About & editorial policy

Why this site exists

Buying a dehumidifier is one of those purchases where the number on the box is doing almost all of the persuading, and almost none of it is comparable. A unit is sold on two figures: pints per day, which comes from a federal test, and square feet of coverage, which comes from marketing. Most buying advice treats those two as interchangeable. They are not remotely the same kind of number.

On top of that, the pints figure itself was redefined in 2019, and most of the sizing charts still circulating were written before that and never updated. The result is that a careful person can follow good-looking advice, buy a unit that looks generously sized, and still have a crawl space sitting at 70% relative humidity in August. That gap is the entire reason Damp Down exists.

🔴 The 2019 rating change, which is most of the answer

In 2019 the US Department of Energy changed the test condition for dehumidifiers from 80 °F to 65 °F. A dehumidifier pulls less water out of colder air, so the same machine, unchanged, now earns a materially lower number. A modern 50-pint unit removes roughly what a pre-2019 70-pint unit did.

Every sizing chart written before 2019 — and most of the ones published since, because they were copied from the old ones — is on the old scale. Follow one with a machine bought today and you undersize by roughly 29%. That is the single most common error in this category and almost nobody names it.

So we do two things. Every figure on this site says which scale it is on, and our calculators return both — the modern number to shop with, and the old number so you can see what a legacy chart or an older machine in your basement is actually claiming. This is why our recommendations come out larger than most, and it is checkable: the rating change is a published DOE rule, not our opinion.

🔴 Square feet of coverage is not a comparable number

The second finding is ours, from the listing data behind this site. As of 21 August 2026, three units all rated at 155 pints per day publish coverage claims of 7,500, 6,000 and 6,000 square feet — and a 160-pint unit, the larger machine, publishes 2,500. Elsewhere in the same data a 113-pint crawl space unit claims 1,200 sq ft while a 125-pint claims 6,500.

There is no standard behind the square-footage figure. Nothing tests it, nothing defines the assumed ceiling height, air changes or dampness, and the spread above is what happens as a result. Pints per day is tested; coverage is a claim. We size on pints per day, we show coverage only with the brand’s name attached to it, and we never rank one unit above another on it.

🔴 What we do not claim

We have never run any of these units in a crawl space. There is no test bench here, no basement full of loaners, no hygrometer logs from a six-month trial. If we wrote that there were, you would have no way of checking it — which is precisely why so many sites in this category write it.

There is no invented expert here. We have not manufactured a friendly HVAC veteran with twenty years in the trade and a headshot. And no invented location: no fabricated head office, no “serving your area since”.

What we trade for giving up those claims is that everything we do assert becomes checkable — the DOE rule, the tested capacity on the listing, the arithmetic in our own source. It is a worse marketing position and a better deal for you.

How a recommendation is actually made

1. The sizing is computed, not looked up. Our calculators take your area, how wet the space actually is, and whether it is a crawl space, and return a pints-per-day requirement on both scales. The derivation lives in one shared file so no two pages can disagree, with the reasoning written into the source — including the crawl space uplift, which we state as our assumption rather than dressing up as a standard.

2. Units are matched on their own tested capacity. We compare a product’s published pints-per-day rating against the computed requirement — like against like, both on the modern scale. Units whose listing contradicts itself on capacity are excluded from sizing entirely rather than quietly averaged.

3. Products are screened on data, not vibes. Listing specifications, verified review counts, sales velocity, whether there is a pump, whether it is built for an unconditioned space. Every ASIN is re-checked before publication, because Amazon listings drift to different models without changing the URL.

4. We read the reviews properly. Not the star average — the most-upvoted verified complaints. That is where the material worth publishing is: the pump that fails before the compressor does, the drain hose that kinks at the bend, the unit that frosts its coil at 50 °F. Competitors rewrite the manufacturer’s bullet points.

5. The recommendation follows a rule you can inspect. Our tools return one unit because a stated rule selected it from your answers. Change your answers and watch the pick change. When the honest answer is that a smaller or cheaper unit clears your requirement, that is the one that comes out.

What this method cannot tell you

It cannot tell you whether a unit is still running in year three, because that needs two years of it running. It cannot tell you how loud one really is — the decibel figure on a listing is measured at an unstated distance under unstated conditions, and a crawl space under a bedroom floor is a different problem from a garage. It cannot tell you what happens when you call the warranty line, which in this category is a real and frequently decisive difference between brands.

Those questions need hands on equipment over years, and we have not done that. When you need that kind of answer, go and read people who have: HVAC-Talk is decades of working contractors arguing about equipment that failed; r/HVAC is the same trade, less formally; and Building Science Corporation publishes free technical papers on crawl spaces, vapour control and why a space is wet in the first place, which is a question no dehumidifier answers.

We earn nothing when you go to any of them. A site that never sends you anywhere else is telling you something.

Where we are, and who we write for

Damp Down is a US-focused publication, not a local business. Prices are in USD, products come from Amazon.com, and every figure uses US conventions — pints per day, square feet, degrees Fahrenheit, and the DOE rating that only exists here.

We do not publish a business address, and we would rather say why than leave a gap. A street address on a national publication signals a local service business we are not, and plenty of affiliate sites invent one because it looks reassuring. We are a small independent site that works through product data and sizing arithmetic, serving the whole country and no particular part of it.

What we do instead is take geography seriously where it changes the answer, because in this niche it changes it a lot. A vented crawl space in the humid Southeast, a conditioned basement in the upper Midwest and a slab house in the arid Southwest are three different moisture problems with three different right answers — and summer dew point, which is what actually drives a crawl space wet, varies more across the US than almost any other climate figure. Where a regional difference matters, our pages say which region.

Corrections

If a number here is wrong we want to know, and we would rather correct a page than defend it. Material corrections are made in place and the review date at the top of the page changes. All pages currently carry a review date of 21 August 2026. Reach us via contact.

Money

We earn Amazon commissions on some links, disclosed in full on our affiliate disclosure page — including the detail most sites omit, which is that Amazon’s cookie lasts 24 hours and pays us on unrelated purchases too. No paid placements, no sponsorships, no gifted units, and no brand has seen a page before publication.