Methodology & data sources.
Where every number on this site comes from, when it gets refreshed, and what we don't model. If you want to verify a figure, this page is the canonical reference.
How the calculations work.
Every interactive calculator on this site uses a small number of explicit formulas — no black-box modeling, no opinion-shaped weighting, no proprietary "scoring." If you can read arithmetic, you can verify the math.
EV vs Gas (5–15 year total cost of ownership)
The full TCO calculation, run for both vehicles and then compared:
Cost per mile
Just the fuel cost, no other variables:
Panel capacity (NEC 220.82 Optional Method)
Three steps, applied per the National Electrical Code (NFPA 70, 2023 edition):
Note: the EVSE breaker is itself sized at 125% of the charger amperage per NEC 625.42 — so a 32A charger needs a 40A breaker, a 40A charger needs a 50A breaker, etc. Adding the breaker amps captures the full continuous load.
Public-data sources.
Every numeric input the calculators use traces to a public, government, or industry-standard source. We don't generate proprietary data and we don't license private datasets. Click through to verify any value.
| What we use | Source | Refresh | Method |
|---|---|---|---|
| State gasoline prices | AAA Daily Fuel Gauge Report — state averages | Monthly | Automated scrape (regular unleaded statewide average) |
| State residential electricity rates | EIA Electric Power Monthly, Table 5.06.B | Monthly | Automated scrape (residential YTD-current cents/kWh, converted to $/kWh) |
| EV efficiency (kWh per 100 mi) | EPA fueleconomy.gov | Annual (with new model years) | Manual — combined EPA rating per trim |
| Vehicle MSRPs | Manufacturer publications | Annual (or sooner on major price changes) | Manual — base trim MSRP, no destination/dealer fees |
| State EV incentive amounts | DOE Alternative Fuels Data Center + state program pages | Quarterly review | Manual — programs change in structure (eligibility, income gates), not just amounts |
| Federal EV credits (Section 30D, 30C) | IRS — Section 30D, IRS — Section 30C | As legislation changes | Manual — status reviewed when bills affecting these credits become law |
| Electrical load methodology | NFPA 70 / NEC, Article 220.82 Optional Method | Per NEC code cycle (3 years) | Manual — formulas hand-coded against the published article |
| DC fast-charging cost ranges | Aggregated from network-published rates (Electrify America, EVgo, ChargePoint, Tesla Supercharger) | Annually or on major network pricing changes | Manual — site uses a $0.30–$0.50/kWh range as planning default |
Current data values.
This is what the calculators are running on as of April 29, 2026. If you spot a value that looks wrong, this is where to check first.
National defaults
Used when no state is selected, and as the baseline for site-wide narrative text:
| Default | Value | Source |
|---|---|---|
| National avg residential electricity rate | $0.180/kWh | EIA EPM, early 2026 YTD |
| National avg gasoline (regular) | $4.10/gal | AAA national average, April 2026 |
| DC fast-charging public rate (default) | $0.350/kWh | Network mid-range |
| Default home charging share | 80% | Industry typical (J.D. Power EV studies) |
| Default annual mileage | 12,000 mi | FHWA average personal-vehicle |
State gas prices, electricity rates, and EV incentives
All 51 states + DC. Gas: AAA, April 29, 2026. Electricity: EIA, early 2026 YTD. Incentives: state program pages, reviewed quarterly. Incentive defaults reflect generally-available rebates only; income-qualified-only programs (CA Clean Cars 4 All, CT CHEAPR, ME Efficiency Maine, MD Excise, OR Charge Ahead, VT income-based) are listed at $0 here — see each state's incentive page for nuance.
