This page explains where every number on kWhStats comes from and how it is calculated. The latest monthly data covers July 2026.
Electricity prices
Monthly average prices come from the U.S. Energy Information Administration's retail sales data (EIA Open Data API, route electricity/retail-sales), compiled from forms EIA-861M and EIA-861. The average price for a state and sector (residential, commercial, industrial) is total revenue divided by total kWh sold, as published by EIA, in cents per kWh. It reflects what customers paid for both energy and delivery, not just the energy charge, although some taxes billed separately are not included.
EIA publishes each month's data about three months later and revises recent months, so we download the full last 36 months each time we update. The year-over-year change compares the latest month with the same month a year earlier. Rankings run from 1 (cheapest) to 51 (the 50 states and DC); states with equal values share a rank.
Average bills and usage
- Average monthly bill = residential revenue ÷ residential customers, for each month.
- Average monthly usage = residential kWh sold ÷ residential customers.
- "Last 12 months" figures are the average of the 12 most recent monthly values. Headline bills use this 12-month average so that a hot summer or cold winter month does not distort them; the latest single month is shown separately.
- When EIA leaves a month's kWh sold blank but publishes revenue, we calculate it from EIA's own definition: kWh sold = revenue ÷ price. We have tested this against every month where both are published, and it matches within 0.1%.
Business bills use the same method with commercial data. They average every kind of commercial customer, from small shops to large buildings.
Utilities and suppliers
Lists of utilities, their customer counts and their average rates come from EIA's annual survey of electric utilities (EIA-861, data year 2025). A utility's average rate is its full-service residential (or commercial) revenue divided by kWh sold. We show it only for utilities with at least 100 customers in that group, because averages over a handful of accounts are not meaningful prices. Delivery-only utilities, whose customers buy electricity from a retail supplier, have no full-service rate. Retail suppliers are listed separately, by number of residential customers, and never as a recommendation.
ZIP code lookups
The bill calculator matches ZIP codes to utilities using the National Renewable Energy Laboratory's U.S. Utility Rates by ZIP Code (2024, CC-BY 4.0). For a utility you pick, we use its latest EIA-861 rate, or its NREL 2024 rate if EIA-861 has none. If no utility with a full-service rate is listed for your ZIP code, for example in areas where homes buy power from retail suppliers, we use your state's latest average price. A ZIP code that is not in the NREL file is matched to its state by its first three digits.
Appliance and EV costs
- Cost = kWh × price per kWh. For an appliance, kWh per month = watts × hours a day × 30.4 ÷ 1,000; appliances rated in kWh per year are divided by 12.
- Typical yearly use per household comes from EIA's 2020 Residential Energy Consumption Survey (tables CE5.3a and CE5.3b): the average for homes that have that appliance, converted from million Btu at 3,412 Btu per kWh.
- Typical wattages come from the U.S. Department of Energy's appliance list (as republished by Virginia Cooperative Extension). Window air conditioner wattage is cooling capacity ÷ efficiency rating (CEER) of ENERGY STAR certified models; LED bulb wattage comes from ENERGY STAR certified 60-watt-equivalent bulbs. ENERGY STAR data was downloaded 2026-10-20.
- EV efficiency is the median EPA rating (kWh per 100 miles, measured at the wall) of 321 model-year 2026 electric cars, from fueleconomy.gov.
Where each state's power comes from
Generation mix figures use EIA's annual net generation by fuel for each state (2025, all sectors). Statements such as "generates more electricity than it uses" compare in-state generation with retail sales in the same year. The short descriptions of each state are written by us and checked automatically: every factual claim in them is tested against this data each time the site is built.
How the site is updated and checked
- Monthly refresh. On the 20th of each month the site downloads the latest data from every source, recalculates every figure and rebuilds every page. The date of the last update is shown on each data page.
- Cross-check against the source. After each download, a few states picked at random are requested from EIA again, one at a time, and must match the bulk download exactly.
- Automated tests. Before anything is published, tests check that every state has a full set of plausible figures, that known values still match, that each data-backed claim in our written text still holds, and that pages are not too similar to each other. If any test fails, nothing is published and the previous version stays online.
- Link checks. Links to official sources and state shopping sites are checked on each refresh, and broken ones are fixed by hand.
Who writes and reviews the content
Figures, tables and the sentences that state them are generated from the data. The written descriptions of each state, including the sections on what drives prices there, are drafted by us and reviewed byAbdel Beldy before they are published. Statements that our data cannot check, such as a law, a market rule or a storm, are listed for review and confirmed against official sources.
Corrections
If a figure or statement looks wrong, email hello@kwhstats.com with the page and what you expected. We check every report against the source data. A wrong figure caused by our code is fixed for every page at once; a wrong written statement is corrected and noted in the change log below. If the source data itself is revised, as EIA does with recent months, the site picks up the revision at the next monthly refresh.
Limits
- Averages hide a lot of variation. Your price depends on your utility, plan, rate schedule and usage.
- Calculator results estimate energy cost from an average price. They do not include every fixed fee, tax, tier or demand charge on your bill.
- Government data is published with a delay. The data month is shown on every page.
Sources
- U.S. Energy Information Administration: retail sales data (EIA-861M/EIA-861), EIA-861 annual utility data, electric power operational data, 2020 Residential Energy Consumption Survey. Public domain.
- National Renewable Energy Laboratory: U.S. Utility Rates by ZIP Code (2024), licensed CC-BY 4.0.
- U.S. EPA ENERGY STAR certified product data (data.energystar.gov).
- U.S. EPA and DOE, fueleconomy.gov vehicle data.
- U.S. Department of Energy appliance wattage list, via Virginia Cooperative Extension publication BSE-301.
- U.S. Census Bureau ZIP Code Tabulation Areas (used only to test ZIP coverage).
Change log
- 2026-10-28: Added sections explaining what drives electricity prices in each state, reviewed before publication; added this page's update, review and corrections sections.
- 2026-10-19: Site launched.
Found something that looks wrong? Email hello@kwhstats.com.