Standards
How we work
Sources, evidence labels, calculations and rankings — the rules behind every page.
Sources
Product figures are transcribed from the maker's own store or product page where one exists, otherwise from retailers' product listings. Each product page lists the pages we used and the date we retrieved them. A product without enough sourced figures is not published.
| Label | Meaning |
|---|---|
| Manufacturer store | Published on the maker's own store or product page for the exact product |
| Retailer listing | Published on a retailer's page for the exact product |
| Wattstanding calculation | Our arithmetic from published figures; the formula is shown |
| Not verified | Reported, but we could not confirm it from a product page |
Runtime and sizing calculations
- Usable energy = capacity (Wh) × 85%. The 85% covers inverter and conversion losses; makers rarely publish an efficiency.
- Runtime = usable Wh ÷ (running watts × duty cycle). Duty cycle is the share of time an appliance draws power (for example 40% for a modern refrigerator).
- Starting watts needed = running total + the largest single (starting − running) surge, assuming motors start one at a time.
- Solar: panel watts × 75% × peak sun hours per day, using approximate regional annual averages.
- Fuel burn = tank size ÷ the maker's stated runtime at the stated load.
Appliance wattages are typical planning values, not measurements. We say so on every page that uses them, and we recommend reading the nameplate on your own appliance. See how we calculate runtime.
Rankings and comparisons
Every best-of list states which products qualify and the single criterion that orders them. Comparisons pair products of the same type and similar capacity or watts, and every difference we state comes from the published figures. Commissions never affect inclusion or order.
Safety
We treat safety as part of the information. Pages about generators explain carbon monoxide and outdoor placement; pages about transfer switches, interlocks and home batteries say that a licensed electrician must do the work. We do not say whether a product is suitable as backup for medical equipment.
Prices and links
Prices are the lowest base-model price listed by the lead seller on the date shown. Product buttons open the product page for that exact model; our link system rejects search, category and home pages. Links are rechecked before publication.
Images
Product photographs come from the product's own store listing and are used to identify the exact model. Each image's source page is recorded. If we can't show an exact-model image, we say "Product image unavailable" rather than substitute another product.
Corrections
Found an error? Email [email protected] with the page and the source. We correct factual errors promptly and update the retrieval date.