EV Charging Cost Calculator
The promise of cheap electric driving hides in three numbers: your battery's usable kWh, your real-world efficiency, and what your utility actually charges per kWh - and the difference between a 0.10 off-peak rate and a 0.40 public rapid is the difference between driving for pennies and paying more than a diesel. This calculator runs the honest per-mile figure from your own numbers, plus the full-charge cost that decides whether topping up at home beats the pump.
The comparison column is where it gets satisfying: add a gas price and consumption and the note converts the per-unit saving into a yearly number at 12,000 units - the figure that actually wins arguments. The note also keeps one awkward truth visible: wall-to-battery charging losses run about 10% on Level 2 and worse on rapids, so the meter number and the battery number are not the same.
How to use
- Enter your battery's usable kWh and efficiency (mi/kWh or kWh/100km).
- Enter your electricity rate - check your off-peak tariff, it changes everything.
- Optionally add gas price and consumption for the per-mile showdown.
Frequently asked questions
How do I calculate EV cost per mile?
Electricity rate ÷ efficiency: at $0.15/kWh and 4 mi/kWh, that is 3.75 cents per mile - about $450 a year at 12,000 miles. The same formula works in metric (rate × kWh/100km gives cost per km), and the calculator switches units cleanly so you can compare with what your gas car burns.
Why is my real charging bill higher than this?
Charging losses: roughly 10% of the energy you pay for never reaches the battery on Level 2 (conversion heat, battery management), and DC fast charging wastes even more on top of costing 2-3× per kWh. The calculator shows the battery-math price; mentally add a tenth for home charging, more for rapids.
What efficiency number should I use?
The EPA or WLTP figure is a lab best case; most drivers see 10-20% less in mixed driving, less again in winter when cold batteries and cabin heating bite. Check your car's trip computer lifetime average - that honest number beats any spec sheet for cost math.
Is public rapid charging still cheaper than gas?
Often, barely - and sometimes not. At $0.40/kWh and 4 mi/kWh you pay 10 cents a mile; a 30 mpg car at $3.50 gas pays 11.7. Home charging at $0.15 halves that. The calculator makes the trade visible: the EV's economics depend less on the car than on where and when you charge.