EV Home vs Public Charging Cost Calculator

The economics of EV charging

Where you plug in matters more than what you drive. Public DC fast chargers routinely cost three to five times a home rate per kWh, and for a driver covering 12,000 to 15,000 miles a year the gap between charging exclusively at home and exclusively on public rapid chargers runs to $1,000 to $2,500 a year. That is the same order as the whole fuel bill on a small petrol car.

The arithmetic

Monthly kWh = miles driven ÷ efficiency (mi/kWh)

Monthly cost = kWh × rate per kWh

Cost per mile = rate ÷ efficiency

Worked example: 1,000 miles a month, 3.5 mi/kWh, $0.13/kWh at home.

• Energy: 1,000 ÷ 3.5 = 285.7 kWh
• Cost: 285.7 × $0.13 = $37.14 a month
• Per mile: $0.13 ÷ 3.5 = $0.037

A 25 MPG petrol car covering the same 1,000 miles at $3.50 a gallon burns 40 gallons and costs $140, or $0.14 a mile. Home charging is running at roughly a quarter of that. Swap the home rate for a $0.45/kWh rapid charger and the EV figure becomes $0.129 a mile, which is essentially the petrol car. That single substitution is the whole argument for a home charge point.

Battery size and charges per month

The calculator uses your battery capacity to translate the monthly total into something more concrete: what one full charge costs, and how many of them a month’s driving works out to. A 75 kWh pack at $0.13 costs $9.75 to fill from empty, and 285.7 kWh a month is 3.8 fills. On a rapid charger at $0.45 that same fill is $33.75.

The three charging levels

Level 1 (120 V household outlet) adds 3 to 5 miles of range an hour, so 30 to 50 miles across an overnight session. The cable comes with the car and there is nothing to install, but you still pay for the electricity at your standard household rate. Fine for a plug-in hybrid or a short commute, painful for anything else.

Level 2 (240 V) adds 20 to 30 miles an hour, which covers a full day’s driving overnight for almost anyone. At home it needs a dedicated circuit; publicly it usually runs $0.20 to $0.40/kWh. This is what most owners use daily.

DC fast charging adds 100 to 300 miles an hour and takes a typical pack to 80% in 20 to 40 minutes. It cannot be installed at a house, it usually costs $0.35 to $0.60/kWh, and the connector matters: CCS on most non-Tesla cars, CHAdeMO on older ones, and NACS spreading across the industry after Tesla opened the standard. Tesla’s own Superchargers run $0.25 to $0.45/kWh and are generally cheaper than the third-party networks.

Typical US rates, approximate and moving:

State rates vary more than most people expect. Hawaii sits near $0.42/kWh and California around $0.30, while Washington, Idaho and Louisiana are closer to $0.10 and the national average lands near $0.16. Charge at home in Idaho and an EV is almost free to run; do it in Hawaii and the maths gets a lot less obvious.

Time-of-use tariffs

Most utilities now offer an EV-specific rate with an off-peak window, typically 9 PM to 7 AM, at $0.06 to $0.15/kWh. Peak hours on the same tariff often cost more than the flat rate you left, so the saving depends entirely on actually charging at night. Every EV sold can schedule this, and it usually takes about two minutes to set up. Expect $200 to $800 a year for a typical driver.

Does a home charge point pay for itself?

Hardware runs $200 to $1,200, the 240 V circuit $300 to $1,500, and permits another $50 to $200, so $500 to $2,500 all in. Against public rapid charging the saving is the $1,000 to $2,500 a year above, which puts payback somewhere between six months and two and a half years. Against Level 1 the case is weaker on pure cost and stronger on convenience, though a time-of-use tariff usually tips it.

Efficiency varies more than people expect

That is a 2.7x spread from the Ioniq 6 to the Hummer, and energy cost per mile scales with it exactly. A Hummer charged at home costs about the same per mile as an Ioniq 6 charged on a public rapid charger.

A note on fast charging and battery life

Frequent DC rapid charging does shorten pack life, and the effect is real enough that Tesla has throttled peak charging speed on high-mileage cars. For occasional road-trip use the difference is small. The rule most owners settle on is Level 2 at home for daily driving, rapid charging saved for trips, and a daily ceiling of 80% rather than 100%.

One more thing the calculator cannot see: cold weather. Below freezing, range drops 20 to 40%, so a winter month costs proportionally more than the figures here suggest.