Fuel economy & trip cost calculator
Convert fuel-economy conventions without mixing up US and imperial gallons, then turn the result into trip fuel and cost.
Arithmetic estimate only. Actual consumption varies with vehicle, route, load, weather, traffic and driving. No live prices, tolls, emissions or route planning.
Included
- L/100 km, km/L, mpg US and mpg imperial
- Kilometres and miles
- Price per litre, US gallon or imperial gallon
- One-way and round-trip fuel and cost
Not included
- Live fuel prices, tolls or route planning
- Emissions, EV energy use or mixed fuels
- Vehicle, traffic, load, weather or driving-style effects
What this means
The calculator normalizes every economy value to litres per 100 kilometres using exact named conversion constants. US and imperial gallons are always labelled separately.
Trip mode converts the distance to kilometres and the price to a per-litre amount before calculating fuel used and cost.
Formula & worked example
litres needed = trip kilometres × L/100 km ÷ 100 trip cost = litres needed × price per litre
7.5 L/100 km over 100 km at $2 per litre
- Fuel needed
- 7.5 L
- Price
- $2 per litre
The estimated trip cost is $15.
How this calculation works
The calculation follows the formulas, definitions and assumptions explained on this page. The references below support the method and any stated boundaries.
Official sources
- NIST — SI conversion factors — Exact length and US/imperial volume conversion constants used by the calculator