Cost per Mile Calculator (true cost per km of owning a car)

Understanding the car cost per mile calculator — concept and principle

This calculator works out what your car really costs per kilometre and per mile once depreciation, fuel, insurance, maintenance, tax, loan interest and parking are all counted. It helps when comparing cars, setting a mileage allowance, deciding whether to keep a second car or comparing driving with transit or car-sharing.

All costs over the miles: with the default inputs the result is $0.53 per km (= $0.86 per mile).

How it is calculated

Distance per year in km (miles × 1.609344 if you enter miles).
Depreciation per year = (purchase price − resale value) ÷ years kept.
Total per year = depreciation + fuel + insurance + maintenance + tax + loan interest + parking.
Cost per km = total ÷ km per year; cost per mile = cost per km × 1.609344.
Monthly cost = total ÷ 12.
Running costs only per km = (fuel + maintenance) ÷ km.

The principle

Car costs come in two kinds. Ownership costs, such as depreciation, insurance, tax and interest, are paid whether you drive or not. Running costs, such as fuel and wear, grow with every kilometre. Dividing the total by the distance spreads the ownership costs over the kilometres, so the more you drive, the lower your cost per km. Depreciation is usually the largest single cost of a newer car, which is why the calculator spreads the expected loss in value evenly over the years you keep it. The categories follow AAA's "Your Driving Costs" method.

Worked example

Default inputs: 15,000 km a year, price $30,000, resale $15,000 after 5 years, fuel $1,600, insurance $1,300, maintenance $800, tax $300, interest $600, parking $400.

Depreciation = (30,000 − 15,000) ÷ 5 = $3,000.00 a year.
Total = 3,000 + 1,600 + 1,300 + 800 + 300 + 600 + 400 = $8,000.00 a year.
Cost per km = 8,000 ÷ 15,000 = $0.53.
Cost per mile = 0.533 × 1.609344 = $0.86; per month = 8,000 ÷ 12 = $666.67.
Running costs only = (1,600 + 800) ÷ 15,000 = $0.16 per km.

Each point is the calculator re-run with only “Distance you drive per year” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

Distance you drive per year	Cost per km
3,750	$2.13
7,500	$1.07
11,250	$0.71
15,000	$0.53
18,750	$0.43
22,500	$0.36
30,000	$0.27

How to read the result

The full cost per km tells you what the car costs you overall. The running-cost figure is closer to the extra cost of one more trip, since you pay the rest anyway. Compare the full figure with taxi, car-sharing or public transport if you are thinking of giving up a car; compare the running figure when deciding whether to drive a particular journey. A low annual distance pushes the per-km cost up sharply.

Common mistakes

Leaving out depreciation, the largest cost for most newer cars.
Using the full loan payment instead of only the interest part.
Comparing the full cost per km with a single trip's fuel cost.
Using an optimistic resale value.

Keep in mind: Results depend on your estimates of resale value and future costs. This is a budgeting tool, not financial advice.

Frequently asked questions

What is a typical cost per mile to own a car?

AAA's 2025 study put the average new vehicle at about $11,577 a year at 15,000 miles; your own figures will differ.

Why does driving more lower the cost per mile?

Fixed costs like insurance and depreciation are spread over more miles, so each mile carries less of them.

Should I include loan repayments?

Only the interest. The principal is part of the purchase price, which is already counted through depreciation.

Sources: AAA, "Your Driving Costs" (2025 edition) · NIST Special Publication 811 (2008), Appendix B (1 mile = 1.609344 km)

Checked 9 Nov 2026. AAA, “Your Driving Costs” 2025 edition (cost categories: depreciation, fuel, insurance, maintenance/repair/tires, license/registration/taxes, finance charges; 15,000 miles a year over five years; new-vehicle average $11,577 a year); 1 mile = 1.609344 km (NIST SP 811).

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