How to Calculate Cost per Mile

Your monthly car payment tells you very little about what driving actually costs. Cost per mile does: it takes every dollar the car consumes, from fuel to depreciation, and divides it by the miles you drive. Once you know your number, you can compare cars, price a commute, decide whether a second car is worth keeping, and spot when an old car has started costing more than it should.

The math is simple:

Cost per mile = total cost of owning and running the car ÷ miles driven, over the same period.

Use a full year if you can. Shorter windows get distorted by one-off bills (a set of tires, an insurance renewal) landing inside them. If you only have three months of data, annualize carefully and add in the large items you know are coming.

The hard part is not the division. It is deciding what goes into "total cost" and getting honest numbers for it.

Every car expense falls into one of two buckets. Splitting them matters, because they behave differently when your mileage changes.

Two consequences follow from this split:

• Low-mileage drivers have a high cost per mile, because fixed costs are spread over fewer miles. A car that sits most of the week can easily cost more per mile than one used for a long daily commute.
• For a single extra trip, only variable costs matter. If you already own the car and pay its insurance, the marginal cost of driving 200 more miles is mostly fuel plus a little wear. This is the number to use when comparing driving against a train ticket or a flight.

Fuel or charging

Divide your fuel price by your real-world MPG. At $3.50 per gallon and 30 MPG, fuel costs about 11.7 cents per mile. Use your measured MPG, not the window sticker; our MPG calculator works it out from fill-ups. For an EV, multiply your electricity rate by the car's kWh per mile (the EPA label lists kWh/100 miles; divide by 100) and add a bit for charging losses and any public fast charging you pay for.

Depreciation

For most newer cars this is the largest single cost, and the easiest to forget because no bill arrives. Estimate it as purchase price minus what you expect the car to be worth when you sell it, divided by the years you will own it. Our depreciation calculator lets you set your own rate. Older cars depreciate slowly in dollar terms, which is a big reason a paid-off older car can be cheap per mile even with higher repair bills.

Insurance

Use your actual annual premium. It is mostly fixed, though some insurers price by mileage band, and usage-based programs can change it.

Maintenance and repairs

Add up oil changes, tire rotations, filters, brakes, fluids and repairs over the year. Tires deserve their own line: divide the cost of a set by its expected life in miles. A $900 set that lasts 50,000 miles costs 1.8 cents per mile. See average car maintenance cost for typical service price ranges.

Registration, taxes and fees

Annual registration, any personal property tax on vehicles in your state, inspection fees and, for EVs in many states, an annual EV fee. Check your state's DMV for the exact amounts.

Financing

Count the interest portion of loan payments, not the full payment. The principal is you buying the asset, and that cost is already captured by depreciation. Counting both double-counts the car.

Parking, tolls and washes

Easy to leave out, and in a city they can rival fuel. Include a monthly garage spot or permit if you pay it because you own the car.

Here is a sample calculation. Every figure is an illustrative assumption, not an average; plug in your own.

Cost per mile: $7,350 ÷ 12,000 = about 61 cents per mile.

Variable cost only (fuel + maintenance and tires + tolls share): roughly $2,300 ÷ 12,000 = about 19 cents per mile. That is the number to use when deciding whether to drive to a city three hours away.

Now see what mileage does. Drive the same car only 6,000 miles a year: fuel and wear roughly halve, but depreciation, insurance, fees and interest barely move. Total cost only drops to around $6,300, and cost per mile jumps to about $1.05.

Guesses produce a confident-looking but wrong answer. Pull the actual figures:

• Fuel: card statements or fuel receipts, plus odometer readings at each fill-up.
• Insurance: your policy declarations page.
• Maintenance: shop invoices. If you have none, start keeping them now; see how to keep car maintenance records.
• Depreciation: your purchase price from the bill of sale, and a conservative guess at future value. Be realistic rather than optimistic.
• Miles: odometer at the start and end of the period. Our mileage checker shows how your annual miles compare with typical driving.

The easiest way to keep this current is to log fuel and service as it happens. A free CarManager garage records fill-ups, services and costs against each vehicle, so the number builds itself.

The IRS publishes a standard mileage rate (opens in a new tab) every year for business driving. It is designed to approximate the full cost of operating an average vehicle, including depreciation, so it is a reasonable sanity check for your full cost per mile.

If your number is far above the IRS rate, look at depreciation (a new or expensive car), low annual mileage, or high insurance. If it is far below, you probably have an older paid-off car, or you have left something out. This is a comparison only; for tax or reimbursement questions, ask a tax professional.

The levers differ by bucket:

Fixed costs

• Keep a reliable car longer. Depreciation slows sharply after the first several years.
• Shop insurance at renewal and review deductibles; see what affects car insurance rates.
• Pay down or refinance high-interest loans; our car loan calculator shows the interest at stake.
• If a second car rarely moves, its fixed costs per mile may be very high. Run the numbers on selling it.

Variable costs

• Improve real MPG with smoother driving and correct tire pressure; see how to improve your gas mileage.
• Do not over-service. Follow the interval in your owner's manual rather than a generic quick-lube sticker; see oil change interval.
• Do not under-service either. Skipped fluid changes and worn tires create far larger bills later.
• If you are choosing a next car, compare fuel and electricity costs with the EV vs gas calculator.

• Note your odometer today and 12 months ago (or use service invoices for old readings).
• Add fuel or charging spend for the year.
• Add insurance, registration and fees.
• Add maintenance, repairs and a per-mile share of tires.
• Estimate depreciation for the year.
• Add loan interest (not principal), parking and tolls.
• Divide the total by miles driven, then repeat with variable costs only.
• Or skip the arithmetic and use the cost-per-mile calculator.