| State | Gas ($/gal) | Elec ($/kWh) | State EV rebate |
|---|---|---|---|
| Alabama | $3.84 | $0.161 | — |
| Alaska | $4.87 | $0.256 | — |
| Arizona | $4.63 | $0.158 | — |
| Arkansas | $3.74 | $0.125 | — |
| California | $5.98 | $0.315 | — (income-qualified only) |
| Colorado | $4.19 | $0.166 | $750 |
| Connecticut | $4.28 | $0.295 | — (income-qualified only) |
| Delaware | $4.15 | $0.164 | — |
| District of Columbia | $4.33 | $0.238 | — |
| Florida | $4.15 | $0.159 | — |
| Georgia | $3.70 | $0.143 | — |
| Hawaii | $5.63 | $0.412 | — |
| Idaho | $4.40 | $0.123 | — |
| Illinois | $4.53 | $0.171 | — |
| Indiana | $4.09 | $0.161 | — |
| Iowa | $3.83 | $0.128 | — |
| Kansas | $3.70 | $0.146 | — |
| Kentucky | $4.07 | $0.139 | — |
| Louisiana | $3.77 | $0.127 | — |
| Maine | $4.21 | $0.315 | — (income-qualified only) |
| Maryland | $4.19 | $0.204 | — (program funding exhausted) |
| Massachusetts | $4.11 | $0.308 | $3,500 |
| Michigan | $4.26 | $0.197 | — |
| Minnesota | $3.93 | $0.152 | — |
| Mississippi | $3.75 | $0.145 | — |
| Missouri | $3.80 | $0.120 | — |
| Montana | $4.04 | $0.131 | — |
| Nebraska | $3.84 | $0.118 | — |
| Nevada | $5.10 | $0.142 | — |
| New Hampshire | $4.12 | $0.264 | — |
| New Jersey | $4.22 | $0.231 | $1,500 base |
| New Mexico | $3.94 | $0.149 | — |
| New York | $4.24 | $0.292 | $2,000 |
| North Carolina | $4.00 | $0.141 | — |
| North Dakota | $3.78 | $0.112 | — |
| Ohio | $4.22 | $0.176 | — |
| Oklahoma | $3.66 | $0.127 | — |
| Oregon | $5.12 | $0.146 | — (Charge Ahead suspended) |
| Pennsylvania | $4.32 | $0.202 | — |
| Rhode Island | $4.14 | $0.298 | $3,000 |
| South Carolina | $3.88 | $0.158 | — |
| South Dakota | $3.86 | $0.134 | — |
| Tennessee | $3.91 | $0.130 | — |
| Texas | $3.78 | $0.156 | — |
| Utah | $4.31 | $0.131 | — |
| Vermont | $4.19 | $0.233 | — (income-qualified only) |
| Virginia | $4.09 | $0.159 | — |
| Washington | $5.54 | $0.139 | — |
| West Virginia | $4.07 | $0.146 | — |
| Wisconsin | $3.96 | $0.184 | — |
| Wyoming | $3.98 | $0.129 | — |
EV efficiency reference (2025 model year)
The 15 EVs the calculator pre-fills, with EPA-rated combined efficiency:
| Vehicle | kWh / 100 mi | EPA range (mi) | MSRP (base) |
|---|---|---|---|
| Tesla Model 3 (RWD) | 26 | 272 | $38,990 |
| Tesla Model 3 Long Range (RWD) | 25 | 341 | $42,490 |
| Tesla Model Y | 28 | 310 | $44,990 |
| Hyundai Ioniq 6 | 24 | 361 | $38,600 |
| Hyundai Ioniq 5 | 30 | 303 | $41,800 |
| Kia EV6 | 29 | 310 | $42,600 |
| Kia EV9 | 35 | 304 | $54,900 |
| Chevy Equinox EV | 31 | 319 | $33,900 |
| Chevy Blazer EV | 31 | 334 | $45,995 |
| Ford Mustang Mach-E | 33 | 250 | $42,995 |
| Ford F-150 Lightning | 48 | 240 | $52,090 |
| Nissan Ariya | 31 | 304 | $39,590 |
| VW ID.4 | 30 | 291 | $39,735 |
| BMW iX xDrive50 | 32 | 324 | $87,100 |
| Rivian R1S | 35 | 321 | $75,900 |
Refresh cadence.
Data drift is the most common failure mode for calculator sites. Without a refresh discipline, a "$0.16/kWh national average" written in 2023 quietly becomes a 2026 lie. We have an explicit cadence per data type:
- State gas prices: automated monthly via
tasks/refresh-evgascalc-data.py, scraped from the AAA Daily Fuel Gauge state averages page. - State residential electricity rates: automated monthly via the same script, scraped from EIA Electric Power Monthly Table 5.06.B.
- State EV incentive amounts: reviewed by a human quarterly. Programs change in structure (new income gates, MSRP caps, eligibility windows), not just dollar amounts — automation alone would miss those changes.
- Federal EV / 30C credits: reviewed when bills affecting these credits become law. The Section 30D credit was sunset on September 30, 2025 by the One Big Beautiful Bill Act — reflected on this site within days. The Section 30C residential charging credit sunsets June 30, 2026.
- EV efficiency and MSRP data: reviewed annually with new model year releases.
- NEC reference (panel calculator): reviewed per code cycle (every 3 years). Currently NEC 2023 (NFPA 70).
The "Last refreshed" timestamp at the top of this page reflects the most recent verification of the data block; the date stamps in the calculator footers reflect their most recent automated refresh.
Known limitations.
