EV Charging at Home vs Public Charging: A Cost Comparison Worksheet

Home charging usually wins on convenience when you have a place to plug in, but the correct comparison is dollars per useful mile after charging losses and station fees. Public charging can be the practical choice for renters, apartment residents, road trips, or drivers who need rapid charging. The U.S. Department of Energy’s Alternative Fuels Data Center says most EV drivers charge overnight at home and gives a teaching example: at 10.7 cents/kWh, a 54-kWh battery costs about $6 to fill. Read its home-charging guidance.

Public charging prices vary by network, location, membership, time, and whether the site bills by kWh, session, or time. AFDC lists those pricing models and notes that electricity, maintenance, networking, and demand charges affect station economics. Its operations guidance is a reminder to read the station’s live price screen, idle fee, and membership terms before treating a posted price as universal.

The worksheet

Enter your vehicle’s usable battery capacity, expected miles per kWh, home all-in electricity rate, public charger price, session fee, idle fee, and charging loss assumption. Compute:

home cost per mile = (home kWh price × wall kWh per mile)

public session cost = (energy price × billed kWh) + session fee + idle fee

Use wall energy where possible; a vehicle’s battery display may omit charging losses. For home charging, include any new circuit, permit, panel, or trench work as a separate annualized equipment cost rather than hiding it in the kWh price.

Hypothetical 100-mile comparison

Assume a vehicle uses 3.3 miles per battery kWh and charging losses add 12%. Home energy needed is (100 ÷ 3.3) × 1.12 = 33.94 kWh. At an assumed all-in home rate of $0.18/kWh, home energy costs $6.11. Assume public DC charging bills 34 kWh at $0.56/kWh and adds a $1.50 session fee: $19.04 + $1.50 = $20.54. These are assumptions, not a public-network quote. A public membership discount or a different home tariff changes the result.

Then include installation. If a hypothetical $1,800 home Level 2 installation is used 6,000 miles per year for five years, allocate $1,800 ÷ 30,000 miles = $0.06/mile, or $6 per 100 miles. Home total becomes about $12.11 per 100 miles during that period. If you already have a suitable outlet and use Level 1, that installation line can be near zero, though charging is slower. AFDC notes that home Level 1 and Level 2 equipment, site conditions, electrical upgrades, labor, and permitting affect installation scope. See its installation guidance.

What can break the comparison

A utility’s time-of-use plan may make overnight charging cheaper or may raise the cost of a daytime session. Demand charges generally apply to charging-station owners rather than a household’s ordinary residential bill, but a landlord or site host may pass through costs. Public stations can add parking, idle, connection, or membership fees. Some stations are free, while others bill by time where state rules limit resale of electricity.

Ask an electrician to evaluate the service and circuit before buying equipment. Compare charging speed, connector compatibility, winter performance, and the number of vehicles sharing the circuit. Keep gross equipment and installation cost separate from operating cost, and record the date and location of every public price. That makes the worksheet useful when tariffs or network prices change.