Gas Calculator: Trip Gas Cost in Miles and MPG
Work out how much gas a road trip needs and what it costs from the miles, your car's MPG and the price per gallon. Add a round trip and split the cost between friends.
Enter the distance, fuel economy and fuel price to see the trip cost.
This page does not look up fuel prices: type the price you pay, in any currency. The result is an estimate; real fuel use depends on driving conditions, speed, load and traffic.
About the Gas Calculator
The Gas Calculator works out how much gas a road trip will take and what it will cost. It opens in US units: the distance in miles, your car's fuel economy in miles per gallon (US) and the price per US gallon. Type the three numbers and the gallons and the gas cost appear at once. Tick Round trip if you are coming back the same way, and type the number of people in the car to see what each one owes.
You type the gas price yourself; the page does not look up prices at nearby stations. Check a price app or the sign at the pump and type that figure. The result is an estimate. How much gas you really burn depends on driving conditions: highway speed, stop-and-go traffic, air conditioning, a roof box, towing and hills can all move your MPG well away from the window-sticker figure.
How to use it
Plan the trip
- Type the trip length in miles. A map app gives you the driving distance.
- Type your car's combined MPG. The EPA rating is on the window sticker and at fueleconomy.gov, but your own average from the trip computer is more realistic.
- Type the price per gallon.
Share the cost
Tick Round trip to double the miles, and type how many people are splitting the gas money. Each share is rounded to the cent.
You can still switch any unit, for example to litres or to UK gallons if you are driving abroad.
The formula
For a round trip the miles are doubled first, and each person's share is the gas cost divided by the number of people.
Worked examples
- A 300-mile trip at 30 MPG and 3.50 a gallon. 300 ÷ 30 = 10.00 gallons, which cost 10 × 3.50 = 35.00.
- The same trip there and back with four friends. 600 miles need 20.00 gallons, which cost 70.00, so each person pays 17.50.
- Split three ways. 35.00 ÷ 3 = 11.67 each.
- A 1,000-mile trip in a 22 MPG SUV at 3.80 a gallon. 1,000 ÷ 22 = 45.45 gallons, which cost about 172.73.
Saving gas on a road trip
Keep the tyres at the pressure on the door sticker, drive at a steady speed with cruise control, and take roof racks off when you do not need them. Most cars use noticeably more gas above about 60 mph, so slowing down a little on the highway is the cheapest way to raise your MPG.
Privacy
Nothing is uploaded; every calculation runs in your browser and never leaves your device.
Related tools
Convert MPG to L/100 km with the Fuel Economy Converter, or switch to metric units on the full Fuel Cost Calculator.
Frequently asked questions
How much gas will my trip use?
Divide the trip miles by your car's MPG. A 300-mile trip in a car that gets 30 MPG uses 10 gallons. Tick round trip to double the miles for the drive home.
How do I calculate gas money for a road trip?
Multiply the gallons needed by the price per gallon, then divide by the number of people sharing the ride. The calculator rounds each share to the cent for you.
Which MPG figure should I use?
Use your own average from the trip computer if you have one. Otherwise use the combined EPA figure, which mixes city and highway driving, rather than the higher highway number.
Does the gas calculator use live gas prices?
No. Type the price per gallon from a price app or the pump sign. The result is an estimate that depends on that price and on how you drive.
Can I use it for a trip in Canada or Europe?
Yes. Switch the distance to kilometres, the economy to L/100 km and the price to per litre, and the calculator converts everything exactly.