How the car ownership cost calculator works
Last updated 10 November 2026
Most people compare cars by the instalment. A cheaper instalment can hide a more expensive car to own. This calculator adds every cost together and spreads it over the months you plan to keep the car.
How it works
- Loss in value = price minus the value at the end, using the yearly percentage you choose.
- Interest is the interest paid during the years you own it, from the loan schedule.
- Running costs = fuel + insurance + services + tyres + licence + tolls + parking.
- True cost = loss in value + interest + running costs, divided by the months and kilometres.
Worked example
With the starting figures:
- The car loses R 211 392 in value over the period and R 143 679 goes on interest.
- Running costs come to R 5 225 a month.
- The true cost is R 11 143 a month, or R 7.43 a kilometre.
How to read your result
The headline is the true cost of owning the car each month, over the years you chose. With the starting figures it is R 11 143 a month. The cost for every kilometre divides the same total by the distance you drive.
Two other rows are easy to mix up. The instalment (R 6 820 a month with the starting figures) is what the bank collects. The cash out of your pocket (R 12 045 a month) adds the running costs to it. The true cost is different again, because it counts loss in value instead of loan repayments.
A closer look at loss in value
Loss in value is usually the largest cost of owning a car, and the one nobody pays out in cash. It is the difference between what you paid and what the car is worth at the end of the period. The calculator takes the yearly percentage you enter and applies it each year.
The percentage is an assumption. Real used car prices depend on the model, the mileage, the condition and the market at the time you sell. Try a lower and a higher number to see how much the monthly cost moves.
Why interest and loan term matter
Interest comes from the loan schedule, counted only for the years you own the car. A longer term lowers the instalment, but you pay interest for longer, so the total cost goes up.
A balloon payment lowers the instalment too, because part of the price is left until the end. It does not remove that cost. The amount is still due when the term ends, and it has to be paid or refinanced.
Running costs people leave out
The running costs row adds up several items. It is worth checking each one against your own records:
- Fuel, from the distance, the fuel use and the price per litre.
- Insurance and services, which differ by person, car and dealer.
- Tyres, worked out from the price of a set and the distance a set lasts.
- Licence and registration, tolls and parking.
What this does not cover
The result is an estimate for comparing cars, not a quote. It does not include the cost of money tied up in the deposit, repairs outside the services budget, or fines. It also assumes your fuel price, distance and costs stay the same through the period.
Things to watch
- Loss in value is an estimate. Used car prices vary by model, mileage and condition.
- Fuel price changes month to month. Update it.
- A longer loan lowers the instalment but raises the interest.
- The balloon payment is due at the end and must be paid or refinanced.
For the finance on its own, use the car finance calculator. Read the full disclaimer.