Fuel Economy Converter

Convert MPG (US/UK), L/100km, and km/L with tank range and fuel cost calculator.

Click any card to use that unit as input.

MPG (US)
US gallon = 3.785 L
MPG (UK/Imperial)
UK gallon = 4.546 L
L/100km
Lower = more efficient
km/L
Higher = more efficient
Fuel Cost Calculator

Enter a fuel economy value above first.

Reference Values
Vehicle type L/100km MPG (US) MPG (UK) km/L
Very efficient (hybrid) 4.0 58.8 70.6 25.0
Efficient (compact car) 6.0 39.2 47.1 16.7
Average (mid-size sedan) 8.5 27.7 33.3 11.8
Large SUV / truck 13.0 18.1 21.7 7.7
Performance car 16.0 14.7 17.7 6.3
Conversion Formulas
MPG (US) = 235.215 ÷ L/100km
MPG (UK) = 282.481 ÷ L/100km
km/L = 100 ÷ L/100km
MPG (UK) ≈ MPG (US) × 1.20095

Frequently Asked Questions

What is the difference between US MPG and UK MPG?

US and UK miles are identical (1609.34m), but the gallon differs. A US gallon = 3.785 litres; a UK (Imperial) gallon = 4.546 litres. UK MPG figures are therefore ~20% higher than US MPG for the same vehicle. A car rated 35 US MPG = 42 UK MPG.

How do I convert L/100km to MPG?

To US MPG: divide 235.215 by the L/100km value. To UK MPG: divide 282.481 by the L/100km value. Examples: 7 L/100km = 33.6 US MPG or 40.4 UK MPG. 10 L/100km = 23.5 US MPG or 28.2 UK MPG.

Is lower L/100km always better?

Yes for fuel efficiency. L/100km measures litres consumed per 100 km of travel — lower means more efficient. A fuel-efficient petrol car achieves 5–7 L/100km; a hybrid 3–5; a large SUV 10–15. MPG is the inverse — higher is better. The two systems measure the same thing from different directions.

How do I calculate how much a road trip will cost in fuel?

Trip cost = (trip distance ÷ 100) × fuel consumption (L/100km) × fuel price per litre. For example, 500 km trip in a car using 8 L/100km with fuel at $1.80/L: (500 ÷ 100) × 8 × $1.80 = 5 × 8 × $1.80 = $72. This calculator's cost estimator does this automatically.