How the numbers are made
Every default on this site is listed here with where it came from. The rule for the whole site: a number you didn't type is a guess, it says so, and you can overwrite it. Verdicts are never adjusted for affiliate relationships.
Fill up, true cost per gallon
true = sign − rebates − card + detour + membership + quality
| Line | How | Source / default |
|---|---|---|
| Sign | What the station posts. Prefilled from the regional weekly average until you overwrite it. | U.S. Energy Information Administration, weekly retail gasoline prices by state, metro and PADD region. Diesel isn't published at metro level; it's estimated from regular plus the current Florida spread. |
| Rebates | Loyalty ¢/gal plus cashback-app ¢/gal, subtracted from the sign. | Program values as published by each brand, typical as of October 2026. They change often. Report a change. |
| Card | Your card's % back, applied to the price after rebates. Zeroed if you pay with the GasBuddy card, which replaces your card. | Card issuers' published rates. |
| Detour | Extra round-trip miles ÷ your MPG × price, plus (extra miles ÷ speed) × what your time is worth, spread across the gallons in one fill. | Defaults: 0 $/hr for time, 30 mph. |
| Membership | Annual warehouse fee ÷ gallons you buy a year. | Costco $65, Sam's Club $50 (basic tiers). |
| Quality | A per-gallon penalty you set for stations that aren't Top Tier certified. Default 5¢. It's the softest number on the site, and it's the one that flips winners, the receipt shows exactly where. | AAA's independent lab testing found non-Top-Tier gasoline caused 19× more engine deposits after 4,000 simulated miles. A $400 injector cleaning every 60,000 miles ≈ 17¢/gal; every 150,000 miles ≈ 7¢/gal. Top Tier brand list: toptiergas.com. |
| MPG | EPA combined for your trim, with a permanent −12% real-world adjustment applied. | EPA fueleconomy.gov. Real-world figures typically run 10–15% below the label. |
| Gallons per fill | By EPA vehicle class. | Compact 11, midsize 13, large 15, small SUV 14, standard SUV/minivan 18, pickup/van 22. |
Which way prices usually go next
The homepage sometimes says prices usually rise or fall from here. It is a pattern, not a forecast, and it never names a future price.
gap = this week's pump price in your area − the wholesale price
| Line | How | Source |
|---|---|---|
| Pump | Your area's weekly average, the same number shown above it. | EIA weekly retail survey, taken on a Monday. |
| Wholesale | The average of the five daily prices before that survey, so one odd day cannot move it. | EIA daily spot price, Gulf Coast. |
| Rising or falling | Those five days against the five before them. | Same series. |
| When it speaks | Only when the gap is in the widest or narrowest quarter your area has seen, AND wholesale is moving the other way. The middle half of the time it says nothing at all. | Each area's own quarters, fitted on up to 400 weeks. |
| What it claims | A direction and how often that has held in your area, with the count beside it. Never a price, never a date. | Refitted by hand from the full record; the file carries the date it was last fitted. |
Every area is fitted separately, because the gap is not the same size everywhere: California's runs about four times Texas's, mostly taxes and the cost of getting fuel there.
Across the 27 areas the call has held between 68% and 91% of the time, against about half for a week picked at random. It will still be wrong sometimes, and a refinery fire or a hurricane will beat any pattern, which is why it stays quiet unless the record is clear.
Station prices on the card
A price stays on the card only while it still matches the street; over a week old, it comes off. Your own tap beats it.
| Rule | How | Source |
|---|---|---|
| Live | Looked up for your ZIP when you ask, never stored. The card shows what came back this minute. | Google Places, plus drivers' reports on this site. |
| Still true? | A price prints only while it still agrees with what the street around it is charging. When it drifts, the row keeps its place and loses its number. | The site's own check against the other stations in the same result. |
| Placeholders | Three or more stations sharing one round price are a filler, not a sign, and get no vote. | Same check. |
| Too old | Anything over a week old is dropped, whoever posted it. | Seven days. |
| Your tap | Tap a price on the card and type the sign. Your report beats Google for that station for a week. | Drivers' reports, kept seven days, no location or account stored. |
No price on this card carries a date on purpose. A dated price asks you to judge it; a price that is printed here is one that already passed the check, and one that would not pass is not printed.
Hybrid, annual running cost
gas car = fuel + maintenance + insurance hybrid = fuel (better mpg, + electricity if plug-in) + maintenance + insurance × (1 + change)
| Line | How | Source / default |
|---|---|---|
| Fuel | miles ÷ mpg × gas price, computed separately for the gas car's mpg and the hybrid's EPA combined mpg. For a plug-in, only the gas-share of miles. | EPA fueleconomy.gov, with a permanent −12% real-world adjustment applied. |
| Electricity (plug-ins only) | Your chosen share of miles on the battery × kWh/100 mi × home electricity rate. The rest of the miles burn gas at the car's hybrid MPG. | EPA charge-depleting kWh/100 mi. Electricity rate: EIA average residential price for your state. Battery-mile share default 60%, editable. |
| Maintenance | ¢ per mile × miles. | AAA Your Driving Costs averages: gas cars ~9.5¢, hybrids ~8¢ (hybrids brake less on the pads but still carry two powertrains to service). |
| Insurance | Your current premium × a % change for the hybrid. | Default +5%. Hybrids usually price close to their gas twin (sometimes a little more for the battery, sometimes nothing). Only a real quote settles it. |
| Incentives | Not applied automatically. | The federal hybrid and clean-vehicle tax credits ended September 30, 2025. Check your state's list for what's left. |
Conventional hybrids and plug-in hybrids are both handled here. Only a full EV picked on this page redirects to Charge up; a full EV, plug-in, or conventional hybrid picked on Charge up redirects here as appropriate.
