Moisture Removal Rate

Test Procedure

To test moisture removal rate we placed each dehumidifier in a sealed 50 sq ft room. We then adjusted the humidity in the room to about 92-94% at a temperatures ranging from about 80° F to 85° F. At this temperature and humidity level the dehumidifier was set to high fan speed and its lowest humidistat setting (in most cases this was 35% or 30%) and was then given a “rolling start” to start dehumidifying from the 92-94% level down past 40% relative humidity.

For the first test we started the timer when the dehumidifier achieved a room humidity level of 90% and stopped the timer when it reached 40%. For the second test we started the timer at 80% relative humidity and stopped it at 50% relative humidity. We then repeated this process at least 3 times for each dehumidifier we tested.

Immediately, we saw what could be approximated as a linear relationship between the initial temperature in the room and how long the dehumidifier took to dehumidify from 90% to 40% RH (relative humidity) or from 80% to 50% RH. Thus we plotted points (starting temp vs time taken) and employed a linear fit in order to normalize values to a starting temp of exactly 82° F for all units. These were the final values used in our analysis of each dehumidifier’s moisture removal rate – the time taken to dehumidify a 50 sq ft room at 82° F from 90% RH down to 40% RH and from 80% RH down to 50% RH.

Note that at 50 sq ft our test space was very small. We used a smaller sized room for two reasons. First, the smaller size of the room allowed us to adjust the temperature and humidity level in the room to levels simulating a severe humidity problem. We wanted to subject our “test subjects” to the most severe conditions we could manage. It would have been much more difficult to achieve humidity levels as high as 90% or even 80% in a larger sized room.

Secondly, because the size of the room was smaller the amount of air that needed to be dehumidified was less, keeping the time taken to dehumidify the room to reasonable levels. For a larger space each test would have taken upwards of several hours. Keeping the test space small allowed us to test each unit multiple times within a reasonable time frame.

Test Results

Our findings were far from surprising. Larger capacity units removed more moisture more quickly than smaller capacity units. Below is the average time (in minutes) taken to dehumidify the test space for each size class.

50 pint11:196:08
35 pint17:238:38
22 pint34:0315:20

Another factor was CFM. Those units with higher CFM fans performed better. Those units with lower CFM fans performed worse. You’ll notice in the comparison chart below that the Frigidaire FFAD5033W1 performed the best in the first test and second best in the second test. This particular model has a distinctly higher CFM than all other 50 pint dehumidifiers on the market today.

Of course there were many other factors that played a role in which units dehumidified our test space the most quickly. Dehumidifier capacity and CFM were simply the most obvious and each of these factors had the most noticeable impact on our results.

Below are our results for all of the dehumidifiers we tested. The heading “90-40%” refers to the time taken (in number of seconds) for the dehumidifier to dehumidify our 50 sq ft test space from 90% relative humidity down to 40% relative humidity. The heading “80-50%” refers to the time taken for the dehumidifier to dehumidify our 50 sq ft test space from 80% relative humidity down to 50% relative humidity.

You can sort the tables below by clicking on the up/down arrows next to each column heading. Clicking on the down arrow next to 90-40% moisture removal rate, for example, will sort the dehumidifiers we tested from fastest to slowest for that particular test. Clicking the up arrow will sort the same units from slowest (most time taken) to fastest (least time taken).

Current Models

Discontinued 50 Pint (70 pint 2012 DOE) Dehumidifiers

Manufacturer and Model
90-40% Test
80-50% Test
Frigidaire FFAD7033R1581281
Keystone KSTAD70B664423
Danby DDR70A2GP608303
Honeywell DH70W561290
GE ADEL70LR699407
Whirlpool AD70GUSB779447
Hisense DH-70KP1SLE827450
Friedrich D70BP782433
SPT SD-72PE688317
Haier HM70EP597311
Delonghi DD70PE771462

Discontinued 35 Pint (50 pint 2012 DOE) Dehumidifiers

Manufacturer and Model
90-40% Test
80-50% Test
Frigidaire FFAD5033R11163557
Keystone KSTAD50B1106536
Friedrich D50BP1083486
Delonghi DD50PE1060473
SPT SD-52PE 1091574

Discontinued 22 Pint (30 pint 2012 DOE) Dehumidifiers

Manufacturer and Model
90-40% Test
80-50% Test
Frigidaire FFAD3033R11948959
Hisense DH-35K1SJE51340630
GE ADEL30LR1847965
Haier DM32M-L30361124

Important Notes

#1 The Haier DE65EM, RCA RDH705, and Kenmore KM70 were disqualified from our moisture removal tests as they could not reach and/or maintain a humidity level at or below 40%. We discuss these dehumidifiers’ moisture removal test results in more detail in our review for each respective dehumidifier.

#2 All times are in seconds. For example “734″ = 734 seconds taken. We had to put all times in seconds to allow you to sort the tables below.

#3 In the charts above you’re looking for those units with the lowest numbers. A lower time means that the unit achieved the desired humidity level faster.

#4 Also note that we have yet to update the average times for each size class that were shown earlier to take into account times for the latest models. When they are added, the average times should remain much the same.


  1. Sheila says

    Next to our thermostat is a dehumidifier. It has 10 settings and it is called Honeywell HumidPRO. I need to know if the Inside Percentage means the percentage of humidity in the house or the percentage of humidity the dehumidifier is taking out. It is cold in here and very sticky, humid. And, should I turn on the fan?

  2. Brad F. says

    Forgive me, I have a hard time fully understanding the mathematical concept relating to a dehumidifier. I just have one question, if the dehumidifier pulls the moisture from the air, but the machine itself creates heat does the entire process drop the temperature in the room it’s dehumidifying?

