Fuel Efficiency Calculator — MPG, Free
Calculate US miles per gallon and litres per 100 kilometres from distance and fuel used. The worksheet interprets your fill-up record rather than looking up a vehicle’s certified economy.
- Runs in your browser
- Nothing is uploaded
- No signup; device limits apply
Numbers stay on your device. Nothing is sent to a server.
Next step
How to use this tool
Enter positive distance and fuel amounts and choose miles/kilometres and US gallons/litres. Similar tank-fill levels at the start and end make comparisons across periods more meaningful.
Results and examples
Travelling 100 km on five litres gives 5 L/100 km, approximately 47.04 US MPG. Lower L/100 km and higher MPG both mean less fuel consumed for the same distance.
Limitations
- US-gallon MPG differs from Imperial-gallon MPG.
- Odometer, pump and tank-fill uncertainty affect the result.
Fields
| Field | Guidance and constraints |
|---|---|
| Distance driven | Accepted range: 0.01–100000 · Input step: 0.1 |
| Fuel used | Accepted range: 0.01–10000 · Input step: 0.01 |
| Distance unit | Miles / Kilometres |
| Fuel unit | Gallons (US) / Litres |
Data handling
Processing stays in the current browser tab; the site does not upload tool input for the calculation itself.
Sources
Frequently asked questions
What is 5 L/100 km in MPG?
Travelling 100 km on five litres gives 5 L/100 km, approximately 47.04 US MPG. Lower L/100 km and higher MPG both mean less fuel consumed for the same distance.
Which direction indicates lower consumption?
US-gallon MPG differs from Imperial-gallon MPG. Odometer, pump and tank-fill uncertainty affect the result.
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