Who we are
Our day job is turning tariffs into invoices: time-of-use periods, tiered blocks, seasonal prices, fixed and daily charges, riders, fuel adjustments and the edge cases that make a real bill differ from the brochure. HomeWattCost applies that same machinery to the question households actually ask: what will this cost me, on my plan, at the hours I use power?
HomeWattCost is an independent project. It is not affiliated with any utility, regulator, electricity supplier, solar installer or car maker.
The numbers today
- Utilities modeled
- 123
- Residential rate plans
- 230
- Plans checked against official documents
- 228
- Official documents cited
- 832
- States with a modeled utility
- 50 + DC
- City pages
- 92
Computed from the published data on November 12, 2026. The documents come from 140 websites, 36 of them state regulators and other government sites; the rest are the utilities’ own tariff books and rate pages.
How a tariff gets on the site
- Transcribed from the source. Each plan is read from the utility’s own tariff and rider sheets or the state commission’s filings, never from a price-comparison site. Every per-kWh charge that applies to all customers on the plan is added in: base energy, supply or default service, transmission, fuel and purchased-power adjustments, efficiency and storm riders. Fixed daily or monthly charges are kept as they are billed.
- Checked again, independently. A second pass re-opens every cited document and re-checks each number, rider and time window. A plan that cannot be confirmed from an official document is left out rather than estimated, which is why some utilities are not on the site yet.
- Cross-checked against real bills. Each plan’s all-in price for a typical home is compared with what the utility actually billed its residential customers (U.S. Energy Information Administration, form EIA-861), and with the utility’s or regulator’s published sample bill where one exists. A plan outside the expected range is held for review.
- Dated and re-checked. Every plan shows the date it was checked and links the documents it came from. Each carries a review date set by its next known change (monthly fuel factors, supply periods, rate cases); 104 plans are due for review within the next six weeks. Data is refreshed every week, and changes are logged on the rate changes page.
Where every number comes from
- Utility tariffs: the utilities’ tariff books and rider sheets and state commission filings, cited on each utility page. The 2 plans not yet checked come from the OpenEI Utility Rate Database (CC BY 4.0) and are labeled as such.
- State prices, use per home, natural gas and gasoline: U.S. Energy Information Administration (public domain), latest month August 2026.
- How a home uses power hour by hour: NREL ResStock end-use load profiles (CC BY 4.0).
- Solar production: NREL PVWatts.
- EV efficiency and range: EPA and DOE, fueleconomy.gov.
- Which utility serves a city: federal electric retail service territories (from EIA-861) or, where that map is ambiguous, an official source naming the utility (cited on the city page), with Census Bureau population estimates; a city gets a page only when one utility clearly serves it.
The methodology explains every formula and default, and data sources lists each dataset with its license.
What the numbers leave out
Results are estimates for a typical home, before sales tax and local franchise fees. They do not include low-income discounts, medical baseline allowances or critical-peak event pricing, and they use your utility’s default supply where the state has retail choice. Your bill, and your utility’s current tariff, are always the authority.
Independence and funding
HomeWattCost is free and funded only by display advertising. It does not sell electricity, solar panels, heat pumps or chargers, earns no commission on any plan or product, and does not pass your details to installers or suppliers. The calculators run in your browser and your inputs are not stored. Ads never sit between a calculator’s inputs and its result, and no advertiser has any say over the numbers.
Corrections
A tariff that has changed, or a number that looks wrong, is the most valuable message we get. Tell us the utility, the plan and, if you can, a link to the new tariff sheet or a recent bill. We check it against the official documents, correct the plan, and the change appears on the rate changes page. Write to contact@homewattcost.com.