How we work

This page explains where the numbers come from, how we calculate costs, and the rules we follow so the site stays accurate.

Data

Appliance data comes from the ENERGY STAR certified product datasets published by the U.S. EPA, one for each category we cover (for example dehumidifiers and refrigerators). We only add a category after checking that its dataset has enough complete figures for honest estimates. Electricity prices come from the EIA Open Data API. Both are stored in our own database; pages never call these services while you browse. See data sources for what we hold and when it was last updated.

We keep each original record and its source identifier. If a value is missing we leave it blank. We never fill gaps with estimates.

Updates

We check both sources weekly. The ENERGY STAR list is downloaded again only when the dataset has changed. EIA publishes monthly with a delay of a couple of months, so the newest month on the site is usually not the current month. Automated checks flag stale data, failed imports, unusual changes and incomplete records.

How costs are calculated

• Yearly cost = annual kWh listed by ENERGY STAR × price per kWh.
• Monthly cost = yearly cost ÷ 12, a flat average.
• Five-year cost = yearly cost × 5 at a constant price. Real prices will change.

The annual kWh is a standardized figure from a test under typical conditions. It is not a measurement of your home. The state price is a statewide average, not your utility’s rate; you can always enter your own. All calculations run on our server, so the page and the comparison tool always agree.

We do not calculate watts or hourly cost, and we never convert an efficiency rating into power, because the source data does not support it.

Which models appear

Imported models are not published automatically. A model page is indexed by search engines only when it is published, is the newest listing for its brand and model number, and has a supported cost calculation. Older duplicate listings are marked and point to the newest one.

Typical running cost by state

The “cost to run” pages multiply the median annual energy use of the current ENERGY STAR listings of a product type by a state’s average residential price. “Typical” therefore describes the list, not a particular model or home, and every page shows the figures it used. The “How it compares” block on a model page ranks the model against all comparable listings, with the same type and similar size, including those not published on this site.

Percentages published by ENERGY STAR

Where a dataset gives a percentage, such as how far a refrigerator is below the federal energy standard, we show it as published and do not recalculate it. We checked some of these against the published kWh figures and found they do not always reconcile, so we leave the standard’s own kWh figure out rather than show two numbers that disagree.

Comparisons

You can compare two or three models. We list differences and the lowest listed energy use or best efficiency where the data shows one, and we say when models are different types or sizes. We do not declare an overall winner.

Reviews

Anyone can submit a review without an account. Reviews are moderated before they appear, links are not allowed, and only approved reviews count toward the average. We do not verify purchases, so we never label a review as verified.

Editorial independence

Affiliate links never change data or calculations. Guides are written by named authors and checked against the sources they cite. If you find a mistake, tell us through the contact page, and we will correct it.