True Cost of Ownership Calculator

How the five real costs of owning a car are added up

Five lines, summed, then divided two ways. There's no clever modelling here — the value is in what gets included, because the costs people forget are the large ones. Only one of the five arrives as a monthly bill you'd notice.

The subtlety is depreciation. It's price minus resale, which captures your capital loss regardless of how you paid. That's why financing doesn't double-count: the loan balance nets out of the arithmetic entirely, and the only thing financing adds is the interest.

depreciation = price − resale value interest = interest actually paid over the ownership period (0 if paying cash; capped at the loan term) insurance = insurance/yr × years owned maintenance = maintenance/yr × years owned fuel = (miles/yr ÷ mpg) × fuel price × years owned true cost = depreciation + interest + insurance + maintenance + fuel cost per year = true cost ÷ years owned cost per mile = true cost ÷ (miles/yr × years owned)

price

What you paid for the car — excludes sales tax, title and registration — this model has no field for any of them

resale value

What the car is worth when you sell — sets depreciation single-handedly; defaults to the site's depreciation model for your price and horizon, and re-derives whenever either changes

interest

Loan interest paid during the years you own the car — computed on price − down, with no sales tax financed, so it runs below the auto loan calculator's figure

insurance/yr

Your annual premium — defaults to $1,600; AAA's 2025 study put full coverage nearer $1,694

maintenance/yr

Annual maintenance, repairs and tyres — defaults to $1,000; AAA's 2025 figure is about $1,475, and older cars run well above either

mpg

Fuel economy in miles per gallon — use your observed figure — window-sticker numbers are optimistic for most drivers

fuel price

Price per gallon — defaults to $3.50; EIA had the US regular average at $3.855 for the week ending 13 July 2026

Interest is handled more carefully than the rest, and it's worth knowing how. Rather than taking the loan's lifetime interest, the model sums the interest rows of the amortization schedule only for the months you actually own the car. Own for three years on a five-year loan and you're charged $4,653.15 — the interest you really paid — not the $5,642.16 the full term would cost. Because interest is front-loaded, that's a meaningfully different number from simply prorating.

One consequence of leaving tax out: the loan here is $30,000, while the auto loan calculator finances $32,450 for the same car by rolling in 7% sales tax. Same car, same rate, same term, two different interest figures — $5,642.16 here against $6,102.93 there. Neither is wrong; they're answering with different assumptions about the tax, and this page's is the less realistic of the two.

Worked examples

Frequently asked questions

What this cost-of-ownership model still misses

It's the most complete of the auto calculators here and it's still missing real money. Three of its cost defaults are unsourced guesses, and one whole category of cost has no field at all.

• No sales tax, title, registration or fees — The single largest omission. On a $35,000 car in a 7% state that's about $2,450 of tax alone, plus title, registration and doc fees, and registration recurs annually in most states. Everything here also flows from an untaxed price: the loan is $30,000 rather than $32,450, so the interest is understated too. A true cost of ownership that omits the tax is understating by roughly 5%.
• The cost defaults aren't sourced — Insurance at $1,600, maintenance at $1,000 and fuel at $3.50 a gallon are typed into the component as starting positions with no citation or date. AAA's 2025 study says $1,694 and about $1,475 for the first two, and EIA had gasoline at $3.855 for the week ending 13 July 2026. All three defaults are low, and they're low in the same direction, so the headline total is conservative rather than offsetting.
• Resale value is a model, not a forecast — The field follows the years slider now — it defaults to 20% depreciation in year one then 15% a year, so 5 years on a $35,000 car gives $14,500 and 15 years gives $3,000 rather than silently holding a stale figure. But that curve is a convention, not a prediction: real depreciation swings hugely by make, model, mileage and market, and a smooth 15% a year is a poor description of the long tail in particular. Override the figure if you have a real quote, and remember your override resets if you then move the price or the horizon.
• Flat costs, and a car that doesn't age — Insurance, maintenance and fuel are constant real amounts every year. Real maintenance climbs steeply once the warranty lapses, real insurance premiums fall as the car depreciates, and fuel prices do neither. The averages are reasonable for a five-year window and increasingly wrong beyond it.
• No opportunity cost, and no discounting — The Cash option charges nothing for $35,000 of committed capital, and the finance option charges nothing for the $5,000 down payment. Nothing is discounted either — a dollar of fuel in year five counts the same as a dollar of down payment today. The comparison between the two payment methods is incomplete by construction, not by rounding.
• Parking and tolls — Urban parking and tolls can rival the fuel line and have nowhere to go here.