Methodology and sources

Everything here is computed in your browser from published data. The worked examples below are generated from the same code and test cases that check the calculators.

Data and freshness

• Gas prices: U.S. Energy Information Administration (EIA) weekly retail regular gasoline, week of Oct 12. EIA publishes state prices for nine states (CA, CO, FL, MA, MN, NY, OH, TX, WA). Other states use their EIA region's average, and the calculators label which one you're seeing.
• Electricity prices: EIA average residential price by state, Jul 2026 (EIA publishes about two months behind).
• Vehicle efficiency: fueleconomy.gov (EPA) combined ratings, model years 2016 and newer. EV ratings are kWh per 100 miles measured at the wall, so home charging losses are included.
• Prices refresh automatically every week. If a refresh fails our checks, the previous data stays live and the dates above show how old it is.

Cost-equivalent MPG and electric gas price

EV cost per mile = kWh per 100 mi ÷ 100 × your blended electricity price × (1 + real-world adjustment).

Cost-equivalent MPG = local gas price ÷ EV cost per mile. Electric gas price = EV cost per mile × your gas car's MPG.

MPGe (shown for reference) = 3,370 ÷ kWh per 100 mi. It compares energy, not cost.

Blended charging price

Blended price = home share × home price + Level 2 share × Level 2 price + DC fast share × DC fast price. On a time-of-use plan, home price = off-peak share × off-peak rate + (1 − off-peak share) × peak rate. DC fast charging is modeled per kWh; per-minute billing isn't modeled yet.

Total cost of ownership

We simulate each month. Month 0 is the cash price (price − point-of-sale discounts, plus sales tax and fees) or your down payment. Each month after that adds loan payments, fuel (optionally rising each year), maintenance per mile, insurance, and annual registration, including your state's EV surcharge for the EV. A rebate arrives in the month you choose. In the final month we pay off any remaining loan balance and credit the resale value (price × resale %, see used cars below). Break-even is the first month after which the EV's running total stays at or below the gas car's.

The federal $7,500 clean vehicle credit ended for vehicles acquired after September 30, 2025, so incentives default to $0. Check your state and utility's current incentives.

Used cars, mileage and depreciation

What changed: new and used results now use updated, cited 2026 depreciation curves with segment and model anchors, so resale values differ from earlier versions of this site.

Value curves

Each vehicle gets a value curve (the share of its new price it keeps at each age, 0 to 20 years). We pick the most specific cited 5-year figure that applies, in this order: the exact model, then its segment and tier (mainstream or luxury), then its segment, then the powertrain average. Hybrids use the gas curve shape.

A base shape sets the profile (steep early losses, flattening later). We bend it so that it hits the chosen 5-year figure exactly: curve(t) = shape(t)(ln r5 ÷ ln shape(5)), where r5 is the share of new value kept at 5 years. For example, bending the EV shape to a 30% 5-year value gives 64% kept after 1 year and 13% after 10. The curve always starts at 100% and always falls with age.

Years 11–20 are extrapolated (a constant extra yearly loss). Beyond 20 years the value curve is flat. Site estimate. Years 1–10 are the site's v1 residual-value curve, whose year-5 points (EV 41%, gas 54%) approximate the iSeeCars 2026 5-year study averages (EV 57.2% and all vehicles 41.8% lost); the curve is re-bent to each anchor's 5-year value. Years 11–20: extrapolated at a constant 12%/yr (EV) and 10%/yr (gas) further loss. Source.

EV segment averages are unweighted per-model means taken from iSeeCars resale pages, while the all-EV average (ev:any:any) is the sales-weighted figure from the iSeeCars depreciation study. Entries labeled "Site estimate" are medians we computed from the cited pages.

The model year can be up to next year, because next-year models go on sale in the fall.

Mileage

A typical car is driven 11,200 miles a year (Same basis as annualMiles: AFDC average annual vehicle miles traveled per vehicle (cars 11,026 mi, light trucks/vans 11,360 mi; FHWA Highway Statistics 2024 Table VM-1)). We adjust value by 0.5% for every 1,000 miles above or below typical for the car's age, capped at a floor of 60% and a ceiling of 115% of the age-only value so extreme odometers can't produce absurd numbers. Site estimate: about 0.5% of value per 1,000 miles above or below typical, capped at -40% / +15%. Kelley Blue Book states it compares each car with the typical mileage for its age and adjusts value down for higher mileage and up for lower mileage, but does not publish the rate Source.

Maintenance

Maintenance per mile rises as a car ages. We multiply the base per-mile rate by a factor that depends on the odometer reading. The factor is normalized so its average over 0–150,000 miles equals the lifetime-average rate in the default assumptions below (EV 1.00, gas 1.00). That means new cars now show maintenance rising over time: below the average at first, above it later. Site estimate shaped by Argonne National Laboratory (2021) Section 3.5, which finds per-mile maintenance and repair cost rises with vehicle age and mileage (gasoline fleet cars from about $0.06-0.08 per mile in year 1 to $0.29-0.34 in year 15); normalized so the average over 0-150,000 mi equals the lifetime per-mile rate Source.

