We do not test products

No product on this site has ever been in our hands. We are not a lab and we do not pretend to be one. What we do is narrower and, we think, more useful: we take the figures manufacturers publish, put them next to public climate and energy data, and work out what they mean for a specific driveway in a specific place.

That distinction matters most on melt rate. Every portable mat on the market claims two inches an hour. That figure comes off vendor marketing material, not from a measurement anyone independent has made, and it is quoted identically by competitors — which makes it a marketing constant rather than a specification. We use it because it is what exists, and we label it as a claim every single time it appears.

Where the numbers come from

• Product specifications — manufacturer product pages, spec-sheet PDFs and installation manuals. Every record carries its source URLs, and every page that uses a figure links to where it came from.
• Snowfall — NOAA 1991–2020 U.S. Climate Normals, and Environment and Climate Change Canada's 1981–2010 Canadian Climate Normals, for a named reference station per zone.
• Electricity — the U.S. Energy Information Administration's Electric Power Monthly, using the January residential price by state rather than an annual average, because this equipment only runs in winter. Canadian rates come from the utility or regulator tariff directly.

Three rules we do not bend

A blank is a fact

When a manufacturer does not publish something, the page says so. It does not show a category average, a competitor's figure, or a plausible guess. On this site27 of 38 product records have no published wattage, and every one of them says "not published" rather than showing a number.

Volts times amps is not watts

This is the big one, because it is the number the whole site is built on. No mat manufacturer still selling publishes a wattage — HeatTrak, the category leader, gives amp draw only, on every product page and on its own commercial spec sheet. Multiplying volts by amps givesapparent power in volt-amps, which is an upper bound on real power, not a measurement of it. Its own spec sheet also states that the amp figures carry a ±10% tolerance, so even the arithmetic inherits an error band.

So we leave the wattage blank in our data, and where a page shows a running cost derived from volt-amps it shows the inputs, calls the result ours rather than the manufacturer's, and says what it is an upper bound on. We would rather publish a labelled estimate with visible workings than a confident number nobody can check.

When sources disagree, we publish nothing

Two sources giving different figures is not a reason to pick the more likely one. The field stays empty until a primary document settles it. One zone on this site currently has no electricity rate for exactly this reason.

What "verified" means here

A record marked verified has had every figure checked against the source document by a person. It does not mean the model is still current — that is tracked separately, and checked again before anything is written about a product, because a spec sheet on file can describe a product that has since been discontinued or quietly revised.

How pages get written

Pages are drafted with AI assistance and reviewed by a person before publication. Nothing reaches this site without that review; the publishing system rejects unreviewed drafts outright rather than relying on anyone to remember. Calculations are done at build time from the data files, not written by hand into the prose, so a figure in a table and the figure in a sentence cannot drift apart.

Corrections

If a figure here is wrong we want to know, and we would rather hear it from you than leave it up. See corrections for how we handle them.