Methodology
Last reviewed July 2026.
The ranking: cost per running watt
The homepage ranking is arithmetic on the manufacturer’s own published numbers: price ÷ continuous running watts (never the peak/starting surge — the difference), shown beside the maker’s rated noise, per-tank runtime at the published load, and inverter-vs-conventional power quality. Four rules keep it honest:
- All four numbers or no row. A unit is ranked only if its maker publishes running watts, noise (dBA), runtime and a price (MSRP or dated retail). Generac’s GP series publishes no dBA, so it is not ranked — the omission is the finding.
- Every spec traces to the maker’s page, and every price carries its source and date in the dataset. Prices drift; the linked listing is authoritative.
- Noise figures are not standardized — makers rate at different loads and distances. We show the published number and its stated conditions rather than pretending they're comparable to the decibel.
- Battery power stations are never ranked — they store power rather than generate it, so a per-running-watt figure would be arithmetic on incompatible units (why). They render in their own labeled section.
The default sort is cheapest running watt first — which surfaces big, loud conventional units above quiet inverters. That is intentional: cheapest per watt isn’t “best,” and the noise, runtime and type columns are there to show the trade you’d be making.
What we do — and emphatically don't
We test nothing, and we give no safety advice. Portable-generator carbon monoxide kills roughly 80 people in the US each year (CPSC), and the operative safety document is CPSC's placement guidance — outdoors only, 20+ feet from the home, exhaust pointed away, never garages or near openings. Nothing on this site modifies that, and no verdict here makes any machine safe anywhere. What we do is clerical: rank on published numbers, and record each generator line's CO-shutoff claim and who stands behind it, with every citation linked. The full CO record is the audit the ranking's per-row CO notes point into.
The four verdicts
- UL 2201 certified — third-party certification to ANSI/UL 2201 (CO shutoff plus reduced CO emission rates), with a public listing in UL's directory (category FTCN). The strongest claim shape: someone other than the seller controls the testing and keeps a record anyone can check. CPSC modeling attributes ~100% death-aversion to this class.
- G300 — manufacturer-stated — the maker cites ANSI/PGMA G300 with an edition (Honda G300-2023, Champion G300-2018). Named and dated, therefore falsifiable — but self-declared: PGMA publishes a standard, not a certification listing. (~87% in the same CPSC modeling.)
- Advertised, no standard — a branded CO-shutdown system (CO-Sense, CO Alert, CO Secure…) with no named standard we could locate. Materially better than nothing; checkable against nothing. Rows here move up the day a citation is published.
- No CO shutoff — no system at all, which per CPSC's own finding still describes most units sold. This tier is the reason the site exists.
Two disciplines we hold
- SKU precision: CO systems ship on designated models, not whole brands — several makers sell sensor and non-sensor variants of the same generator side by side. Rows describe lines; the model number on the box decides.
- A shutoff is not permission: the sensor is a backstop for placement mistakes. We never present any tier as making enclosed-space use survivable, and every page links CPSC's placement guidance rather than paraphrasing it into advice of ours.
Sources we accept
UL announcements and the UL certification directory; PGMA/ANSI standards identification; manufacturers' own system pages and standard citations; CPSC reports, data and the Federal Register rulemaking docket. Retailer listing copy and review-site prose are not sources for verdicts.
How we're paid
Some product links are Amazon affiliate links; purchases through them may earn us a commission at no cost to you. In the ranking, the $/W figure, the sort order and every spec are computed from the maker's published numbers before any link exists; brands without an affiliate relationship (e.g. Predator/Harbor Freight) get an honest untagged link. In the CO record, links appear only on rows with a named standard behind them (UL 2201 or stated G300) — never on advertised-only or no-shutoff rows. A ranking or a verdict can never be bought.
Corrections
If a maker publishes a standard citation, a UL listing appears or lapses, or CPSC's record moves, the dataset changes and the pages regenerate. Every claim links its source — if we disagree with the source, the source wins. Corrections: [email protected].