Fuel Cost Calculator
Estimate the fuel cost of a trip from distance, fuel economy and fuel price.
Written by Rahman · Last reviewed
Quick answer
Fuel needed is distance ÷ fuel economy, and the cost is that multiplied by the price per litre or gallon. The unit matters and the two common ones run in opposite directions: with miles per gallon a higher number is better, while with litres per 100 km a lower number is better.
Results are estimates for general guidance only. Double-check any figure you rely on for an important decision.
About the Fuel Cost Calculator
Fuel is one of the largest running costs of any vehicle. Estimating the cost of a journey in advance helps with budgeting, comparing routes and deciding whether to drive or take other transport.
This calculator works out the fuel a trip needs from the distance and your vehicle's fuel economy, then multiplies it by the fuel price.
Fuel needed = Distance ÷ Fuel economy Cost = Fuel needed × Price per unit
Fuel is a minority of what driving costs
This calculator answers what the fuel for a journey costs, which is the visible expense and rarely the largest one. Running a vehicle also consumes depreciation, insurance, tax, servicing, tyres and eventual repairs, and those accrue with time and distance whether or not you notice them at the pump.
The distinction matters when the calculation is being used to make a decision. Comparing driving against a train fare on fuel alone flatters the car, because the fare covers the operator's entire cost base while the fuel figure covers only part of yours.
- Depreciation is usually the single largest cost of a newer vehicle and is invisible until it is sold.
- Tyres and servicing scale with distance, so a per-mile allowance for them belongs alongside the fuel figure.
- Official mileage reimbursement rates exist precisely because they approximate total cost per mile rather than fuel cost per mile, which is why they sit well above the fuel figure.
Rated economy and real economy are different numbers
The economy figure entered here is usually the manufacturer's rating, measured under a standardised test cycle. Real driving departs from that cycle in ways that consistently reduce efficiency rather than averaging out.
Short journeys are the worst case, because a cold engine runs rich until it reaches operating temperature, so a two-mile trip can consume far more per mile than a long one. Speed matters too: aerodynamic drag rises with the square of velocity, so motorway cruising at higher speeds costs disproportionately more.
- Load, roof boxes, under-inflated tyres, air conditioning and stop-start traffic all reduce economy measurably.
- Cold weather lowers efficiency for combustion and electric vehicles alike, often substantially.
- For a realistic estimate, use your own observed economy from fill-up to fill-up rather than the published figure.
Frequently Asked Questions
What fuel economy figure should I use?
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Use your vehicle’s real-world economy if you know it, as it is usually lower than the official rating, especially in city driving.
Does driving style affect fuel cost?
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Yes. Hard acceleration, high speeds, heavy loads and idling all reduce fuel economy and increase the cost of a trip.
Can I use this for a round trip?
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Yes. Simply enter the total distance for the whole journey, including the return leg.
Why does my actual cost differ?
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Traffic, terrain, weather, air conditioning and fuel price changes all cause real costs to vary from any estimate.