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Gas cost calculator

Enter how far you're going, your car's fuel economy and the price of gas to see what the trip will cost. Make it a round trip, split it between passengers, or switch to liters and kilometers.

Units
Trip

Copy it from your maps app or trip planner. We don't look up routes, so the trip stays on your device.

Your own figure is best: the MPG calculator works it out from a fill-up. Otherwise use the highway rating on fueleconomy.gov for long drives.

The price at the pump where you'll fill up.

Everyone sharing the cost, including the driver.

Gas for the trip
$29.02
250 miles · 8.93 gallons at $3.25 a gallon

Trip breakdown

Distance driven
250 mi (402 km)
Fuel used
8.93 gal (33.8 L)
Cost per mile
$0.12
Cost per 100 miles
$11.61

28 MPG is 8.4 L/100 km.

What if…

Gas cost
$2.75/gal
$24.55
$3.25/gal
$29.02
$3.75/gal
$33.48
$4.25/gal
$37.95
Your car got
23 MPG
$35.33
28 MPG
$29.02
33 MPG
$24.62
38 MPG
$21.38
Real fuel use changes with speed, traffic, hills, load and weather. fueleconomy.gov notes that gas mileage usually drops quickly above 50 mph, so leave some margin for a fast highway trip.
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  • Free, no sign-up
  • Works on phone and desktop

How to work out the gas cost of a trip

  1. 1

    Enter the distance one way, copied from your maps app or trip planner. Choose Round trip to double it.

  2. 2

    Type your car's fuel economy in MPG, or switch to kilometers and liters for L/100 km or km/L.

  3. 3

    Add the price per gallon (or per liter) and the number of people splitting the cost.

  4. 4

    Read the trip cost, the gallons it takes and the cost per mile. What if shows the same trip at other prices and MPGs.

Features

  • One way or round trip

    Double the distance with one click and see how many gallons or liters the drive will burn.

  • Split it fairly

    Enter how many people share the ride to see what each person owes for gas, driver included.

  • MPG, L/100 km or km/L

    US units first, metric with one switch. What you typed is converted, so it stays the same trip.

  • What if gas goes up?

    See the cost if gas is 50 cents cheaper or a dollar dearer, or if your car gets 5 MPG more or less.

The formula, with examples

Gas cost comes down to two steps. First the fuel: distance ÷ MPG = gallons. Then the money: gallons × price per gallon = cost. In metric it's distance ÷ 100 × L/100 km = liters, then liters × price per liter.

  • A weekend away: 180 miles each way is a 360-mile round trip. At 30 MPG that's 12 gallons, and at $3.25 a gallon $39.00, or $19.50 each for two people.
  • Coast to coast: about 2,800 miles in an SUV that gets 24 MPG on the highway burns 117 gallons. At $3.40 a gallon the fuel comes to $396.67, or $0.14 a mile.
  • In metric: 450 km in a car using 7.2 L/100 km takes 32.4 liters. At 1.65 a liter that's 53.46 in your currency.

Cost per 100 miles

The quickest way to compare cars or prices is the cost of driving 100 miles:

Fuel economyAt $3.00At $3.50At $4.00
20 MPG (11.8 L/100 km)$15.00$17.50$20.00
25 MPG (9.4 L/100 km)$12.00$14.00$16.00
30 MPG (7.8 L/100 km)$10.00$11.67$13.33
40 MPG (5.9 L/100 km)$7.50$8.75$10.00
50 MPG (4.7 L/100 km)$6.00$7.00$8.00

Going from 20 to 30 MPG saves more per mile than going from 40 to 50, even though both are 10 MPG better. Fuel used falls off as MPG rises, which is why much of the world measures economy as fuel per distance (L/100 km) instead.

Getting a realistic MPG for your trip

The cost is only as good as the fuel economy you type in. Your own number from a few full-tank fill-ups beats any rating, and the MPG calculator works it out for you. A trip computer is a good second choice. If the car is new to you, look up its EPA highway rating on the window sticker or on fueleconomy.gov.

Then think about how you'll drive. According to fueleconomy.gov, aggressive driving (speeding, hard acceleration and braking) can lower gas mileage by roughly 15% to 30% at highway speeds, and gas mileage usually drops quickly above 50 mph. A roof box, a full load of people and luggage, towing and running the air conditioning hard all cost fuel too, so for a fast or heavily loaded trip, budget for a lower MPG than you usually see.

Converting fuel economy

To turn MPG into liters per 100 km, divide 235.2 by the MPG: 30 MPG is about 7.8 L/100 km. The same division turns L/100 km back into MPG. For kilometers per liter, multiply MPG by 0.425. UK figures use the larger imperial gallon, so UK MPG is about 20% higher than US MPG for the same car: 36 UK MPG is about 30 US MPG.

Planning more than fuel? A different tire size changes how far your odometer thinks you went: the tire size calculator shows by how much. For projects at home, try the concrete calculator or the BTU calculator.

Frequently asked questions

How do I calculate the gas cost of a trip?

Divide the distance by your car's MPG to get the gallons, then multiply by the price per gallon. A 300-mile drive at 25 MPG uses 12 gallons; at $3.50 a gallon that's $42.00.

How much gas does it take to drive 100 miles?

100 divided by your MPG. A 25 MPG car uses 4 gallons, a 35 MPG car about 2.9 gallons and a 50 MPG hybrid 2 gallons. In metric it is already in the figure: a car rated at 7 L/100 km uses 7 liters every 100 km.

Which MPG should I use for a road trip?

Your own figure is best: work it out from a couple of fill-ups with the MPG calculator. Otherwise use the highway rating from the window sticker or fueleconomy.gov. Expect less at 75 or 80 mph: fueleconomy.gov notes that gas mileage usually drops quickly above 50 mph.

How do we split gas money between friends?

Divide the total by everyone in the car, driver included, which is what the calculator does. Some groups let the driver pay less because they're also covering wear on the car, tolls or parking. Agree before you leave.

Is a round trip exactly double?

Close to it if you take the same route both ways. Climbs on the way out are partly paid back by descents on the way home, but traffic, wind, speed and gas prices along the route can make the two legs differ a little.

Does this include tolls, parking or wear and tear?

No, only fuel. Running a car also costs tires, oil, repairs, insurance and depreciation. That is why the IRS standard mileage rate for business driving is much higher than the fuel cost per mile.

Is my trip sent anywhere?

No. You type the distance yourself and everything is calculated in your browser. The calculator doesn't look up routes or your location. If you copy the link, the numbers are stored in the link itself.

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