EV Charging Cost Calculator

How the cost of a charge is worked out

The energy that goes into the battery is battery size x (charge to - charge from) / 100. What you pay depends on where it is metered. At home the meter sits at the wall, so it also counts the energy lost in charging. The tool adds this loss (wall kWh = battery kWh / (1 - loss)) and prices it at your home rate, blended between day and night rates by the share you charge at night. At a public fast charger the meter sits at the connector, so no loss is added, but per-minute fees and session fees are, and the result is divided by the energy that reached the battery to give an all-in price per kWh that you can compare directly.

Fast-charging time uses the lower of the charger's power and your car's maximum, at full power up to 80% and at about a third of that power above it. This is a simplified version of the real charging curve, but it captures the main point: the last 20% takes much longer than the first 80%.

A worked example

Take a 75 kWh battery charged from 20% to 80%, which puts 45 kWh into the battery. With a 10% charging loss, home charging draws 50 kWh from the wall; at 1.20 per kWh that costs 60.00, an all-in price of 1.33 per kWh delivered. The same 45 kWh at a fast charger priced at 5.00 per kWh costs 225.00, and with a 150 kW car on a 150 kW charger it takes 18 minutes.

At 18 kWh per 100 km, driving costs 24.00 per 100 km at home (18 / 0.9 x 1.20). A petrol car using 6.5 litres per 100 km at 20.00 per litre costs 130.00 per 100 km, and home charging would match that petrol car only if petrol cost 3.69 per litre, which is the break-even figure the tool shows.

Monthly cost, winter and overnight fit

Monthly figures use your weekly distance x 52 / 12, so a year with holidays or changed routines will differ. A winter adjustment raises consumption for cold weather, since heating and cold batteries both use more energy. The overnight check compares what your home charger can deliver in the hours you give it (limited by battery size) against your average daily need, so you can see whether a slow home charger is enough for how you drive.

What the example prices are, and are not

Prices in the tool are examples for each market (NOK, EUR, USD, GBP, SEK and DKK), meant to give you a realistic starting point. They are not live and nothing is converted between currencies, because tariffs are set locally. Some of the destination-charging prices are placeholders. Replace every price with what you actually pay, and treat the result as only as accurate as the inputs.

The model also leaves out battery degradation, preconditioning, and the effect of temperature and speed on consumption beyond the winter adjustment. Units and currency are stored in metric internally, so switching between kilometres, miles and mpg never loses precision.