Work out what a road trip or a full year of driving costs in gas. Enter the distance, the fuel economy your car really gets and the price you pay per gallon. Results update as you type.
Some fields need a fix, so the result shows your last valid numbers.
- This trip
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- Gallons for this trip
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- Gallons per year
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- Per week
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How the fuel cost calculator works
The calculator divides the miles you drive by your car’s miles per gallon to find how many gallons you burn, then multiplies those gallons by the price per gallon. It runs that sum twice: once for the trip distance and once for your yearly mileage. The monthly and weekly figures are simply the yearly cost divided by 12 and by 52. Cost per mile is the gas price divided by your mpg, so it stays the same no matter how far you drive.
The formula in plain English
- Gallons used = miles ÷ mpg
- Fuel cost = gallons used × price per gallon
- Cost per mile = price per gallon ÷ mpg
Here is the default example worked through. At 12,000 miles a year and 30 mpg, the car uses 400 gallons. At $3.40 a gallon that comes to $1,360 a year, about $113 a month, or roughly 11 cents a mile. The default numbers are placeholders to show how the math works. They are not averages, so replace them with your own.
Getting accurate inputs
The result is only as good as the numbers you enter. Three tips help a lot:
- Use your real mpg. The window sticker is a lab figure. Your own number from a fill-up is better, and our MPG calculator works it out in a few seconds.
- Use your local gas price. Prices change by state, by station and by week. For a long trip, pick a price in the middle of what you expect to see along the route.
- Check your yearly miles. Compare two odometer readings a year apart, or look at the mileage on your last two service receipts.
Real-world mpg moves with how and where you drive. Highway cruising at a steady speed usually beats stop-and-go city traffic. Heavy loads, roof boxes, towing, cold weather, short trips and high speeds all lower it. If your trip mixes all of these, run the numbers with a slightly lower mpg to stay on the safe side.
How to use the result
Budget a trip. Use the trip figure as your fuel budget, then add a small cushion for detours, traffic and idling. Splitting gas with friends? Divide the trip cost by the number of people.
Compare two cars. Keep the miles and gas price the same and change only the mpg. The gap in yearly cost shows what better fuel economy is worth to you. Multiply it by the years you plan to keep the car to see whether a pricier, more efficient model pays for itself.
See the bigger picture. Fuel is only one part of what a car costs. Depreciation, insurance and maintenance often add up to more. The car ownership cost calculator puts all of them side by side.
A sudden drop in mpg can be an early sign of a problem, such as an engine misfire. If that comes with a flashing check engine light, get the car checked soon, because driving on a misfire wastes fuel and can damage the catalytic converter.
Frequently asked questions
How do I calculate fuel cost for a trip?
Divide the trip distance by your car’s mpg to get gallons, then multiply by the price per gallon. A 250-mile trip at 30 mpg uses about 8.3 gallons, which costs about $28 at $3.40 a gallon.
What is a good cost per mile for fuel?
It depends on your car and local prices, so compare against your own options rather than a single number. Cost per mile is the gas price divided by mpg, so either cheaper gas or better mpg lowers it.
Does this include tolls, parking or wear?
No. This calculator covers fuel only. For depreciation, insurance, maintenance and financing, use the car ownership cost calculator.
Are my numbers saved?
No. The math runs in your browser. Nothing you type is stored or sent to us.