How to use
Enter the one-way distance, choose its unit and select whether to include a return journey. Enter fuel economy in L/100 km, km/L, MPG US or MPG UK. Choose the price unit independently: per litre, US gallon or Imperial gallon.
The independent selectors support cases such as British MPG with a pump price per litre. Enter one currency for the complete estimate. To share the cost, enter all payers, including the driver if the driver contributes.
Calculation method
Distance and fuel economy convert to a consistent fuel-per-distance basis. Fuel needed = total trip distance × fuel per distance. Cost = unrounded fuel quantity × price per matching volume unit. The return option doubles the entered one-way distance.
Unit switches retain the source physical values rather than repeatedly rounding converted inputs. The displayed total rounds once to cents. When sharing that rounded total, the tool divides whole cents and distributes any remainder one cent at a time, so the individual shares add to the total.
Worked example
For 500 km at 7.5 L/100 km, fuel needed is 500 × 7.5 / 100 = 37.5 L. At 1.50 per litre, cost is 56.25. A return journey over the same route doubles both quantities. In US units, 300 miles at 30 MPG US need ten US gallons; at 3.50 per US gallon the trip costs 35.00.
A total of 10.00 shared among three payers becomes 3.34, 3.33 and 3.33 rather than three shares that fail to add up.
Assumptions and exclusions
Fuel economy remains constant for the modeled distance. Traffic, speed, weather, load, idling and route changes are not inferred. Tolls, parking, accommodation and vehicle wear are excluded. US and Imperial gallons remain distinct. An entered zero price means free fuel; an empty price remains unknown. This tool does not estimate EV battery use.
Use the electricity calculator for compatible kWh-based scenarios, or the unit price calculator to compare prices per equal quantity.
For the measurement and planning details, read trip fuel costs: mpg, litres and shared payments.