case Studies
40 L / 500 km
L/100km = (40/500)×100 = 8.0.
km/L = 12.5; MPG (US) = 235.215/8 ≈ 29.4.
FAQ
Is lower L/100km always better?
Yes — it means less fuel per 100 km, i.e. more efficient. This is the inverse of km/L and MPG, where higher is better.
US vs UK MPG — which is bigger?
They use different gallon sizes (US 3.785 L, UK 4.546 L), so the same car shows a larger number in UK MPG. US cars use US MPG.
How to estimate fuel cost from this?
consumption × distance ÷ 100 × price = cost. E.g. 8 L/100km × 1000 km ÷ 100 × $18/L = $1,440.
Highway vs city?
Frequent stop-and-go in the city raises consumption; highway cruising is lower. The same car can differ 20–40% in L/100km — better to measure separately.
How to compare an EV?
An EV uses kWh/100km, conceptually the same as L/100km (energy per 100 km); you can compare energy costs directly.
Relation to speed?
Consumption is optimal around 80–90 km/h; much faster and air drag pushes it up. Pair with a speed calculator for a fuller picture.
Related Tools
References
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.