How we compare

Question first. Every guide answers one buying question, stated in its first lines.

Criteria before picks. We list three to six criteria and why each matters before any product appears. "Best" appears only where a page defines it as criteria; we never name a single winner.

Data sources. Product names, specs and availability come from current Amazon product data, refreshed at every build (at least daily). Facts marked with * in a table, and compatibility facts (which batteries fit which tools, which floors a maker names for a steam mop), come from the makers' own pages, linked under Sources on each guide.

Units. We convert figures to one unit per column (for example torque to ft-lb, tank volume to ounces) with our own arithmetic, and say so. See torque units explained for an example.

When a listing contradicts itself. If a listing states one spec two different ways, the table says "Listing gives two values" and we use neither.

What "not stated" means. If a listing does not give a figure, we say so rather than guess. A column that no listing fills is left out of the table.

No claims of testing we did not do. Our comparisons are research-based. We describe a product as used by us only when we have used it and show our own photos.

Availability. Products that are no longer available are removed at the next build. Pages that fall below their minimum number of available models are rebuilt without product data until reviewed.

Review. Every page passes an automated compliance and copy check, an independent review against our checklist, and owner review before it is published, and is re-reviewed monthly.