Fuel Economy Converter
To convert MPG (US) to L/100km, divide 235.215 by the MPG value. For example, 30 MPG = 235.215 ÷ 30 = 7.84 L/100km. To convert L/100km to MPG, divide 235.215 by the L/100km value. MPG (Imperial) is 1.201 times MPG (US). To convert MPG to km/L, multiply MPG (US) by 0.4251.
Convert between MPG (US), MPG (Imperial), L/100km, and km/L instantly. Bidirectional fuel economy converter with trip cost calculator, vehicle comparison mode, annual fuel cost estimator, and reference table of common vehicle fuel economies.
Fuel Economy Converter
How to Use
- 1
Enter a fuel economy value
Type a number in the value field on the Convert tab
- 2
Select the source unit
Choose MPG (US), MPG (Imperial), L/100km, or km/L
- 3
View all conversions
See the value converted to all four fuel economy units instantly
- 4
Calculate trip cost
Switch to Trip Cost tab, enter distance, fuel economy, and gas price to see total fuel cost
- 5
Compare two vehicles
Use the Compare tab to see side-by-side fuel cost differences between two vehicles
- 6
Estimate annual cost
Use the Annual Cost tab to estimate yearly fuel expenses based on driving habits
- 7
Browse reference vehicles
Check the Reference tab for common vehicle fuel economies with visual comparison bars
Frequently Asked Questions
- How do I convert MPG to L/100km?
- To convert MPG (US) to L/100km, divide 235.215 by the MPG value. Formula: L/100km = 235.215 ÷ MPG. For example, 30 MPG = 235.215 ÷ 30 = 7.84 L/100km. To convert L/100km to MPG, use the same formula in reverse: MPG = 235.215 ÷ L/100km. The relationship is inversely proportional — as one goes up, the other goes down.
- What is the difference between US MPG and Imperial MPG?
- US MPG and Imperial (UK) MPG differ because a US gallon (3.785 liters) is smaller than an Imperial gallon (4.546 liters). The same vehicle will have a higher Imperial MPG number: multiply US MPG by 1.201 to get Imperial MPG. For example, 30 US MPG = 36.03 Imperial MPG. Always check which system is being used when comparing fuel economy figures.
- How do I convert km/L to MPG?
- To convert km/L to MPG (US), multiply by 2.35215. For example, 15 km/L × 2.35215 = 35.28 MPG. To convert MPG to km/L, divide by 2.35215. km/L is commonly used in Japan, South Korea, and parts of South America. Like MPG, a higher km/L value means better fuel efficiency.
- What is good fuel economy for a car?
- Good fuel economy depends on vehicle type. For sedans, 30-40 MPG (5.9-7.8 L/100km) is good. For SUVs, 25-30 MPG (7.8-9.4 L/100km) is solid. Hybrids typically achieve 45-60 MPG (3.9-5.2 L/100km). Electric vehicles are rated in MPGe (miles per gallon equivalent), often 100-130+ MPGe. The US fleet average for 2024 models is about 26 MPG.
- Why does L/100km work inversely compared to MPG?
- MPG measures distance per unit of fuel (higher = better), while L/100km measures fuel per unit of distance (lower = better). This inverse relationship means improvements at low MPG save more fuel than at high MPG. Going from 10 to 20 MPG saves 5 gallons per 100 miles, but going from 30 to 40 MPG only saves 0.83 gallons — this is called the "MPG illusion."
- How do I estimate annual fuel costs from fuel economy?
- Divide your annual miles by your MPG to get gallons used, then multiply by gas price. Formula: Annual Cost = (Annual Miles ÷ MPG) × Gas Price. For 12,000 miles/year at 30 MPG with $3.50/gal: (12,000 ÷ 30) × $3.50 = $1,400/year. For metric: Annual Cost = (Annual km × L/100km ÷ 100) × Price per liter.