Data sources and calculations

Every state electricity and gasoline figure on this site is sourced from published U.S. government and AAA data, with the "Data last updated" date shown on each state page and in the state data table. The sources and exact methodology are below.

Electricity prices

Electricity figures track the U.S. Energy Information Administration's state-level average residential electricity price, published monthly in EIA's Electric Power Monthly (Table 5.6.A). The value stored per state is cents per kilowatt-hour, residential rate class, for the most recent available month.

Gasoline prices

Gasoline figures track AAA's state average regular gasoline price, which AAA updates daily from its Daily Fuel Gauge Report. The value stored per state is dollars per gallon, regular grade, as an unweighted state average across cities and regions.

How the main calculator works

Annual gasoline cost equals annual miles divided by MPG, multiplied by the state's gasoline price. Annual electricity cost equals annual miles divided by the EV's efficiency in miles per kWh, multiplied by the state's electricity rate. DC fast charging applies a 2.2× multiplier to the state's residential rate, approximating typical public fast-charging network pricing rather than home rates.

If you enter an EV price premium, break-even is the number of years until cumulative fuel savings offset that extra upfront cost: premium divided by (annual gas cost minus annual electricity cost). Leave the premium at zero to compare running costs only, with no purchase price assumption.

What isn't included

Maintenance, insurance, registration fees, depreciation, and incentives are not part of these calculations. Electricity and gasoline prices are state averages, not local or utility-specific rates — your actual bill may differ, sometimes by a wide margin depending on your utility and time-of-use plan.

Update schedule

I refresh this data monthly. Each state page and the state data table display a "Data last updated" date so you can judge how current the figures are before relying on them.