Calculator Inputs
Example Data Table
This example shows a realistic fast-charging scenario for a mid-size EV.
| Input | Example Value | Why It Matters |
|---|---|---|
| Battery Capacity | 75 kWh | Sets the total battery size used for charge added. |
| Start Charge | 20% | Defines the beginning state of charge. |
| End Charge | 85% | Defines the target state of charge. |
| Charger Power | 50 kW | Estimates charging session length. |
| Charging Efficiency | 92% | Adds realistic energy losses. |
| Energy Price | $0.42/kWh | Calculates billed energy cost. |
| Session Fee | $1.50 | Captures flat network charges. |
| Parking Fee | $2.00/hour | Adds site parking costs. |
| Idle Fee | $6.00/hour for 10 minutes | Penalizes staying plugged in too long. |
| Vehicle Use | 18 kWh/100 km | Converts added energy into estimated range. |
Formula Used
Added Energy (kWh) = Battery Capacity × (End Charge − Start Charge) ÷ 100
Grid Energy (kWh) = Added Energy ÷ Charging Efficiency
Charging Time (hours) = Added Energy ÷ Charger Power
Energy Cost = Grid Energy × Price per kWh
Parking Cost = Charging Time × Parking Fee per Hour
Idle Cost = Idle Time in Hours × Idle Fee per Hour
Total Cost = Energy Cost + Session Fee + Reservation Fee + Parking Cost + Idle Cost + Tax
Cost per 100 km = Cost per Battery kWh × Vehicle Use per 100 km
The calculator assumes charger power is the average power delivered during the session. Real charging curves may taper near higher charge levels.
How to Use This Calculator
- Enter your EV battery capacity in kWh.
- Set the starting and target charge percentages.
- Enter the charger power and charging efficiency.
- Add the station energy price per kWh.
- Include any flat session or reservation fees.
- Enter parking fees and any expected idle time charges.
- Set the tax rate and expected monthly charging sessions.
- Enter your vehicle energy use to estimate cost per 100 km and range added.
- Press the calculate button to show the result above the form.
- Use the CSV or PDF buttons to save the result summary.
Frequently Asked Questions
1) What does this calculator estimate?
It estimates the full cost of one public charging session and projects monthly and annual spending. It includes energy price, flat fees, parking, idle time, tax, and cost per distance.
2) Why is charging efficiency important?
Not all electricity drawn from the grid reaches the battery. Heat, conversion, and charging losses increase billed energy. Lower efficiency means you pay for more electricity than the battery actually stores.
3) Does the charger power always stay constant?
No. Many EVs charge fastest at lower states of charge and slow down near higher levels. This calculator uses average power, so it gives a practical estimate instead of an exact real-time charging curve.
4) Should I use battery kWh or grid kWh?
Use battery kWh to understand usable energy added to the car. Use grid kWh to estimate what the charging network may bill you for after charging losses are considered.
5) What is cost per 100 km used for?
It helps compare public charging with home charging, gasoline, or different EVs. It converts your session cost into a travel cost using the vehicle’s energy consumption rate.
6) Why include parking and idle fees?
Many public charging locations add fees beyond electricity. Parking and idle charges can noticeably increase the final bill, especially at busy urban chargers or time-limited parking areas.
7) Can this calculator compare different stations?
Yes. Enter one station’s rates, note the result, then change energy price, fees, or power for another station. The cost breakdown and exported summary make comparisons easier.
8) Is this result exact for every EV?
No. It is a strong planning estimate. Actual costs depend on charger billing rules, tapering, weather, battery temperature, site taxes, and whether the network bills by time, energy, or both.