Fuel Cost Calculator
Pick US / Imperial, Metric or Electric. In US / Imperial you enter the distance in miles, the fuel economy in MPG and the price per gallon. In Metric you enter kilometers, the economy in liters per 100 km or km per liter, and the price per liter. In Electric you pick kWh/100 mi, mi/kWh, kWh/100 km or km/kWh, then enter the distance, the efficiency and the price per kWh. Press Calculate to see the fuel or electricity the trip uses, the total cost and the cost per 100 miles or 100 km. Fuel and kWh are shown to 2 decimal places and costs to the cent, with a $ sign whatever currency you price it in.
How to use the Fuel Cost Calculator
- Enter your numbers in the Fuel Cost Calculator above.
- Press the Calculate button to see the result.
- To try other numbers, change any value and press the button again.
The fuel cost formula
Fuel = Distance ÷ MPG · · · Metric: Fuel = Distance ÷ 100 × L/100 km, or Distance ÷ km/L · · · Electric: kWh = Distance ÷ 100 × kWh/100, or Distance ÷ mi/kWh · · · Cost = Fuel or kWh × Price
The cost per 100 miles is 100 ÷ MPG × price, and the cost per 100 km is L/100 km × price, or 100 ÷ km/L × price. Electric works the same way, with kWh in place of liters. A charging loss of L% divides the kWh by (1 − L/100), because that share of what the wall supplies never reaches the battery. The calculator works with the numbers exactly as you type them and rounds each figure once, at the end.
Worked example
A 500-mile trip at 28 MPG with gas at $4.20 a gallon uses 17.86 gallons and costs $75.00, because 500 ÷ 28 × 4.20 is exactly 75. The cost per 100 miles is $15.00. Rounding the gallons to 17.86 first would give $75.01, so the calculator keeps the full figure until the end. In Metric, 400 km at 6.5 L/100 km with fuel at 1.80 a liter uses 26 liters and costs 46.80, or 11.70 per 100 km. At 15 km per liter the same trip uses 26.67 liters and costs 48.00, or 12.00 per 100 km. In Electric, a 300-mile trip at 30 kWh/100 mi with power at $0.16 per kWh uses 90 kWh and costs $14.40, or $4.80 per 100 miles. With a 16% charging loss it takes 107.14 kWh from the wall and costs $17.14. Those prices are examples, so enter your own.
Frequently asked questions
Which fuel economy figure should I enter?
The calculator applies one figure to the whole distance. If you know what your car does on the kind of roads this trip covers, enter that figure rather than a general rating.
Can I use UK miles per gallon?
Yes, if the price is per imperial gallon too. The calculator divides the miles by your MPG, so the fuel comes out in whichever gallon your MPG uses. US MPG with a price per imperial gallon, or the other way round, gives a wrong cost.
Can I enter kilometers per liter?
Yes. In Metric, set the fuel economy unit to km per liter. The cost comes out the same as the matching L/100 km figure, because 20 km/L is 5 L/100 km.
How do I work out an EV trip cost?
Pick Electric, choose the unit your car reports and enter the distance, the efficiency and your price per kWh. Use the price you will pay on this trip. The EPA label gives kWh per 100 miles, which it calls an estimated rate of consumption, and it relates directly to the cost.
What is the charging loss field?
Some of the power from the wall never reaches the battery. The US Department of Energy puts that loss at about 16%, and fueleconomy.gov says it varies with the vehicle, the charging system, the state of the battery and the weather. Leave the field empty unless you know your efficiency figure leaves that loss out, or you would count it twice. Ask your carmaker if you are unsure what your display measures.