Fuel Cost Calculator
Enter the distance and your car’s fuel economy. If it is a commute rather than a one-off, set how many times a week you make it and the calculator will show you the annual total — which is usually the number that changes people’s minds.
Your inputs
Your result
Formula
How fuel cost is worked out
The calculation is short: divide the distance by your fuel economy to get the fuel used, then multiply by the price. In metric the shape is the same — consumption per hundred kilometres, scaled to the distance, times the price per litre.
The part people get wrong is the fuel economy figure. The number on the window sticker is a laboratory result. Real-world economy is usually worse, and how much worse depends on how you drive: short trips from cold, heavy traffic, roof boxes, underinflated tyres and sustained high speeds all cost you several miles per gallon each. If your car has a long-term average readout, use that instead of the official figure.
Why the annual number is the useful one
A commute that costs six dollars a day feels trivial. The same commute is well over a thousand dollars a year, which is a different kind of decision — it is comparable to a transit pass, to the price difference between two cars, or to living slightly closer to work.
Fuel is only part of what a mile costs
Every mile you drive also consumes tyres, servicing intervals, and some resale value. Fuel is typically only a third to a half of the true marginal cost of driving. If you are comparing driving against another option, the total cost per mile is the fairer comparison.
Frequently asked questions
How do I convert MPG to litres per 100 km?
For US MPG, divide 235.2 by the MPG figure. So 28 MPG is about 8.4 L/100 km. UK gallons are larger, so for imperial MPG divide 282.5 instead.
Does driving slower actually save fuel?
Above roughly 50 mph, aerodynamic drag dominates and rises with the square of speed, so yes, holding a lower cruising speed measurably improves economy. Below that, steady throttle and avoiding hard acceleration matter more than the speed itself.
Does air conditioning use much fuel?
It costs a few percent in most conditions. At low speeds it can be worse than opening the windows; at highway speeds the extra drag from open windows generally costs more than the compressor does.
Is premium fuel worth it?
Only if the manufacturer requires it. In an engine designed for regular fuel, higher octane delivers no extra economy or power, so the price difference is simply lost.