Calculate fuel mileage (MPG / km per litre), trip fuel cost and cost per mile from distance and fuel used.
MPG (US)
How to use this tool
Use the distance you actually travelled and the fuel it took to refill the tank — a full-to-full fill gives the truest figure.
Pick miles or kilometres and US gallons, UK gallons or litres; the calculator converts between all of them.
With a price it also shows cost per mile and the fuel cost of a planned trip.
Compare the same unit (MPG US vs UK differ) and similar driving — city and highway mileage are not the same.
Formula & worked example
300 miles on 10 US gallons = 30 MPG (US), 12.75 km/L, 7.84 L/100 km. At $3.50 per gallon the trip cost $35.00, or $0.117 per mile.
Limitations — read this before you rely on it
Real mileage varies with speed, load, tyres, weather and driving style, so a single tank is a snapshot — average over several tanks for a reliable figure. This calculator measures fuel economy, not a tax mileage reimbursement rate, which is a different figure set by employers and tax authorities.
Frequently asked questions
It depends on the vehicle: 30+ MPG (US) is good for a petrol car, while hybrids and small diesels can exceed 50 MPG. Compare within the same vehicle class.
The UK (imperial) gallon is 4.546 litres versus 3.785 litres for the US gallon, so the same car shows a higher UK MPG number.
Fill the tank, reset the trip meter, drive, then refill to full. Divide the trip distance by the fuel added at the second fill.
Litres used per 100 kilometres — lower is better, the opposite direction from MPG. 7.84 L/100 km equals 30 MPG (US).
No. Reimbursement rates (for example IRS standard mileage) are fixed allowances per mile and are separate from your car’s fuel economy.