True Cost of a Car Calculator
Purchase price, insurance, fuel, IUC, maintenance and financing, all added up into a single monthly number -- including depreciation, the cost nobody sees on a bill.
How we calculated this
Annual depreciation = (purchase price − resale value) ÷ years you keep the car. Annual fuel = (km per year ÷ 100) × consumption × fuel price. If there's financing, the total interest over the term is spread evenly across the loan's years. Everything is added up with insurance, IUC and maintenance, then divided by 12.
Why depreciation is always the surprise
When we think about the cost of a car, we think of fuel and insurance first -- expenses we see every month. Depreciation is invisible in the same way: you don't get a bill for it, but it's real money you've lost, measured by the difference between what you paid and what the car is worth when you sell it. For most cars, it's the single biggest cost of all, often bigger than fuel and maintenance combined -- and it's precisely because it's invisible that it tends to be underestimated.
The IUC and inspection calendar
IUC is charged once a year, in a month that depends on the vehicle's registration, and the exact amount is shown on the payment notice available on the Portal das Finanças. The mandatory periodic inspection also has its own schedule, which depends on the vehicle's age (starting from year 4, with increasing frequency) -- it's worth budgeting for the inspection cost and any related repairs within your annual maintenance figure.
New vs. used, at three different price points
A new car loses a big chunk of its value in the first few years -- that's where depreciation hits hardest in absolute terms. A mid-range car with a few years on it has already absorbed that steeper initial drop, but can have less predictable maintenance costs as it ages. An older, cheaper car has the lowest depreciation of all (there isn't much value left for it to lose), but tends to make up for it with higher maintenance and fuel consumption. Adjust this calculator's figures for each scenario to see which one actually works out cheaper per month.
What this calculator doesn't do
It doesn't model IUC from the car's specs (it uses the amount you already pay), and it doesn't include one-off costs like tolls, regular parking, or fines. Car financing is simplified to a standard constant-instalment system -- if your contract has different terms, the numbers may not match exactly.
Frequently asked questions
Why does depreciation count as a cost if I don't pay for it directly?
Because it's money you've lost, even if it doesn't leave your account every month -- it's the difference between what you paid for the car and what it's worth when you sell or trade it in. It's typically the biggest cost of owning a car, and the easiest to forget precisely because it's not a monthly bill.
What is IUC and where do I find out how much I pay?
IUC (Imposto Único de Circulação) is Portugal's annual road tax, based on engine size, CO2 emissions, and the vehicle's registration year. The exact amount is on your latest payment notice (available on the Portal das Finanças) -- this calculator asks for that value directly rather than trying to derive it from the car's specs.
New or used, which works out cheaper?
A new car depreciates faster in the first few years (as a percentage of its price), but has lower maintenance and warranty costs. A used car has already absorbed that steeper initial drop, but can have higher maintenance costs. There's no universal answer -- adjust the maintenance figure and resale percentage for each scenario to compare.
Related tools
You know the true cost. Now it just needs setting aside, month by month.
Otterbond helps you create a Car fund with this monthly figure, or with the full price and a target date.
Try it freeEstimate based on the values you enter, not financial advice.