Charge up, annual running cost
gas car = fuel + maintenance + insurance EV = electricity + maintenance + insurance × (1 + change) + state fee + charger rental
Charge up is for fully electric vehicles only. Plug-in hybrids and conventional hybrids are on the Hybrid page above.
| Line | How | Source / default |
|---|---|---|
| Electricity | miles × kWh/100 mi × (home share × home rate + public share × public rate). | Home rate: EIA average residential price for your state, monthly. Public: network presets, Supercharger ~45¢, Electrify America ~48¢, EVgo ~55¢, Level 2 public ~30¢, typical mid-2026, editable. |
| Maintenance | ¢ per mile × miles. | AAA Your Driving Costs, September 2025 report: gas cars 11.04¢, EVs 10.07¢. The gap is smaller than the old "no oil changes" narrative suggests, EV tire wear largely offsets it. |
| Insurance | Your current premium × a % change for the EV. | Default +20%. EV premiums commonly run 15–25% higher; only a real quote settles it. |
| Charger | Buy: one-time, shown as payback, not in the annual number. Rent: monthly fee × 12, in the annual number. None: nothing. | Buy default $1,700 (Qmerit 2026 national average, typical range $749–$2,500). Rent default $32/mo (a mid-range utility charger rental plan runs $27–36). |
| Solar | Depends on how your utility credits exports. Full retail net metering: charging costs the retail credit you gave up, no change. Net billing: daytime charging costs the export rate; night costs retail. No credit: daytime charging is free. | Default credit type by state: net billing for CA, AZ, HI, UT, ID, NV; full retail elsewhere. Export credit default 7¢. Daytime charging share default 20%. |
| Battery | Shifts up to 90% of its capacity per night from daytime solar into the night charge. Only worth money when exports are credited below retail. Its payback is shown on EV charging alone, honestly. | Default 13.5 kWh, $12,000 installed. Under full-retail net metering its value is outages, and the page says so. |
| Vehicle-to-home | Flags EVs sold with V2H hardware or a documented path to it, and states pack size as home-battery equivalents. | Pack size estimated as range × kWh/100 mi (EPA doesn't publish it). V2H list is conservative; verify the trim. |
| Incentives | Listed for your state, not applied automatically. Enter what you qualify for. | U.S. DOE Alternative Fuels Data Center. The federal clean-vehicle credit ended September 30, 2025; the federal home-charger credit ended June 30, 2026. |
What's deliberately not modeled
- Purchase price, depreciation, financing, resale, Charge up is running cost, not total cost of ownership.
- The minute you arrive: a posted price can change between the check and the pump.
- Grade "midgrade", too few buyers to earn a dropdown row.
Data feeds
- Gas and electricity: EIA Open Data API. Served through this site's own functions with cached responses; direct calls only as a fallback.
- Vehicles: EPA fueleconomy.gov web services.
- Station prices: Google Places API (New),
fuelOptions. Powered by Google. Looked up live per ZIP through this site's own function, never stored; capped at the free monthly allowance. Drivers' reports: this site's own, kept seven days. - Incentives: NREL / AFDC Laws & Incentives API.
- ZIP to state: a static prefix table, no lookup.
Common questions
Where does PumpWatt's data come from?
Gas and electricity prices come from the U.S. Energy Information Administration's Open Data API, vehicle MPG and specs from the EPA's fueleconomy.gov, station prices from the Google Places API, and incentives from the NREL/AFDC Laws and Incentives API. All served through PumpWatt's own functions with cached responses.
Does PumpWatt adjust EPA MPG for real-world driving?
Yes. A permanent −12% real-world adjustment is applied to EPA combined MPG on every calculator, since real-world figures typically run 10–15% below the label.
Are verdicts adjusted for affiliate relationships?
No. Verdicts are never adjusted for affiliate relationships. A number you didn't type is a guess, it says so on the page, and you can overwrite it.
What does PumpWatt deliberately not model?
Purchase price, depreciation, financing and resale: Charge up and Hybrid are running-cost calculators, not total-cost-of-ownership ones. Also the minute you arrive (a posted price can change between the check and the pump) and the midgrade fuel grade.
How fresh are the station prices on the card?
Looked up live for every ZIP and never stored. A price is printed only while it still agrees with what the street around it is charging. Over a week old it is dropped. Three or more stations sharing one round price are treated as placeholders. Your own report from the last week beats Google for that station. No price carries a date, because a price that is printed is one that still checks out. The rules.
How current are the defaults?
Program values like loyalty and cashback rebates are current as of October 2026 and change often; use the report-a-change link if one looks wrong. Gas, electricity and vehicle data refresh from their government sources automatically.