Calculate the electricity cost of driving an electric car 100 kilometres after factoring in charging losses. Enter your car's consumption in kWh per 100 km, your electricity price per kWh and your charging efficiency, and the calculator returns cost per 100 km, cost per km, monthly cost and annual cost.
The cost per 100 km metric is the electric equivalent of L per 100 km for petrol cars. It is the cleanest way to compare running costs between vehicles, between tariffs and between home and public charging.
Formula for EV cost per 100 km
Cost per 100 km equals consumption in kWh per 100 km multiplied by electricity price per kWh, divided by charging efficiency expressed as a fraction. Cost per km is that figure divided by 100. Monthly cost is cost per km multiplied by monthly distance. Annual cost is monthly cost multiplied by 12.
Typical consumption ranges
Efficient compact EVs use 12 to 15 kWh per 100 km. Mainstream long-range sedans and crossovers sit between 16 and 20 kWh per 100 km. Larger electric SUVs and pickups at motorway speed can exceed 22 to 28 kWh per 100 km, especially in cold weather or with roof boxes fitted.
Why charging efficiency matters
Cost per 100 km calculated against battery energy understates the true bill because not every kilowatt-hour pulled from the wall reaches the battery. Dividing by charging efficiency converts battery energy into wall energy, which is what your utility bills you for. A 90 percent assumption is a sensible default for home wallbox charging.
How home and public charging change the result
The same car at the same consumption can cost very different amounts per 100 km. At 0.20 per kWh on home electricity and 90 percent efficiency, a 17 kWh per 100 km EV costs about 3.78 per 100 km. At 0.65 per kWh on a public DC charger and 92 percent efficiency, the same car costs about 12.01 per 100 km — more than three times higher.
EV vs petrol cost per 100 km
A typical petrol car at 6.5 L per 100 km and 1.70 per litre costs 11.05 per 100 km. An equivalent EV at 17 kWh per 100 km, 0.25 per kWh and 90 percent efficiency costs 4.72 per 100 km — about 57 percent less. The advantage shrinks on expensive public charging and grows on off-peak tariffs.
Frequently asked questions
How do I calculate EV cost per 100 km?
Multiply consumption in kWh per 100 km by the electricity price, then divide by charging efficiency. At 0.25 per kWh, 18 kWh per 100 km and 90 percent efficiency, the result is 5.00 per 100 km.
What is a good EV cost per 100 km?
Home charging usually delivers 3 to 7 per 100 km. Public DC fast charging can push the same car to 10 to 18 per 100 km depending on the network.
How many kWh does an EV use per 100 km?
Efficient compacts use 12 to 15. Most mid-size EVs sit at 16 to 20. Large SUVs at motorway speed can exceed 22 to 28.
Why is my real cost higher than the calculator?
Cold weather, motorway speeds, roof boxes and winter tyres raise consumption. Public charging tariffs and idle fees add more on top.
Does the calculator include road tax or insurance?
No. It calculates the energy cost of driving 100 km only. Add fixed costs separately to compare total cost of ownership.
Can I use it for kWh per mile?
Use the cost per mile calculator instead. The math is identical; only the consumption unit differs.
Should I use summer or winter consumption?
Use the figure that matches the climate you drive in most. A blended annual average gives the most realistic yearly cost.
Why divide by charging efficiency?
You pay for energy drawn from the wall, not energy stored in the battery. Dividing by efficiency converts one into the other.