Fuel Efficiency Converter — MPG to km/L, L/100km Free
Convert fuel efficiency units online free — miles per gallon (US and UK) to kilometers per liter, liters per 100km and more. Instant conversion, no sign-up required.
Last updated: June 2026
Fuel economy guide
- Very efficient car
- under 6 L/100km · over 39 MPG (US)
- Typical car
- 8–10 L/100km · 24–29 MPG (US)
- Thirsty SUV / truck
- 12+ L/100km · under 20 MPG (US)
About this tool
Compare fuel economy across any unit
Fuel economy is quoted differently around the world — miles per gallon in the US and UK, litres per 100 km across Europe, and kilometres per litre in much of Asia — which makes comparing cars from different markets surprisingly hard. This fuel efficiency converter translates between all of them at once, so you can line up a vehicle rated in US MPG against one rated in L/100km in a single glance.
The key subtlety is that these units are inversely related: MPG and km/L measure distance travelled per unit of fuel (higher is better), while L/100km measures fuel consumed per distance (lower is better). The converter handles this inversion correctly using the standard factor (L/100km = 235.215 ÷ US MPG), so you never have to remember which way the maths goes.
It also keeps US and UK MPG separate, since the imperial gallon is larger than the US gallon and produces a higher MPG number for the same real economy. A quick reference guide shows what counts as efficient, typical or thirsty. Whether you're shopping for an imported car, planning a road-trip budget or just curious how your vehicle compares, every figure is computed locally in your browser — instant, free and private.
How it works
Three quick steps — no account, nothing uploaded to a server.
Type a figure
Enter economy in MPG, L/100km or km/L.
See every unit
All the other units convert at the same instant.
Judge the economy
Use the guide to see if it's efficient or thirsty.
FAQ
Frequently asked questions
How do I convert MPG to L/100km?
They're inversely related, so the formula is L/100km = 235.215 ÷ MPG (US). For example, 30 US MPG is about 7.84 L/100km. A higher MPG means a lower L/100km — both describe better fuel economy. Just type into either box and the converter handles it.
Why is US MPG different from UK MPG?
Because the gallon differs. A US gallon is about 3.785 litres while a UK (imperial) gallon is about 4.546 litres, so the same car achieves a higher number in UK MPG than in US MPG. The converter lists both so you can compare specs from different markets correctly.
Is a higher or lower number better for fuel economy?
It depends on the unit. For MPG and km/L, higher is better (you travel further per unit of fuel). For L/100km, lower is better (you use less fuel per distance). The converter shows them together so you can read efficiency whichever way your country expresses it.
What counts as good fuel economy?
As a rough guide, under about 6 L/100km (over ~39 US MPG) is very efficient, 8–10 L/100km is typical for a family car, and 12 L/100km or more (under ~20 US MPG) is thirsty. Hybrids and small cars sit at the efficient end; large SUVs and trucks at the other.
How do I convert km/L to L/100km?
Divide 100 by the km/L figure: L/100km = 100 ÷ (km/L). So 12.5 km/L is 8 L/100km. The converter does this instantly, and also shows the equivalent in US and UK MPG for comparison with imported cars.
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