About the car ownership cost calculator
Total cost of ownership adds up what a car costs while you keep it: the fall in its value, fuel, insurance, maintenance and loan interest. The value drops by the first-year rate, then by the later rate on what is left each year. Fuel is distance divided by economy times the price, and interest comes from a monthly amortised loan, counting only the years you own the car.
The default, a 35,000 car kept five years and driven 15,000 km a year, with 30,000 borrowed at 7% over five years, costs 46,713.48 in total: 9,342.70 a year or 0.62 per km. Depreciation of about 20,384 is the largest part, leaving the car worth 14,616.18.
Fuel, insurance and maintenance are held at today's prices for every year, and the car is assumed to sell at its depreciated value. Set the depreciation rates from resale prices for the model you are considering.
Questions
What is included in the total cost of owning a car?
Depreciation, fuel, insurance, maintenance and repairs, and loan interest over the years you keep the car. AAA's 2026 Your Driving Costs study (15 September 2026) puts the average for a new vehicle at $12,863 a year, based on five years and 75,000 miles. The default here, a 35,000 car kept five years and driven 15,000 km a year, comes to 46,713.48, or 9,342.70 a year.
What is the biggest cost of owning a new car?
Depreciation. AAA's 2026 Your Driving Costs study found new vehicles lose a weighted average of $4,422 a year, its largest ownership cost. With the defaults here, a 35,000 car losing 20% in year one and 15% a year after that is worth 14,616.18 after five years, so depreciation is about 20,384, or 44% of the 46,713.48 total.
How do you calculate car depreciation?
Multiply the value by one minus the yearly rate, once for each year owned. With 20% in the first year and 15% after that, a 35,000 car is worth 35,000 × 0.8 × 0.85⁴ = 14,616.18 after five years, and the difference, about 20,384, is the depreciation. Mileage, condition and model all move real resale prices, so check the rates against listings for similar used cars.
Does loan interest count as a cost of ownership?
Yes, because it is money paid only for borrowing. A 30,000 loan at 7% APR over five years costs 594.04 a month and 5,642.16 in interest. Only interest paid while you own the car is counted; if you sell before the loan ends, the remaining balance is repaid from the sale. A cash buyer pays no interest but gives up what the money could have earned, which is not modelled.
How much does a car cost per mile to own?
Divide the total cost by the distance driven. The default car costs 46,713.48 over 75,000 km, which is 0.62 per km or 1.00 per mile. For comparison, the IRS standard mileage rate for business driving, which may be claimed in place of actual car expenses, is 76 cents a mile from 1 July 2026 (IR-2026-29).
How accurate is the car ownership cost calculator?
Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 4 worked examples whose answers come from independent sources; for example, “35,000 car, 5 years, 15,000 km a year, 30,000 loan at 7%” is checked against Python decimal: value 35,000 × 0.8 × 0.85⁴ = 14,616.18; fuel 1,050 L × 1.75 × 5; loan 30,000 at 7%/12 over 60 months → 594.04/month, interest 5,642.16 (60 × 594.04 − 30,000).
Where does the method come from?
AAA — Your Driving Costs 2026: new vehicle ownership costs hit $12,863 annually; IRS — standard mileage rates (IR-2026-29); Microsoft Excel PMT function (monthly loan payment).