Methodology

Last updated July 29, 2026

Every number on this site is either sourced (a certified spec pulled from a public registry, cited to it) or computed (a figure we derive with a formula published here). We never blur the two, and we never invent a spec — a missing value renders as "not published," not estimated.

How we source performance specs

Efficiency ratings (IMEF/IWF for washers, CEF for dryers, kWh/yr for dishwashers, refrigerators, ranges and cooktops) and capacity figures come from two public sources, joined on the certified model number:

• DOE CCMS (Compliance Certification Management System, regulations.doe.gov/certification-data) — the federal certification database covering the full market of certified basic models, including SKU expansion for individual models covered by a basic model.
• ENERGY STAR certification data (data.energystar.gov) — supplies the ENERGY STAR and Most Efficient designations, UPC, and certification/availability dates, and carries the model number that lets us join the two.

Where a registry doesn't disclose a field, that field renders as "not published." We don't interpolate.

Electric ranges & cooktops — why there's no gas data, and no ovens or microwaves

Ranges and cooktops are the one category on this site sourced from ENERGY STAR alone — there is no DOE CCMS certification group for cooking appliances. ENERGY STAR's cooking program certifies electric and induction ranges and cooktops only. There is no federal efficiency certification program for gas ranges or gas cooktops, and none for standalone wall ovens or microwaves — so this site has zero certified data for any of those, and no pages for them. That's not an oversight; it's the honest boundary of what the federal government certifies. Every category label on this site says "electric" for exactly this reason. Because there's no cu-ft capacity spec for cooking appliances, width in inches stands in as the size spec everywhere a capacity figure would normally appear (publish floor, "spend less" alternatives, hero stat). There is also no ENERGY STAR "Most Efficient" tier for cooking appliances (verified live, 2026-07-29) — every range/cooktop record's most_efficient field is a real, checked false, not an unknown.

The capacity-truth wedge: advertised vs. DOE-adjusted volume

A refrigerator's advertised capacity (the number on the yellow tag and the retail listing) is measured differently than the DOE-adjusted volume used to compute its certified efficiency rating — and the two are documented to diverge by roughly 30–32%. We publish both numbers on every refrigerator/freezer page and never conflate them.

How we compute annual running cost

Our headline metric per product is the estimated annual dollar cost to run it, computed from the certified annual kWh figure and an electricity price:

The default electricity price is the EIA U.S.-average residential rate (currently ~$0.1883/kWh, April 2026), refreshed on the same cadence as the corpus. Every product page with a computed cost also shows the same figure at the cheapest and most expensive state electricity price on record (computed.state_low / computed.state_high), so the national number isn't presented as universal.

For dryers specifically: gas-dryer kWh figures published by the certification registries cover the motor only, never the gas heating BTUs. We never present a gas dryer's electric kWh as its total running cost — gas dryer pages show an honest explanation instead of a dollar figure, and no gas-dryer record in our corpus carries a non-null annual_cost_usd (enforced by our merge pipeline, which fails the build if one shows up).

When ENERGY STAR hasn't published a kWh figure: what we compute — and what we show instead

DOE's certification database (CCMS) publishes a full-market spine of washers and dryers, but it doesn't carry an annual-kWh field directly — only ENERGY STAR does, and thousands of certified CCMS models have no matching ENERGY STAR record. We can compute an annual-kWh estimate directly from each model's own certified DOE efficiency factor, using the government's own published test-procedure formula — never a guess, never a fabricated conversion. But we checked both categories' formulas against real published figures before trusting them, and they didn't hold up the same way — so dryers and washers are treated differently. A page's raw data — including which basis its kWh figure uses — is in /dataset.json as kwh_basis.

