EV Charging Cost Calculator
Enter your EV's battery size, the state-of-charge window you want to fill, and your electricity rates, and this calculator shows what a charging session costs at home versus on public chargers, how many miles it adds, and the cost per mile. It accounts for charging losses, so the wall energy — and the bill — is a bit higher than the energy that reaches the battery.
Charge session
Rates
Home charge cost
$6.80
+36.00 kWh to battery · 40.00 kWh from wall · +126.00 mi
Public charge cost
$18.00
Home cost / mile
$0.05
Home vs public detail
Public charging costs $11.20 more than home for this session.
Cost per charge: home vs public
How it works
The energy added to the battery is its capacity multiplied by the percentage you fill: battery kWh × (target% − current%) / 100. Charging from 20% to 80% on a 60 kWh battery adds 36 kWh. But not all the electricity you draw from the wall ends up in the battery — AC home charging loses roughly 10–15% to heat and conversion, so the energy pulled from the meter is the battery energy divided by the charging efficiency (default 0.9). That wall energy is what your utility actually bills.
Cost is wall energy multiplied by your rate. The calculator computes it twice — once at your home rate and once at a public or DC-fast rate — because public charging often costs two to three times more per kWh. Cost per mile divides the charge cost by the miles added, where miles added is the battery energy times your car's efficiency in miles per kWh (a typical EV does 3–4 mi/kWh). Note that cost per mile uses the energy that reaches the battery, since that is what actually moves the car; the loss shows up as higher total cost, not fewer miles.
Home charging is almost always the cheapest option, and this tool quantifies the gap: the public premium is simply the public session cost minus the home session cost. Real-world costs vary with your exact utility tariff (time-of-use rates can make overnight home charging even cheaper), the specific charging network's pricing and idle fees, battery temperature, and charging speed. Use the calculator to compare scenarios rather than to predict a single session to the cent.
Frequently asked questions
Why is the energy from the wall more than the energy added to the battery?+
Charging is not perfectly efficient. Converting AC grid power to DC stored in the battery loses energy to heat in the onboard charger, the cables, and the battery itself, and some power runs the car's thermal management during charging. Level 2 home charging typically lands around 85–90% efficient, so to put 36 kWh into the battery you might draw about 40 kWh from the wall. Your electricity meter bills the wall figure, which is why this calculator applies the efficiency factor — ignoring it would understate your real charging cost by 10–15%.
How much cheaper is charging at home versus public fast charging?+
Usually a lot. The US average residential electricity rate is around 18.8 cents per kWh (EIA, 2026), while public DC fast charging commonly runs 40–60 cents per kWh or more, plus possible session and idle fees. For a typical 36 kWh top-up, home charging might cost around $6–7 while the same energy on a fast charger could be $16–22. Fast charging buys speed and convenience on road trips; home charging is where EVs save money day to day. This calculator shows both side by side so the trade-off is explicit.
What miles-per-kWh should I use for my car?+
Most EVs deliver between 2.5 and 4.5 miles per kWh depending on the vehicle, driving style, speed, terrain, and weather — efficiency drops noticeably in cold weather and at highway speeds. Efficient compact EVs approach 4 mi/kWh; large trucks and SUVs may be closer to 2. Your car's trip computer usually reports a lifetime or recent average; using your own figure makes the cost-per-mile result far more accurate than a generic default. The EPA's combined efficiency rating (often shown as kWh/100 miles) can be converted: miles per kWh = 100 / (kWh per 100 miles).