EV Charging Cost Calculator Formula
Understand the math behind the ev charging cost calculator. Each variable explained with a worked example.
Formulas Used
Charging Cost
charge_cost = kwh_to_add * electricity_rateEnergy Added
kwh_added = kwh_to_addEst. Cost per Mile (at 3.5 mi/kWh)
cost_per_mile = electricity_rate / 3.5Variables
| Variable | Description | Default |
|---|---|---|
battery_kwh | Battery Capacity(kWh) | 75 |
current_charge_pct | Current Charge Level(%) | 20 |
target_charge_pct | Target Charge Level(%) | 80 |
electricity_rate | Electricity Rate(USD/kWh) | 0.13 |
kwh_to_add | Derived value= battery_kwh * (target_charge_pct - current_charge_pct) / 100 | calculated |
How It Works
EV Charging Costs
Electric vehicles are typically much cheaper to fuel than gasoline cars, especially when charging at home with off-peak rates.
Formula
Energy to Add (kWh) = Battery Size x (Target % - Current %) / 100
Cost = Energy to Add x Electricity Rate
Home charging at $0.13/kWh costs roughly $0.037 per mile (at 3.5 miles/kWh), compared to $0.125/mile for a 28 MPG gas car at $3.50/gallon.
Worked Example
Charging a 75 kWh battery from 20% to 80% at $0.13/kWh.
- 01Energy to add = 75 x (80 - 20) / 100 = 45 kWh
- 02Cost = 45 x $0.13 = $5.85
- 03Cost per mile = $0.13 / 3.5 = $0.037/mile
Frequently Asked Questions
How much does it cost to fully charge an EV?
A 75 kWh battery at $0.13/kWh costs about $9.75 for a full charge, providing 250-300 miles of range. This is 3-4x cheaper than gasoline for the same distance.
Home vs public charging cost?
Home charging: $0.10-0.15/kWh. Public Level 2: $0.20-0.35/kWh. DC fast charging: $0.30-0.60/kWh. Home charging is by far the cheapest option.
Why charge to 80% instead of 100%?
Charging above 80% is much slower and generates more heat, which degrades battery life. Daily charging to 80% maximizes battery longevity and is recommended by most manufacturers.
Ready to run the numbers?
Open EV Charging Cost Calculator