EV Charging Cost Calculator

The EV Charging Cost Formula

Battery energy added equals usable capacity multiplied by the percentage-point state-of-charge increase. Wall energy equals battery energy divided by wall-to-battery efficiency. Charging cost equals wall energy multiplied by the all-in price per kilowatt-hour, plus any fixed session fee. Monthly cost multiplies the same session by the number of sessions entered.

Battery Energy, Wall Energy, and Loss

A 75 kWh usable battery charged from 20% to 80% stores 45 kWh. At 90% efficiency, the charger must supply 50 kWh, so 5 kWh is lost before storage. At $0.17/kWh, that session costs $8.50. Pricing the 45 kWh stored instead would understate the utility or public-charger bill by 10% in this example.

Home and Public Prices Need Different Inputs

Home rates can change by utility, season, and time of use. Public networks may combine an energy price with a connection, time, parking, idle, or membership charge. Enter the price and fixed fee that apply to the specific session. The calculator deliberately does not embed a changing national electricity average or pretend one network's price applies everywhere.

What the Estimate Does Not Predict

Charging time needs charger power, vehicle acceptance rate, and the battery's taper curve. Range added needs vehicle consumption in kWh per 100 miles and varies with speed, weather, terrain, cabin climate, tires, and payload. This page stays focused on energy and cost so it does not imply precision from inputs it never collected.

Source and Assumption Review — August 13, 2026

The energy and cost model was reviewed against U.S. Department of Energy Alternative Fuels Data Center and Federal Energy Management Program guidance. The user supplies current price and equipment efficiency. The editable 90% efficiency is a planning example within DOE's published EVSE comparison, not a universal charger specification.

Frequently Asked Questions

How do I calculate the cost to charge an EV?

Multiply usable battery capacity by the state-of-charge increase to find energy stored. Divide that by wall-to-battery charging efficiency to estimate energy drawn from the charger. Multiply wall energy by the all-in electricity price and add any session fee. The calculator performs those steps without rounding intermediate energy values.

Why does wall energy exceed the energy added to the battery?

Charging loses energy in the EVSE, onboard electronics, cables, battery conversion, and thermal conditioning. The U.S. Department of Energy has published examples ranging from 90% baseline EVSE efficiency to an illustration with about 16% wall-to-battery loss. Actual loss varies by vehicle, charger, temperature, and state of charge, so efficiency is editable.

What battery capacity should I enter?

Use usable battery capacity when the manufacturer publishes it. Gross capacity can include buffers that the driver cannot access, so multiplying gross capacity by the displayed state-of-charge change may overstate energy added. If only gross capacity is available, treat the result as a rough upper estimate.

What electricity price should I use for home charging?

Use the per-kWh price for the hours when the vehicle charges, including applicable energy taxes or adjustments if they are not shown separately. Time-of-use tariffs can differ sharply between off-peak and peak periods. The default $0.17/kWh is an editable example, not a national or local current-rate claim.

Can I use this for public fast charging?

Yes when the station bills by kWh: enter its all-in energy price and any connection fee. If it bills by minute, adds idle or parking charges, uses membership tiers, or changes power and price during the session, first convert those charges to an expected session amount or compare the result with the network's checkout estimate.

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