Cost per km is what your car costs you for each kilometre of work. It helps you work out what each trip costs before you count what you earn.
What goes into the calculation
Add up what you spend to work with your car and divide by the km you drive. There are two types of cost:
- Variable: energy, meaning fuel or electricity. It increases with distance.
- Fixed: maintenance, insurance, loan payment or rent, vehicle taxes and fees, and other costs such as cleaning, phone and tolls. You pay these even when the car is parked.
Count each cost once. If rent already includes insurance, don't count it again. Energy doesn't go in “Other” either: consumption and price already account for it.
The calculation, step by step
- Energy per km: consumption divided by 100, times the price. With 6 L/100 km and €1.80 per litre: 6 ÷ 100 × 1.80 = €0.108 per km.
- Monthly fixed costs: add maintenance, insurance, loan payment or rent, and other costs. Divide a yearly cost, such as vehicle taxes, by 12 before adding it.
- Monthly km: workdays per week, times km per day, times 52, divided by 12.
- Full cost per km: energy per km plus monthly fixed costs divided by monthly km.
An example
Five days a week, 200 km a day, with 6 L/100 km and fuel at €1.80 per litre. Each month, €40 for maintenance, €60 for insurance and €30 for other costs, with a car you own and no loan payments.
Monthly km: 5 × 200 × 52 ÷ 12 ≈ 4,333.33 km.
| Cost | Type | Per month | Per km |
|---|---|---|---|
| Energy | Variable | €468.00 | €0.108000 |
| Maintenance | Fixed | €40.00 | €0.009231 |
| Insurance | Fixed | €60.00 | €0.013846 |
| Other | Fixed | €30.00 | €0.006923 |
| Total | €598.00 | €0.138000 |
Example figures. The per km column uses six decimal places.
Fixed costs add up to 40 + 60 + 30 = €130.00 per month. Weekly energy costs are €108.00 and fixed costs are €30.00; the total is €138.00. Monthly costs are €598.00.
The calculations use unrounded values, including monthly km. The calculator rounds money to six decimal places, then to two. It shows €0.14 per km: €0.11 for energy and €0.03 for fixed costs, calculated as the total minus energy. Weekly and monthly costs are also calculated before rounding.
What changes the result
The more km you drive each month, the less fixed costs weigh on each km. With fewer km, each km costs more. The result changes when you change your schedule, car or contract.
If you rent the car, enter rent instead of a loan payment. If you have a loan payment, include it in full. If you also use the car for yourself, the result is higher because fixed costs are divided only by work km.
If you work in miles, use miles per day and consumption in mpg. Energy per mile is the price per gallon divided by consumption in mpg.
How to use it
Compare an offer with what it costs you: multiply cost per km by the trip's km, including the drive to the passenger. A trip of 10 km plus 2 km to pickup at €0.14 per km costs 12 × 0.14 = €1.68.
In the earnings calculator, choose “I know the cost” and enter this number. It's an estimate based on the numbers you entered, so redo the maths from time to time with your energy price and monthly costs.
General information, not tax or legal advice.
