How this calculator works
We start from miles, not from battery size, because your commute is what you actually pay for. Weekly miles are your round trip times commute days, plus other driving. Monthly miles use 52 weeks divided by 12 months.
- Battery energy = monthly miles ÷ efficiency (mi/kWh).
- Home cost = battery energy from home ÷ charger efficiency × your rate. Wall-to-battery losses are real, and your meter bills the wall side.
- Public cost = battery energy from public chargers × the per-kWh price. Networks meter at the charger, so we do not add home losses.
- Gas cost = monthly miles ÷ MPG × price per gallon.
- Overnight check = charger power × 10 hours × efficiency × mi/kWh, compared with one commute day. We call it "covers" only with a 25% buffer for cold weather and detours.
Assumptions and sources
| Input | Default | Where it comes from |
|---|---|---|
| Home electricity | $0.183 / kWh | US Energy Information Administration, Electricity Monthly Update, June 2026 residential average |
| Regular gasoline | $4.36 / gal | AAA national average for regular gasoline, October 11, 2026 |
| Level 1 power | 1.44 kW | 120V × 12A, the continuous-load limit on a standard 15A circuit |
| Level 2 power | 7.68 kW | 240V × 32A on a 40A circuit; many home installs are sized this way |
| Charging efficiency | 85% (L1) / 90% (L2) | Typical wall-to-battery range; varies by car, temperature, and charger |
| Vehicle efficiency | 2.4–4.0 mi/kWh | Rounded ranges for common US EV body styles; use your EPA label for accuracy |
What the numbers leave out
- Time-of-use rates. Many utilities offer cheaper overnight EV rates. If yours does, enter the off-peak price.
- Winter. Cabin heat and battery warming can cut efficiency noticeably in cold states. Lower the mi/kWh to see a winter month, or use the winter range estimator to see if the commute still fits.
- Installation. A Level 2 install is a one-time cost. See our Level 2 home charging cost guide for how to price it.
- Fixed fees and taxes. Your utility's monthly service charge does not change when you add an EV, so we leave it out.
How to use the result
Treat the monthly figure as a planning number, not a quote. If the gap between EV and gas is small, the decision will turn on other costs — insurance, purchase price, and resale — more than on energy. If Level 1 comes back "short," you either need a Level 2 circuit, reliable workplace charging, or a shorter commute before an EV makes daily sense.