• Dryers (electric only) — kwh_basis: "derived_cef". We compute AND publish the estimate. Formula: (fixed test-load weight ÷ CEF) × 283 cycles/year. CEF (Combined Energy Factor) is DOE's certified pounds-dried-per-kWh figure. The test-load weight is fixed by size class, not the individual unit's own cubic feet — 8.45 lb for standard-size dryers (≥ 4.4 cu ft), 3.00 lb for compact (< 4.4 cu ft) — and 283 is DOE's own published "representative average number of clothes dryer cycles in a year." Source: 10 CFR Part 430, Subpart B, Appendix D1/D2, §4.5.1, §4.7, Table 1. Run against the 446 dryers in our own corpus that have both a DOE CEF and a real ENERGY STAR-published kWh figure, it reproduced the published number within an average error of 0.07% (max 0.35%) — close enough that we treat it as the same metric, safe to rank against published dryer figures on this site. Every dryer page built this way is labeled "Computed estimate — not ENERGY STAR-published," in both the Verified Label energy card and an FAQ answer that shows the formula. We do not do this for gas dryers: DOE's own formula defines a gas dryer's CEF using a combined electric-plus-gas-heat energy figure (gas BTUs converted to kWh-equivalent and added to the electric draw), and CCMS only publishes that combined number — never the electric-only motor draw our gas-dryer pages require. Disaggregating it would mean guessing a split we don't have data for, so we refuse: gas dryers without a published kWh figure stay unpublished.
• Washers — kwh_basis: "derived_imef". We compute the number, but we don't show it — we show the certified IMEF instead. The formula is (capacity ÷ IMEF) × 295 cycles/year, using DOE's own published "representative average number of clothes washer cycles in a year." Source: 10 CFR Part 430, Subpart B, Appendix J2, §1 (definitions), §4.4–4.6. We checked it the same way we checked the dryer formula, and it does NOT hold up as a stand-in for ENERGY STAR's own published washer kWh figures: run against the 379 washers in our corpus with both a DOE IMEF and a real ENERGY STAR figure, the DOE-formula result overshot the published figure by 2.85x to 9.4x, with no consistent ratio (mean +334%, no fixed conversion factor to back out). That's expected, not a bug — IMEF's denominator is, by its own regulatory definition, an integrated per-cycle energy figure that bundles the washer's own electricity with the energy to heat its wash water (assuming an electric water heater) and the extra energy left over to dry a load the washer didn't fully wring out, while ENERGY STAR's consumer-facing washer kWh figure is computed under a separate FTC EnergyGuide-rule formula (16 CFR Part 305) that weights water-heater fuel mix nationally and isn't derivable from IMEF and capacity alone. A number that runs 3–9x higher than the real published figure for the same washer isn't a useful estimate even with a disclosure label — on a site whose whole premise is real running cost, a reader looking at one page reads the dollar figure, not the methodology note. So as of 2026-07-29, we don't compute or show an annual kWh or dollar-cost figure at all for the 962 washers in our corpus with a DOE IMEF but no ENERGY STAR-published kWh figure. Instead, every one of those pages shows the washer's certified IMEF plainly — a real, DOE-published, cross-comparable efficiency number (higher is more efficient), just not converted into an energy or cost figure. These records still get a full page: our thin-content publish floor treats a certified IMEF + capacity as sufficient on its own, without requiring a kWh/cost figure, specifically for this case.

Today that's 773 dryers with a computed-and-published kWh/cost figure, and 962 washers with a certified IMEF shown in place of one.

The thin-content publish floor

Not every certified record gets its own standalone page. A model publishes as a full page only if it has a complete energy block (kWh/yr) and a computed cost (or is a gas dryer with the honest null-cost explanation, or a washer with a certified IMEF shown in place of a computed figure — see above), plus at least one of: a capacity/volume figure, fit specs, or ENERGY STAR badge data beyond the raw kWh number. Records that don't clear that floor stay in the filterable product database and the plain browse index — findable and comparable, just without a thin, mostly-empty page of their own. Right now that's 9,276 of 15,732 records, mostly dryers missing a published kWh/cost figure.

What we don't do

• No star ratings. We don't run a proprietary score that collapses efficiency, capacity, and price into one undisclosed number. We show the sourced numbers and let you sort by what matters to you.
• No pay-for-placement. Rankings are strictly by a stated, verifiable metric, computed identically for every unit.
• No invented specs. If a registry doesn't publish a value, we mark it "not published" rather than estimate it.

Freshness

The corpus was pulled and gate-verified from DOE CCMS and ENERGY STAR on 2026-07-18. Our automated per-page freshness-stamp pipeline (which will show the exact pull date on every page) isn't wired yet — until it is, this reads: July 18, 2026. Re-pulls will follow the same DOE CCMS / ENERGY STAR cadence documented in this repo's ARCHITECTURE.md.

Affiliate disclosure

See the full affiliate disclosure. One program is live: Amazon links carry our Associates tag and may earn us a commission at no extra cost to you. Every other retailer link is a plain, untagged search and is labelled as such. No affiliate relationship influences which appliance appears, how it's ranked, or what a repair page recommends — the rankings are computed from certification data and repair evidence before any buy link is attached.

Corrections

Found a wrong spec, a stale figure, or a mismatched model number? Email erinrose451@gmail.com with the model number and what's wrong. We fix verified errors and update the "last updated" date on the affected page.

Download the data

The full derived dataset — every certified product, its sourced specs and (once wired) our computed running cost — is published machine-readable and licensed CC-BY-4.0: download /dataset.json. No affiliate parameters, no sign-up.