EV Charging Cost Calculator

What Is an EV Charging Cost Calculator?

An EV Charging Cost Calculator estimates how much electricity will cost when charging an electric vehicle. It uses the vehicle's battery capacity, the amount of charge being added, the electricity price and an estimated charging efficiency to determine how much energy must be purchased from the electricity supply.

The calculator can be useful for electric vehicle owners comparing home charging costs, estimating the price of a charging session, comparing electricity tariffs and understanding how charging losses affect the amount paid for electricity. It can also help when comparing the estimated cost of EV charging with other transport energy costs.

Why Use an EV Charging Cost Calculator?

The amount of electricity stored in an EV battery is not necessarily the same as the electricity drawn from the grid. Charging losses mean that some of the energy consumed by the charger and vehicle does not become stored battery energy. Including an efficiency estimate can therefore provide a more useful charging cost calculation.

How to Use the EV Charging Cost Calculator

Enter the relevant battery and electricity information, then calculate the estimated energy required and charging cost in four simple steps.

1. Enter the battery capacity — Enter the usable or rated battery capacity of the electric vehicle in kilowatt-hours.
2. Enter the current and target charge — Enter the vehicle's starting state of charge and the percentage you want to reach.
3. Enter the electricity price and efficiency — Enter your electricity tariff in pounds per kilowatt-hour and an estimated charging efficiency percentage.
4. Calculate the cost — Select Calculate Charging Cost to see the estimated charging cost, battery energy added, grid energy required and other results.

How to Calculate EV Charging Cost

To estimate the cost of charging an electric vehicle, first determine how much energy needs to be added to the battery. The energy added is calculated by multiplying the battery capacity by the difference between the target state of charge and the current state of charge. For example, a 60 kWh battery charged from 20% to 80% requires approximately 36 kWh of stored battery energy.

The electricity drawn from the grid can be higher than the energy added to the battery because charging involves losses. If charging efficiency is estimated at 90%, the 36 kWh battery energy requirement would require approximately 40 kWh from the electricity supply. At an electricity price of £0.30 per kWh, the estimated charging cost would therefore be £12.00.

Understanding EV Battery Capacity

EV battery capacity is commonly expressed in kilowatt-hours (kWh). It represents the amount of electrical energy the battery can store under specified conditions. A larger battery generally requires more electricity to charge from empty to full, but the actual cost of a charging session depends on how much charge is added and the electricity price.

Why EV Charging Efficiency Matters

Charging efficiency accounts for the difference between electricity taken from the grid and energy ultimately stored in the battery. Energy can be lost through the onboard charger, power electronics, battery management systems, cables and other components. As a result, calculating charging cost from battery capacity alone can underestimate the electricity actually consumed.

Understanding EV Charging Cost Results

The estimated charging cost is based on the amount of energy required from the grid and the electricity price entered into the calculator. The charge added result represents energy stored in the vehicle battery, while grid energy required represents the estimated electricity consumed after applying the charging efficiency assumption.

Actual EV charging costs can vary from the calculated estimate. Charging efficiency can change with temperature, charging power, battery state of charge and vehicle design. Electricity prices can also vary between standard tariffs, time-of-use tariffs, public charging networks and different charging locations. For home charging, the most appropriate electricity price is the actual rate charged by your electricity supplier for the relevant period.

Frequently Asked Questions