  3. Jennifer says

    Hi!! I live in a row home in Philadelphia, my basement is approximately 500 square feet ( if I’m measuring correctly) so anyway it was sheetrocked but terrible so many holes. So we ripped it out and put up new sheetrock. It’s basically only storage down there. But I’ve noticed a few winter coats have gotten a little moldy. Can I put a dehumidifier down there to stop this. If so what size? I’m confused about the points part?!? Help!!

  4. Bill hori says

    I have a 800 cubic ft grow room. Been using 35 pint Frigidaire dehumidifier and run it on constantly on. Problem is it brings the humidity level to 65% to 77%. Would like 60% to 70%. Would a larger capacity dehumidifier achieve this ?

  5. Alex says

    Hello – you mentioned “lowest humidistat setting (in most cases this was 35% or 30%)” – could you please let me know which model has a 30% setting available, I am looking for one and most models I see have 35%, but I need 30%.

    Thank you!

  6. Mohamed youssef says

    I have room with 30 m2 and 4,5 m height , the starting temperature 32c and Rh 65% , we ask to get 29% Rh with temperature 25 c , can we reach to our goal without using desiccant system ? Thanks for your effort

  7. Paul Rosenberg says

    This site is amazing, but unfortunately my aptitude for science has always been poor. I did buy the Frigidaire FFAD5033W1 that you rated #1; but I was wondering whether I should run it on “high” for best energy efficiency. Or should I run it high only when the dew point temperature is high (60 +), and medium or low as the dew point gets lower?

  8. Joseph Viggiano says

    We are looking to place a dehumidifier in our bedroom but are on a budget.

    We are fine emptying the basin frequently, but want something that removes moisture out of the air fast.

    It doesn’t appear that there’s a specific metric for that feature, correct?
    It seems that we should focus on CFM and even size?

    Thank you

  9. Kevin Quatrevingt says

    According to this report, you gave the units a rolling start and only ran the timer from the 90% mark to the 40% mark.. do you have the data of how long the “rolling start” was. In other words, how long it took to get from the 92%-94% mark down to 90%. This time period is essential to my specific task , and thus decision making. Are you able to provide the data?
    Please let me know.

    • Admin says

      Unfortunately, no, we did not record exactly how long the “rolling start” was for each unit. We simply made sure the initial humidity level was approximately the same for all units.

  10. Norma Blakney says

    the question I asked was why my dehumidifier keeps running but is not taking any humidity out. it is 84% humidity in my house and no water is in the pan

    • Admin says

      It sounds like your unit is defective. We recommend contacting the manufacturer to further troubleshoot the issue.

  11. SB says

    Midea builds several models for a number of brand names similar to the Keystone model. Many have premature failure on refrigerant leaks (under 2 years). I had purchased a Ecohouzng model (exact specification to the Keystone) due to availability in late 2016. The unit had less than 50 hours of operation when it failed.

    Operational efficiency / testing is only one consideration. Poor workmanship and landfill waste on models that only have a very limited lifespan (seriously, less than 2 years?) is quite another.

    Manufacturers should not be recommended that produce this type of wasteful footprint unless longevity can be significantly improved.

  12. ken says

    I live in the southeast, when we have several days of off and on rain the outside humidity is 100 % the outside temp is 85, the house is new, well insulated, the temp inside is 76, comfortable without AC, but the humidity in the house is in the 90 % range, if we run the AC its too cold, should I be using a dehumidifier, to address the high humidity in the home, the home is on a slab, 1800 sq st, if so what size unit and which would you suggest. Thank you..

    • Mike says

      In your situation I would rund the de-hum, Instead of a/c. A/c must work hard to remove moistue, then thet start to cool. Running a centrelly installed pintergrated with hvac system, will cause the most effient comfort. Like I said an a/c is a poor way to remove moisture. hope that helps. I find a/c’s work less when I have the de-hume runnig. and its more comfotable. If you cannot intergrate a de-hu into you havc system I would get a 70 pint portable de hume with a pump. So it will not shut off, making you empty. You could let the drain into kitc or bathroom sink, that is my set up

    • Admin says

      At this time we do not have any reviews for LG dehumidifiers. We do plan on testing at least one LG unit in our next round-up.

  13. Louise Martindale says

    We have moved into a property that was empty for a year. There was a flood from the attic that soaked a wall in one of the rooms – my son’s bedroom. The landlord had the wall painted but it was still damp and the painted wall has black streaks now. The smell of the paint and damp wall will not go. I have had a large dehumidifier in there for almost 5 weeks. It was collecting 2 buckets per day but is now collecting a quarter of a bucket. Is it safe to use now as my son is in another room?
    What should I use to decorate the damp wall?
    Kind regards,

    • Jacob says

      Louise, the landlord needs to ensure a safe living environment and a wet wall does not make for a safe living environment. Push them to fix the situation or leave. painting over a moldy damp wall is no the solution.

  14. Will says

    Any comparisons involving the hOmeLabs dehumidifiers? I’m considering either their 50pt/6gal or the Frigidaire 6gal model.

  15. Kathryn Keating says

    Hi, we have found a leak in our house, apparently due to the mains water system (and not the heating system). The floorboards warped badly on one bedroom and alot of the floorboards in the rest of the house are starting to warp….Apparently the leak is fixed now (the pipes were routed outside the house), so we have began the process of drying out the house. We hired an industrial dehumidifier, and we are collected 5 litres of water in the “most affected” bedroom every 24 hours. What does this rate mean? We have it hired now and working in the one bedroom for 4 days. From your experience, will this rate decrease or stay steady for another while yet? Many thanks

  16. TOUSIF FATIMA says

    I stay in one bedroom flat .there is a lot of moisture in the house because of that, millipedes enter into my house .so how a dehumidifier can help me in reducing moisture from my house.

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