How the estimate works
Start by choosing what your energy figure measures. In the default EPA label / wall energy mode, miles multiplied by kWh per mile gives electricity drawn from your home. The calculator adds no second charging-loss adjustment.
Battery energy mode is for a figure that excludes charging losses. In that mode, the calculator divides battery energy by the share of wall electricity that reaches the battery. For example, a 10% loss means dividing by 0.90. In either mode, electricity drawn from your home is multiplied by the price you enter.
EPA's testing explanation includes Level 2 charging losses in its electric-vehicle fuel-economy figures. Selecting no extra adjustment does not mean charging has no losses; it avoids counting them twice. This explanation was checked September 4, 2026.
The EPA and DOE display EV consumption as kWh per 100 miles because a consumption measure connects directly to energy use and cost. You can find that value on the electric-vehicle fuel economy label. Actual consumption can differ with speed, temperature, cabin cooling, tires, cargo, and driving style.
Choose an electricity price that matches charging
This tool does not guess an APS, SRP, or municipal utility rate. If you have a time-of-use plan, enter the $/kWh price for the window in which charging will occur. If you use an average bill rate, remember that fixed service charges may not rise when you add EV charging, while usage-based adjustors may. The result is therefore a planning estimate rather than a bill forecast.
Check the current utility guidance before setting a vehicle timer. APS publishes its own EV charging windows, and SRP's residential plan comparison shows the current time periods for available plans. Your enrolled plan—not a generic Arizona schedule—determines the relevant price and hours.
Gas comparison and solar
The optional comparison uses only the gas price and MPG you enter. It compares fuel energy cost, not total ownership cost. Vehicle price, insurance, maintenance, depreciation, charger hardware, and electrical upgrades are outside the model.
Rooftop solar electricity is not automatically free. Charging can replace an export that would otherwise earn a bill credit, and system ownership has its own cost. To explore a solar-charging scenario, enter the value per kWh that reflects the energy you would otherwise export or buy; this calculator does not assume a zero solar rate.
Frequently asked questions
Should I use advertised range and battery size?
Use kWh per 100 miles when possible. Dividing battery size by advertised range can mix usable and gross battery capacity and may not match real-world driving.
What should I enter for charging loss?
If you use an EPA label or a wall-energy measurement, choose EPA label / wall energy; no extra loss adjustment is added. Choose battery energy only when your figure excludes charging losses, then enter a measured or clearly assumed loss percentage. Losses vary with the vehicle, charger and conditions.
Does the estimate include demand charges?
No. If your rate includes demand charges, charging power and overlap with other home loads can matter in addition to total kWh. Review the current utility tariff or your bill before making a scheduling decision.