Transparent method
The formula
Worked example
Example inputs
How to interpret the result
Fuel cost is miles divided by fuel economy, times the price of a gallon. Driving 12,000 miles a year at 28 mpg burns about 429 gallons, and at $3.50 a gallon that is about $1,500 a year, or $125 a month. The number moves with the price in a steady way: each dollar on a gallon of gas adds about $429 a year in this example. It also shows why a better mileage rating matters more the further you drive.
Before you rely on it
What to check
Use your own annual miles and the mileage you really get, not the sticker figure. Commutes, cold weather and short trips lower real mileage.
The common error
Where people go wrong with fuel cost calculator
Estimating from the cost of a single fill-up. A tank size, a fuel price and a route all change between fill-ups, and the yearly total is a steadier guide.
Sensitivity evidence
How fuel price per gallon changes the estimated annual fuel cost
| Fuel price per gallon | Estimated annual fuel cost | Estimated monthly fuel cost |
|---|---|---|
| $2.80 | $1,200 | $100 |
| $3.15 | $1,350 | $113 |
| $3.50worked example | $1,500 | $125 |
| $3.85 | $1,650 | $138 |
| $4.20 | $1,800 | $150 |
Every input, tested
Which input moves the estimated annual fuel cost most
| Input | Tested from | To | Estimated annual fuel cost at each end | Swing |
|---|---|---|---|---|
| Fuel economy (MPG) | 25 | 31 | $1,680 to $1,355 | $325 (22%) |
| Annual miles driven | 10,800 | 13,200 | $1,350 to $1,650 | $300 (20%) |
| Fuel price per gallon | $3.15 | $3.85 | $1,350 to $1,650 | $300 (20%) |
Two variables at once
Estimated annual fuel cost by fuel price per gallon and annual miles driven
| Fuel price per gallon \ Annual miles driven | 9,600 | 12,000 | 14,400 |
|---|---|---|---|
| $2.80 | $960 | $1,200 | $1,440 |
| $3.15 | $1,080 | $1,350 | $1,620 |
| $3.50 | $1,200 | $1,500 | $1,800 |
| $3.85 | $1,320 | $1,650 | $1,980 |
| $4.20 | $1,440 | $1,800 | $2,160 |
Step by step
The worked example, input by input
| Input | Value used |
|---|---|
| Annual miles driven | 12,000 |
| Fuel economy (MPG) | 28 |
| Fuel price per gallon | $3.50 |
| Estimated annual fuel cost | $1,500 |
| Estimated monthly fuel cost | $125 |
Where the inputs come from
Annual miles driven is best taken from odometer readings over a year, or your service records. Fuel economy is your real-world miles per gallon, not the sticker figure, which you can compute by dividing miles by the gallons you put in over several tanks. Fuel price is the average price per gallon you pay, and it varies by region and season. For an electric or hybrid vehicle, use the EV-specific calculator.
When the result stops applying
City and highway mileage differ, so a mixed figure is an approximation. The cost of a longer commute includes wear and time, not only fuel. Diesel and premium fuel cost more per gallon.
What to compare it with
Compare gasoline and electric costs on the EV vs gas fuel savings calculator, and add all ownership costs with the vehicle total cost of ownership page. The trip cost calculator handles single trips. The unit conversion pages convert gallons, liters and kilometers if you use other units.
People also ask
Frequently asked questions
How do I calculate my real fuel economy?
Fill the tank, note the odometer, drive, then fill again and divide miles driven by the gallons added. Averaging several tanks gives a reliable figure.
Does the sticker mpg match real-world mileage?
Often not exactly. Driving style, speed, weather and load change it, and many drivers see somewhat lower figures than the label.
How much can I save by improving mpg?
Multiply annual miles by the price and the difference in fuel use. Going from 20 to 30 mpg at 12,000 miles saves about 200 gallons a year.