The fuel cost of a trip is just three things multiplied together: how far you drive, how much fuel your car burns per mile, and what that fuel costs. Enter the distance, your MPG (or L/100km) and the price of gas, and this calculator shows the fuel you will need, the total cost, the cost per person if you are sharing the ride, and the cost per mile. Flip on round trip to cover the drive home too. Switch between US and Metric units to match how your car and pump prices are quoted.
mi
MPG
$/gal
km
L/100km
$/L
Fuel needed—for the trip
Total cost—
Cost per person—1 person
Cost per mile—per mile
How to Calculate the Gas Cost of a Trip
Distance, fuel economy and price — three inputs and you are done.
1
Enter the distance
Type how far you are driving in miles (or kilometres on the Metric tab), then set one way or round trip.
2
Add economy and price
Enter your car's MPG (or L/100km) and the current price of gas per gallon (or per litre).
3
Read the cost
See the fuel needed, total cost and cost per mile. Set people to split and get the cost each. On electric? Try the EV Charging Cost Calculator.
Frequently Asked Questions
How do I calculate the gas cost of a trip?
Three numbers give you the answer: the trip distance, how far your car goes on a unit of fuel, and the price of that fuel. In US units, divide the distance in miles by your MPG to get the gallons you will burn, then multiply the gallons by the price per gallon to get the total cost. In metric units, multiply the distance in kilometres by your L/100km and divide by 100 to get litres, then multiply by the price per litre. This calculator does that arithmetic instantly as you type, and it can double the distance for a round trip and divide the total between everyone sharing the ride. Everything runs in your browser, so nothing you enter is sent anywhere.
How much gas will I use for a given number of miles?
The gas you use is simply the distance divided by your fuel economy. For a 300-mile drive in a car that does 30 MPG, that is 300 ÷ 30 = 10 gallons; at 25 MPG the same drive needs 12 gallons, and at 40 MPG it needs 7.5. In metric terms a car rated at 8 L/100km uses 8 litres for every 100 kilometres, so a 300 km trip burns 24 litres. Enter your real distance, economy and price above and the Fuel needed box shows the exact gallons or litres for your trip — including the return leg if you switch to round trip. Notice how a small change in MPG moves the fuel figure: economy matters most on long drives.
What is the difference between MPG and L/100km?
They measure the same thing from opposite directions. MPG — miles per gallon, used in the US — counts distance per unit of fuel, so a bigger number is better. L/100km — litres per 100 kilometres, used across most of the world — counts fuel per fixed distance, so a smaller number is better. Because one is the inverse of the other, they do not convert with a simple multiplier: 30 MPG is about 7.8 L/100km, while 40 MPG is about 5.9. Use the US tab if your car and gas prices are quoted in miles, gallons and dollars per gallon, and the Metric tab if you think in kilometres, litres and price per litre. The trip cost comes out the same way in either system.
How should we split gas money on a road trip?
The simplest fair split is to divide the total fuel cost by the number of people in the car, which is what the People to split field does here — set it to how many are sharing and the Cost per person box updates instantly. Whether the driver pays a share is up to your group: some cover the driver in return for their car and wear-and-tear, others split evenly among everyone including the driver. For a there-and-back trip, switch to round trip first so the figure covers both legs, then divide. Tolls and parking are separate costs this calculator does not include, so add those on top if you are settling up at the end of the trip.
What are simple ways to lower the fuel cost of a trip?
Fuel cost falls when you improve any of the three inputs. Drive fewer miles by planning a direct route and combining errands; raise your effective MPG by easing off hard acceleration, keeping to steady highway speeds, removing roof boxes and heavy loads, and keeping tyres properly inflated; and pay less per gallon by filling up away from motorway and airport stations and using a fuel-price app to find the cheapest nearby pump. Sharing the ride does not cut the total fuel used, but splitting it between more people lowers what each person pays. Try changing the distance, MPG and price above one at a time to see which lever saves the most on your particular trip.