How to use this calculator
- Split battery energy added between off-peak and on-peak periods.
- Enter the corresponding utility rates.
- Add charging efficiency and any session fee.
- Enter vehicle efficiencies and gasoline price for comparison.
#1309 · Energy & Environment Tool
Home EV Charger Energy Cost Calculator
Estimate the electricity cost of charging an EV at home using separate off-peak and on-peak energy amounts. The calculator accounts for charging efficiency, utility rates, and any per-session fee. It also reports cost per mile and compares the result with a gasoline vehicle using user-entered fuel economy and gasoline price, avoiding assumptions about local tariffs or fuel prices.
Calculator
Charging costFormula
Wall kWh by period = battery kWh ÷ charging efficiency
Total cost = off-peak wall kWh × off-peak rate + on-peak wall kWh × on-peak rate + fee
Total cost = off-peak wall kWh × off-peak rate + on-peak wall kWh × on-peak rate + fee
What the result means
Total cost is the estimated utility energy charge for the session. Demand charges, fixed monthly utility fees, taxes, and tier interactions are excluded unless included in your rates or fee.
Use marginal electricity rates applicable to the charging kWh, not the blended whole-home bill average, when your tariff has tiers or time-of-use pricing.
Example calculation
Adding 35 kWh off-peak at $0.14 and 10 kWh on-peak at $0.28 with 90% efficiency costs about $8.56 and provides about 157.5 miles at 3.5 mi/kWh.
Tips for better results
- Use your tariff’s marginal time-of-use rates.
- Include charging losses instead of pricing battery energy directly.
- Schedule flexible charging in lower-cost periods.
- Review taxes and special EV plan fees separately.
Frequently asked questions
Why is wall energy higher than energy added to the EV battery?
Charging losses mean the home must purchase more electricity than the amount stored in the battery.
Should fixed utility customer charges be included?
Usually not for one session unless the charge exists only because of EV service; use the session-fee input for incremental fixed costs.
Does the home EV charger energy cost calculation result include taxes or financing?
No. Rates and gasoline prices are entirely user-entered and can be updated for the local tariff. Add taxes, financing costs, incentives, and contract-specific charges separately when they apply.
Can I enter decimal values in this home EV charger energy cost calculation?
Yes. Decimal inputs are supported, and the calculator keeps full precision until results are displayed.
What happens if I enter zero?
Zero is accepted where it represents a valid operating condition. A value that would make the formula undefined triggers an input message instead of showing an invalid result.
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Variables and units
| Variable | Meaning | Unit |
|---|---|---|
| Eb | Battery energy added | kWh |
| η | Charging efficiency | % |
| Rw | Electricity rate | USD/kWh |
| F | Incremental session fee | USD |