Car Cost Per Kilometre Calculator
The real cost of running a car per kilometre, including the depreciation people leave out.
Fuel is the cost people think of and rarely the largest.
How the car cost per kilometre calculator works
Fuel is the cost people think of and rarely the largest. Depreciation usually is — a car losing 4,000 a year over 15,000 km costs 27 cents a kilometre before a drop of fuel goes in.
That is why cost per kilometre falls sharply with distance driven. The fixed costs — depreciation, insurance, registration — spread over more kilometres, so a car driven 30,000 km a year costs far less per kilometre than the same car driven 8,000, even though it costs more in total.
This is also the comparison that decides whether owning is worth it against hiring or ride-sharing for occasional use.
Formula: cost per km = (fixed costs + running costs) / annual distance
Worked examples
| Inputs | Cost per kilometre | Note |
|---|---|---|
| 15,000 km a year | £0.62 | depreciation dominates |
| A high-mileage driver | £0.32 | far less per km |
| A little-used second car | £1.56 | very expensive per km |
FAQFrequently asked questions
What does a car really cost per kilometre?
Commonly 50 to 90 cents once depreciation, insurance, registration, servicing and fuel are all counted — far more than fuel alone suggests.
Why is depreciation the biggest cost?
Because most cars lose more value in a year than they burn in fuel, particularly newer ones in their first three years.
Why does driving more reduce cost per kilometre?
The fixed costs are the same whether you drive 5,000 km or 30,000, so they spread thinner.
Should I include the purchase price?
Only the part you lose — purchase minus expected resale. The rest is still your money.
Is it cheaper not to own a car?
For low annual distances, frequently yes. Below about 8,000 km a year the fixed costs make hiring or ride-sharing competitive.
Where these figures come from
- ISO 4000 / ETRTO — tyre designation and dimensions — the width / aspect ratio / rim marking this page decodes
- UK Vehicle Certification Agency — the official UK fuel and emissions data
Last checked: September 2026. Tyre dimensions follow the ISO metric marking standard; engine formulas are the standard textbook forms.