Guide
How to Calculate the Real Cost of Owning a Car
Purchase price is the smaller half. Here is how to price the rest of ownership.
Split the cost into three parts
Ownership costs fall into acquisition, running and depreciation. Acquisition is the purchase price or the loan payments. Running costs are fuel, insurance, servicing, tyres, registration and taxes. Depreciation is the value the vehicle loses while you own it.
Most buyers compare only the first, occasionally the second, and almost never the third — which is often the largest.
Convert everything to a monthly figure
Annual costs such as registration and insurance should be divided by twelve so they sit alongside fuel in one comparable number. Predictable service items can be spread the same way.
A monthly total is what you can honestly test against your budget. An annual total is easy to admire and easy to ignore.
Use cost per kilometre to compare options
Dividing total cost by distance travelled produces a single figure that compares a cheap car driven a lot against an expensive one driven rarely. It also makes individual journeys tangible — a 40 km round trip at 0.55 per kilometre costs about 22, before parking.
Do not forget the small recurring costs
Parking, tolls, cleaning, occasional fines and the extras added at service time are individually minor and collectively significant. Include them in maintenance rather than pretending they are one-offs.
Separate fixed and distance-based costs
Insurance, registration, parking and loan payments usually continue whether you drive a little or a lot. Fuel, tyres and some maintenance rise with mileage. Keeping these groups separate helps you answer two different questions: what does it cost to keep the vehicle, and what does each additional kilometre cost? This distinction is useful when comparing a car with public transport or deciding whether an extra trip is worth making.
Depreciation is a real expense
A car loses value as it ages and as kilometres accumulate. You may not write a cheque for depreciation, but it reduces the amount you recover when you sell the vehicle. For a purchased car, a simple estimate is the purchase price minus expected resale value divided over the period you expect to own it. The exact pattern varies by model, age and market, so treat the result as an estimate rather than a guaranteed resale figure.
Use realistic fuel consumption
Manufacturer fuel figures can differ from everyday driving because traffic, air conditioning, road conditions, tyre pressure and driving style all affect consumption. If you have several months of fuel receipts, your own average is usually more useful. Convert litres or gallons into a cost per kilometre or mile, then multiply by expected annual distance. This makes the fuel assumption transparent and easy to update when prices or driving habits change.
Maintenance should follow the vehicle
Maintenance needs depend on age, mileage and condition. A new car may have fewer repairs but higher depreciation; an older car may have lower depreciation but more maintenance risk. Scheduled servicing is only part of the picture. Tyres, batteries, brakes and unexpected repairs also belong in the ownership budget. If you are comparing two vehicles, use the same method for both so one is not given an artificially optimistic allowance.
Include financing and opportunity cost
If the car is financed, interest is part of its cost. Entering only the sticker price hides the financing expense. A deposit also has an opportunity cost because that money could have remained in savings or been used elsewhere. You do not need to predict an exact investment return to recognise this trade-off; simply keep the deposit visible and avoid comparing a financed car with a cash purchase as if they had identical cash flows.
Turn the result into a decision
Once you know the monthly and per-kilometre cost, compare it with alternatives such as public transport, ride-hailing, cycling or a different vehicle. The comparison should include the trips you actually make. A slightly more expensive car may still be reasonable if it replaces a large amount of paid transport or saves significant time. Conversely, a cheap car can become expensive when it is rarely used. The goal is not to find the cheapest vehicle in isolation but the lowest sensible cost for your needs.
Frequently asked questions
Is depreciation really that large?
Often the largest single cost of ownership, especially in the first few years. A vehicle you resell costs less in reality than a five-year total suggests, which is why this calculator excludes it rather than guessing a resale value.
Should I include loan interest?
If you are financing, use the Loan Calculator to find the monthly payment and enter that instead of the purchase price. Interest is a real ownership cost.
Why use cost per kilometre?
It compares vehicles used at different intensities on a single scale, and it makes the cost of an individual trip tangible — useful for deciding whether a journey is worth driving.
What's the most common mistake when estimating car ownership cost?
Focusing only on the purchase price or the loan payment and forgetting depreciation, insurance and maintenance — over five years these often add up to more than the price of the car itself.
How often should I redo this calculation?
Redo it whenever fuel prices shift significantly, before a big service is due, or whenever you're comparing it against a different vehicle you're considering.
Will my actual costs match the calculator exactly?
Not exactly — insurance premiums, repair costs and depreciation vary by vehicle, region and driving history. Use the result to compare vehicles or ownership periods rather than as a guaranteed figure.
Conclusion
Purchase price is the smaller half of ownership. Convert every cost to a monthly figure, use cost per kilometre to compare options, and include the small recurring costs that are easy to dismiss and expensive to ignore.