How to calculate your gas mileage (MPG)
Fill your tank and reset your trip meter. Drive as usual, then fill up again and note how many gallons it took. Divide the miles you drove by those gallons.
MPG = Miles driven ÷ Gallons used
Cost per mile = Price per gallon ÷ MPG
Example
If you drove 350 miles and it took 12.5 gallons to refill, your car gets 28 MPG. At $3.25 a gallon, each mile costs about 12 cents. Driving 1,000 miles a month costs about $116 in gas. That's 8.4 liters per 100 km.
Measure over two or three fill-ups for the most accurate number, since a single tank can vary with traffic, weather and air conditioning.
2026 IRS standard mileage rates
If you drive your own car for work, you can use the IRS standard mileage rate to deduct your costs (if you're self-employed) or as the benchmark for employer reimbursement. In 2026 the IRS made a rare mid-year change because of higher fuel prices, so there are two rates this year.
| Purpose | Jan 1 – Jun 30 | Jul 1 – Dec 31 |
|---|---|---|
| Business | 72.5¢ per mile | 76¢ per mile |
| Medical or military moving | 20.5¢ per mile | 23.5¢ per mile |
| Charity | 14¢ per mile | 14¢ per mile |
For example, 4,000 business miles in the first half of the year and 5,000 in the second half are worth $2,900 + $3,800 = $6,700.
Keep a mileage log
The IRS expects a record of each business trip: the date, where you went, the purpose and the miles driven. Commuting from home to a regular workplace doesn't count as business mileage.
Ways to get better mileage
- Keep tires at the recommended pressure, printed inside the driver's door.
- Accelerate gently and use cruise control on highways.
- Remove roof racks and extra weight when you don't need them.
- Keep up with oil changes and air filter replacements.
Common questions
How do I calculate my car's MPG?
Divide the miles you drove since your last fill-up by the gallons it took to refill the tank. For example, 350 miles ÷ 12.5 gallons = 28 MPG.
What is the IRS mileage rate for 2026?
For business driving it is 72.5 cents per mile from January 1 to June 30, and 76 cents per mile from July 1 to December 31. Medical and military moving miles are 20.5 cents, then 23.5 cents. Charity miles are 14 cents.
Do employers have to reimburse mileage at the IRS rate?
Not under federal law, although many do. A few states, such as California, require employers to reimburse necessary work expenses. Reimbursement above the IRS rate may count as taxable income.
What is a good MPG?
Many new gas cars get 25–35 MPG combined, and hybrids often get 45–55 MPG. Trucks and large SUVs usually get less than 25 MPG.
More calculators
- Trip fuel costRoad trip cost, gas vs electric
- Car loan calculatorMonthly payment with tax, fees and trade-in
- Self-employment taxSocial Security and Medicare on 1099 income
Last updated .