What determines an EV’s cost per 100 km
The most important figure is electricity consumption in kWh per 100 km. Then there is the price per kWh, which varies considerably depending on where you charge: at home, at a public AC charging point, or at a DC fast charger. Charging losses also play a role, because not every kilowatt-hour drawn from the outlet reaches the battery.
For a realistic calculation, you therefore need three things: the actual consumption for your driving profile, the typical price per kWh from your charging sources, and an allowance for charging losses.
The basic formula: How to calculate your electricity costs
The simplest approximation is:
Cost per 100 km = (consumption in kWh/100 km) × (price in €/kWh)
The calculation becomes more accurate when you account for charging losses. In that case, you use the amount of electricity drawn from the grid:
Cost per 100 km = (consumption × (1 + charging loss)) × price
As a rule of thumb, many setups have charging losses of around 10–15%. They may be higher in winter, on very short trips, or with unfavorable preconditioning. They are often lower when charging at home with a stable electrical installation and moderate charging power.
Typical scenarios: What 100 km can cost
Because electricity prices and consumption vary considerably, it makes sense to use scenarios rather than a single figure. The table shows sample calculations for different consumption levels and charging locations. Enter your own figures to tailor the calculation.
| Metric | Home charging (AC) | Public AC charging | Fast charging (DC) |
|---|---|---|---|
| Assumed price per kWh | your household/home-charger rate | local rate/provider | rate at the high-power charger/highway |
| Calculation | consumption × price (plus charging losses if applicable) | consumption × price (plus idle/parking-time rules if applicable) | consumption × price (often higher in winter/at speed) |
| Typical range (result) | often the cheapest | mid-range, highly dependent on the rate | often the most expensive, but the fastest |
Important: In addition to the price per kWh, public charging rates may include time-based charges or idle fees. This can significantly increase the cost per 100 km if the car remains connected for a long time after charging has finished.
How to determine your actual consumption
Manufacturer figures are helpful for comparisons, but your daily driving is what matters for calculating your costs. There are two practical approaches:
- On-board computer/statistics: Average your consumption over several weeks rather than using just one trip.
- Charging app or home-charger data: Compare the kWh charged with the kilometers driven. This directly includes charging losses.
If you frequently drive on highways, make many short trips in winter, or often use a roof box or trailer, your average will be noticeably higher than when driving at moderate speeds on rural roads.
Step by step: Calculate your own cost per 100 km
- Choose a period: For example, one month or 1,000 km, so outliers have less impact.
- Record the kilometers driven: Use the trip meter or a mileage log.
- Collect the kWh charged: Use data from your home charger, charging app, or invoices, keeping different charging locations separate.
- Determine the average cost per kWh: If you use a mix of charging sources, calculate a weighted average.
- Calculate the cost per 100 km: (kWh charged / km) × 100 × €/kWh.
The advantage of this method is that it automatically includes charging losses and does not depend on whether your car reports consumption optimistically or conservatively.
What is often underestimated
Charging losses and auxiliary systems
Heating, battery temperature management, and short trips increase energy demand. A full battery → reduced regenerative braking, which can increase consumption over the first few kilometers. For the cost per 100 km, what matters is how often these situations occur in your driving profile.
Speed and weather
Consumption rises noticeably at higher highway speeds, with winter adding further demand from cabin heating and cold battery cells. To compare costs, you should therefore always use the same route or the same period.
Rate structures at public chargers
Some rates vary by AC or DC charging, operator, or subscription model. Before longer journeys, check which card or app offers the best terms at each charging point. Otherwise, identical consumption can result in very different costs per 100 km.
Comparison with combustion-engine cars: How to keep it fair
When comparing an EV’s cost per 100 km with that of a gasoline or diesel car, do not look only at the “energy source.” Maintenance and wear are often higher for combustion-engine cars, while tire wear and insurance/financing costs may differ for EVs. For a comparison based purely on driving costs, however, the appropriate calculation is:
EV: kWh/100 km × €/kWh (using a realistic charging mix)
Combustion-engine car: liters/100 km × €/liter
The comparison is most meaningful when both figures come from your own daily driving or at least from the same conditions, including the season, route, and driving style.
Conclusion: Your figure comes from consumption × rate
“What does it cost me to drive an EV for 100 km?” cannot be answered with a fixed figure, but it is very easy to calculate yourself. Once you know your real-world consumption and typical mix of electricity rates, you have a reliable metric. For most drivers, charging at home offers the greatest potential for reducing costs, while fast charging primarily saves time and adds convenience.
