How to calculate EV charging cost
First calculate the battery energy requested: usable battery capacity multiplied by the difference between target and starting state of charge. A 60 kWh usable battery moving from 20% to 80% receives 36 kWh. The meter must usually supply more than the battery stores because energy is consumed by conversion, battery conditioning, electronics and cables.
This calculator treats the loss entry as the share of grid energy not stored in the battery. It divides battery energy by the remaining efficiency. With a 10% loss assumption, 36 kWh into the battery requires an estimated 40 kWh from the grid. Grid energy is then multiplied by the blended electricity rate to estimate the session cost.
Use your bill instead of a national average
Electricity pricing differs by country, region, utility, plan and time of day. It may also include taxes, fixed charges or tiered rates. The tool therefore contains no hidden national price. Enter the marginal price charged for an additional kWh during the relevant period. Fixed household charges that would exist without the car normally should not be allocated to one charging session.
If you have a time-of-use plan, enter both the day and off-peak price and estimate the share of charging completed off-peak. The calculator computes a weighted rate. For a flat plan, enter the same amount in both rate fields or set the off-peak share to zero. Public charging can use per-kWh, per-minute, flat or combined fees, so this home-focused formula should not be presented as a public-station quote.
Why charger power and vehicle limit both matter
The wall unit's advertised power is not automatically the power the car receives. The circuit, charging equipment, cable, onboard charger and vehicle settings can each impose a limit. For a simple planning estimate, this tool uses the lower of the charger rating and vehicle acceptance limit. A 22 kW AC wall unit paired with a car that accepts 11 kW AC is therefore calculated at 11 kW, not 22 kW.
Estimated time is grid energy divided by effective power. Real charging is not perfectly constant. Battery temperature, state of charge, equipment sharing, voltage, thermal management and protective settings can reduce power. The U.S. Alternative Fuels Data Center notes that time depends on depletion, capacity, battery type, internal charger capacity and charging equipment. Treat the result as a scheduling estimate, not a promised completion time.
Charging loss is an input, not a universal constant
There is no single loss percentage that is correct for every vehicle and session. Charging power, temperature, battery conditioning and auxiliary systems can affect the gap between meter energy and stored battery energy. The 10% starting value is editable and is not attributed to a specific model. If your car, charger or utility app reports both delivered and stored energy, use your own repeated-session evidence.
Be careful with definitions. Some vehicle efficiency figures already reflect electricity taken from the wall, while others describe battery-to-wheel energy. To avoid double-counting loss in the monthly estimate, determine what your displayed kWh per 100 km or miles represents. If it already includes charging losses, set charging loss to zero for that comparison.
Monthly driving cost and range added
For the driving estimate, vehicle energy use is multiplied by monthly distance and divided by 100. The selected charging-loss adjustment converts that battery demand to estimated grid demand. Multiplying by the blended tariff gives monthly cost; multiplying the monthly result by 12 gives an annualized estimate. Seasonal driving, tariffs and charging locations can make actual months different.
Range added is battery energy divided by the entered energy use per 100 distance units. It is not an official range prediction. Speed, weather, elevation, payload, heating, cooling, tires and driving style change real consumption. Switching between kilometres and miles converts both distance and energy-use inputs so the same physical scenario remains comparable.
What each result includes
| Result | Calculation and limitation |
|---|---|
| Grid energy | Battery energy divided by charging efficiency. It is an estimate of variable electricity use. |
| Blended rate | Weighted average of entered off-peak and day rates; it is not fetched from a utility. |
| Session time | Grid kWh divided by the lower entered power. Tapering and interruptions are not modeled. |
| Session cost | Estimated grid energy multiplied by blended rate. |
| Cost per 100 | Entered vehicle energy use, adjusted for loss, multiplied by blended rate. |
| Monthly and annual cost | Distance-based projection. Charger hardware, installation and finance are excluded. |
Installation and electrical safety
A cost calculator cannot determine whether a circuit or electrical service is suitable. Charging equipment installations must follow local electrical, building and permitting rules. The U.S. Department of Energy advises consulting vehicle guidance and using a qualified electrical contractor; it also notes that some homes may need additional electrical capacity for Level 2 equipment. Requirements differ by country and property.
Before buying a charger, verify connector compatibility, continuous-current requirements, cable length, weather rating, safety certification, warranty, load management and the vehicle's accepted AC power. Renters, apartments and shared parking may need owner or building approval. Never use an extension arrangement that is not permitted by the vehicle and equipment manufacturers or local code.
Official references
- U.S. Alternative Fuels Data Center: Charging Electric Vehicles at Home — explains kWh-per-distance cost calculations, time-of-use pricing, equipment and installation considerations.
- U.S. Alternative Fuels Data Center: Charging Stations — describes charging levels and the factors that change charging time.
- Natural Resources Canada: Costs of EV Charging — distinguishes home charging and several public charging fee structures; page modified July 22, 2026.
- Australian Government Green Vehicle Guide: Home Charging Calculator — uses charger rate, battery size and electricity tariff to estimate home charging.
- Green Vehicle Guide calculator instructions — states that acceptance rate and battery-protection settings can affect time.
Frequently asked questions
How much does it cost to charge an EV from 20% to 80%?
Use the vehicle's usable battery capacity and your electricity rate. A 60 kWh battery adds 36 kWh between 20% and 80%; with a 10% loss assumption, the meter supplies about 40 kWh. Multiply that by your applicable price per kWh.
Should I use charger power or vehicle charging power?
Enter both. The lower value controls the simple estimate. For home AC charging, use the vehicle's accepted AC limit rather than its much higher advertised DC fast-charging peak.
Why is the estimated grid energy higher than the battery energy?
The loss assumption accounts for energy used before it is stored in the battery. Set the assumption from reliable vehicle or charging records when available.
Does the calculator compare petrol or gasoline?
No. Fuel prices, engine efficiency and vehicle classes introduce another set of inputs. Use the separate road trip fuel cost calculator for a combustion-vehicle journey and compare like-for-like distance assumptions.
This calculator is independent and currently contains no affiliate links or paid placements. It does not recommend a vehicle, charger or tariff and does not promise savings. Future commercial relationships will be clearly labeled and will not change the calculation method or editorial criteria.