Battery

• Degradation: 2.3% of capacity per year (Geotab EV battery health analysis: average annual degradation rate of 2.3%), never below 60% health. A 4-year-old EV is at about 91%.
• Range, not cost per mile: battery wear mostly reduces range, not cost per mile, so we leave efficiency unchanged and show the expected range today instead (EPA range × battery health).
• Warranty: 8 years or 100,000 miles, whichever comes first (Kelley Blue Book: federal law requires automakers to cover EV and hybrid batteries for at least eight years or 100,000 miles). A 4-year-old EV at 48,000 mi is covered now and leaves warranty in month 48.
• Replacement cost: $5,000 to $16,000 (Recurrent: out-of-warranty EV battery replacement typically ranges from $5,000 to $16,000). We never assume a replacement; instead you can set an optional battery reserve, a one-time cost added in the month the battery leaves warranty (month 1 if it already has). It defaults to $0.

Used price estimate

Estimated price = new price × value curve at the car's age × mileage adjustment, rounded to the nearest $100. You can always type your own price.

Price when new

If you don't enter what a used car cost new, we use today's average new price ($55,000 EV, $48,000 gas; source) scaled back to the car's model year by the average new-vehicle transaction price: default new price = today's average × ATP(model year) ÷ ATP(2025), rounded to the nearest $100. Model years before 2016 use 2016; model years after 2025 use 2025. New-car prices rose 43% from 2016 to 2025, so without this step older cars would be overvalued. It is still an average across all vehicles, so the calculator asks you to enter the car's own MSRP when you know it. Kelley Blue Book (Cox Automotive): U.S. new light-vehicle average transaction price in December of each year, as published in that December's report (2020 from the industry row of the December 2021 report's table). Used to scale the average new price back to a used car's model year.

Resale at the end of your ownership period uses the same curve and the odometer at that point, as a share of what you paid. A resale percentage you type overrides it. Beyond 20 years the value curve is flat, and the mileage adjustment is capped at its floor and ceiling.

Real-world efficiency

An EV's dashboard reads battery-side energy: what left the battery. Your electric bill and EPA ratings are wall-side: what came out of the outlet, including charging losses. To compare them fairly, we convert what the display shows to what the wall supplies.

Wall kWh/100 mi = 100 ÷ (display mi/kWh × charging efficiency). Charging efficiency is 0.88 (Recurrent: a typical Level 2 home charger operates at about 83-94% efficiency grid-to-battery (midpoint 88.5%, rounded down to 0.88); the article also cites the 2014 Sears et al. field study, which measured 89.4% for Level 2).

• We use one blended factor for home and public charging. DC fast charging losses differ, so treat it as an average.
• An observed MPG replaces the EPA MPG for a gas car. The real-world adjustment sliders still apply on top, so don't use both for the same effect.

Comparing cars

The Compare cars page puts two to four vehicles side by side. Settings that describe you rather than the car (ZIP, miles per year, years of ownership, electricity and gas prices, charging mix) are shared by every car. Each car has its own price, fees, financing, running costs and resale.

Cars are ranked by total cost of ownership over your period, cheapest first. A crossover is the month when one car's running total goes below another's and stays at or below it for the rest of your period, such as when a pricier EV's lower running costs make up for its higher purchase price. If a car never overtakes another by the end, no crossover is shown. The "Real-world adjustments" (EV and gas car efficiency) you set on the EV vs. gas page apply on Compare cars too; this page has no control for them.

Default EV efficiency is 30.0 kWh/100 mi · 3.3 mi/kWh (fueleconomy.gov: combined kWh/100 mi of popular 2025-2026 electric compact SUVs).

Typical new-vehicle prices

When you pick a car from the catalog and don't type a price, we use the typical price for its kind of vehicle, as of 2026-08. We try these in order and use the first one that exists: (1) the same powertrain, body type and tier (mainstream or luxury); (2) the same powertrain and body type, any tier; (3) for luxury cars only, the luxury price for that body type across all powertrains; (4) the powertrain's overall average, such as the EV average; (5) the all-powertrain price for that body type and tier; (6) the all-powertrain average for that body type; (7) the industry average. Type your own price whenever you know it.

Default assumptions

State EV registration fees

Limitations

• Prices are state or regional averages. Your own bill and local pump prices will differ, so enter them for the best answer.
• Plug-in hybrids, per-minute fast-charging pricing, and utility-specific rate plans aren't modeled yet.
• Resale values and insurance are estimates; get quotes for your situation.
• Used-car estimates are not appraisals. Condition, trim, options and local demand all move real prices.