EV Charging Cost Calculator Formula
Understand the math behind the ev charging cost calculator. Each variable explained with a worked example.
Formulas Used
Cost Per Charge
charge_cost = kwh_needed * electricity_ratekWh From Wall
kwh_consumed = kwh_neededMonthly Cost (8 charges)
monthly_cost_est = kwh_needed * electricity_rate * 8Variables
| Variable | Description | Default |
|---|---|---|
battery_kwh | Battery Capacity(kWh) | 75 |
charge_pct | Charge From/To Range(%) | 80 |
electricity_rate | Electricity Rate(USD/kWh) | 0.14 |
charger_efficiency | Charger Efficiency(%) | 90 |
kwh_needed | Derived value= battery_kwh * charge_pct / 100 / (charger_efficiency / 100) | calculated |
How It Works
How EV Charging Costs Work
The cost to charge depends on battery capacity, how much charge you add, your electricity rate, and charger efficiency.
Formula
kWh From Wall = Battery kWh x Charge % / Charger Efficiency
Cost = kWh x Electricity Rate
Level 2 home chargers are typically 85-95% efficient.
Worked Example
75 kWh battery, charging 80%, $0.14/kWh, 90% efficiency.
- 01Energy needed = 75 x 80% = 60 kWh to battery
- 02From wall (90% efficiency) = 60 / 0.90 = 66.7 kWh
- 03Cost = 66.7 x $0.14 = $9.33
- 04Monthly (8 charges) = $9.33 x 8 = $74.67
Frequently Asked Questions
Is it cheaper to charge at home or public stations?
Home charging is typically 50-75% cheaper than public DC fast charging. Home rates average $0.10-$0.20/kWh vs $0.30-$0.60/kWh at public stations.
How long does home charging take?
Level 1 (standard outlet): 24-48 hours for a full charge. Level 2 (240V): 6-12 hours. DC fast charging: 30-60 minutes to 80%.
How does EV cost compare to gas?
At $0.14/kWh, an EV costs about $0.04/mile vs $0.12/mile for a 30 MPG car at $3.50/gallon. EVs are roughly 3x cheaper per mile.
Ready to run the numbers?
Open EV Charging Cost Calculator