Data Sources & Methodology
What This Page Covers
This page documents where our core inputs come from, how we normalize those inputs, and how calculator outputs are computed for state, city, and vehicle pages.
Primary Data Sources
EIA (U.S. Energy Information Administration)
Residential electricity benchmarks used for state-level rate baselines. Data is drawn from the EIA Open Data portal and EIA electricity price FAQ. Rates are refreshed quarterly or when EIA publishes significant revisions.
NREL AFDC (U.S. Department of Energy)
Charging-station availability and network coverage context used in state and city infrastructure summaries. Source: NREL AFDC API.
AAA
National gasoline price benchmarks used in EV vs. gas comparisons. Source: gasprices.aaa.com. Gas price figures reflect national averages and are updated when AAA publishes material changes.
IRS
Federal tax and credit eligibility context for EV-related guidance language. Sources: IRS Form 8911 (home charger credit) and IRS clean vehicle tax credits. Tax guidance is reviewed when IRS publishes updates.
Calculation Framework
Vehicle energy need is estimated from efficiency expressed in miles per kWh. Monthly energy need is split by charging mix - home versus public percentages - and each portion is costed separately using the applicable rate. Home and public charging costs are then combined into a single monthly figure.
Gas comparisons use standardized MPG and fuel-price assumptions applied consistently across all vehicle profiles so comparisons remain fair across the site. Annualized outputs scale monthly results for budget-level planning context.
Normalization Rules
All rates are expressed in USD per kWh. Cost outputs are rounded for readability while preserving comparison utility across locations. Station counts are used as coverage indicators and may differ from live maps depending on update timing and availability filters. Geographic summaries use consistent state and city slug mappings to prevent routing mismatches.
Update Schedule
Electricity rate data is reviewed quarterly and updated when EIA publishes new residential rate figures. Vehicle efficiency figures are updated when manufacturers release revised EPA ratings. Gas price benchmarks are refreshed when AAA reports material changes to national averages. Tax credit guidance is reviewed annually or when IRS publishes relevant updates.
Important Limitations
Figures on this site are planning estimates. Your actual bill can differ based on utility tariff structure, time-of-use pricing periods, weather, driving behavior, battery condition, and local fees.
For financial or tax filing decisions, consult your utility provider's official tariff schedule and a qualified advisor. See also our Site Terms and Privacy Policy.
Feedback and Corrections
If you spot a mismatch or stale value, contact us with the page URL and the specific field in question. Use the Contact page to submit a correction request. We review and address reported issues on a rolling basis.