Honest disclosure beats opaque sophistication. These are the cases where the calculators will produce an inaccurate result, and what to do instead:
Heat pump with electric resistance backup (panel capacity)
Per NEC 220.82(C)(3), a heat pump compressor plus electric-resistance supplemental heat should be summed (100% of compressor + 65% of supplemental). The current panel calculator treats AC and electric heat as alternatives (largest of (C)(1) or (C)(4)), which under-counts the combined heat-pump-plus-strip-heat case by up to roughly 6,500 VA (~27A at 240V). If your home has this configuration, treat the result as directional only and have a licensed electrician verify with a proper 220.82(C)(3) calculation. Code fix queued.
Solar PV / battery storage (panel capacity)
The panel calculator computes service load demand only. Homes with rooftop solar PV or battery energy storage require an additional NEC 705.12 busbar / 120% rule check — that's a separate analysis from the 220.82 service load calculation. We don't model it. If you have solar or storage, share both calculations with your electrician.
Multifamily dwellings, ADUs, multiple kitchens (panel capacity)
The panel calculator uses NEC 220.82, which is specific to single-family dwellings. Multifamily buildings, accessory dwelling units, and homes with multiple kitchens use NEC 220.84 or modified calculations. The result on this site is not appropriate for those configurations.
Pool pumps, well pumps (panel capacity)
The current UI doesn't have separate inputs for pool pumps, well pumps, or sub-panel feeders. They count as fixed appliances under 220.82(B)(4); if you have one, you can manually add its VA to a "fixed appliance" line if you know it, but the calculator doesn't yet prompt for it. Result: under-count for pool/well-pump homes (conservative direction would be to mentally add 2,000–4,000 VA).
AC nameplate VA (panel capacity)
The AC nameplate values (2-ton: 4800 VA, 3-ton: 7200 VA, 4-ton: 9600 VA, 5-ton: 12000 VA) are slightly conservative for modern SEER 14+ split-system condensers, which typically run lower. This biases the calculator toward "you need an upgrade." Direction of error is safe (won't cause fire) but may suggest an unnecessary panel upgrade.
State gas prices are statewide averages (TCO + cost per mile)
AAA reports a single statewide regular-unleaded average. Actual prices vary 10–25% by metro within a state (e.g. SF Bay vs Bakersfield, NYC vs upstate NY). For a more accurate personal calculation, override the gas price with what you actually pay at your local pump.
Public charging cost variance (TCO)
The default $0.35/kWh public-charging rate is a network mid-range. Actual cost depends heavily on which network, membership status, time-of-use pricing, and geographic market. EVgo and Electrify America peak prices range $0.43–$0.56/kWh in some markets; subscription pricing can drop to $0.30. If most of your charging is public, override this default with your actual network's rate.
Editorial standards.
Source attribution
Every numeric input, every authority claim, and every legal/regulatory reference on this site links to a public primary source. If you find a number on a calculator page or blog post that lacks attribution, that's a bug — please email us and we'll fix it.
No paid placements
This site does not currently run advertising, accept sponsored content, or include affiliate links to vehicle manufacturers, charging networks, EVSE vendors, or installation services. If that ever changes, this page will be updated to disclose the relationship before any sponsored content goes live.
AI assistance
Blog posts on this site are drafted with AI assistance (Claude, occasionally Gemini) and reviewed by a human editor before publishing. Calculator formulas and electrical-code logic are hand-coded against primary source documents (NEC 2023, IRS publications, EPA fueleconomy.gov, EIA Electric Power Monthly), not AI-generated. When AI-grounded research is used to validate or update content, the conversation log is retained internally for quality review.
Correction policy
When errors surface — whether through user reports, internal audits, or fact-checking — we correct the underlying data and code promptly, then update the affected pages. A summary of the most recent significant correction:
Recent corrections
- 2026-04-29Logic audit: refreshed all 51 state gas prices and electricity rates to current AAA/EIA values; corrected NEC 220.82(C) electric-heat demand factor from 100% to 65%; updated state EV incentives reflecting program changes (CA CVRP closed, CT/ME/OR/VT shifted to income-qualified, NJ base reduced to $1,500); corrected federal $7,500 credit references to reflect Sept 30, 2025 sunset; softened authority language site-wide; added planning-grade disclaimer to panel calculator.
- 2026-04-28Visual redesign ("Voltage" theme) — calculation logic preserved verbatim; new disclaimers added to result cards.
Limits of this calculator
None of the calculators on this site are a substitute for professional advice. The panel capacity calculator does not replace a licensed electrician's permit-grade load calculation. The TCO calculator does not replace a tax professional's review of your individual tax situation. The EV incentive listings do not replace each program's own eligibility review. Use these tools to inform a question; use a professional to answer it definitively.