What Size Dehumidifier do I Need?

If you’ve decided that you need a dehumidifier to reduce the moisture in your living space, you now need to decide just how big of a machine that you will need. If you are going to properly protect your valuables from excess moisture and reduce the possibility of mold and mildew in your home or apartment, you want to do the job right.

Say good-bye to those dripping pipes, that peeling wallpaper, that warping wood and that horrible musty smell that has hung around far too long in your basement, closet, or other area. You are shooting for a 40-50% humidity rate, which is ideal for the air you breathe and live in.

Sizing Pointers

Here are several pointers as you try to find the right size of dehumidifier to dry the air a bit where you live or work:

  • Dehumidifiers are classified according to the number of pints of water that they will remove from the air during a 24-hour period. They come in sizes ranging from 25 pints to 70+ pints.
  • Obviously, if the air that you are attempting to dehumidify is extremely moist, your dehumidifier will fill up more quickly than in an area where the air is less moist. For instance, a basement that is built below the water line and has persistent excess moisture will fill up a dehumidifier’s tank much more quickly than a unit by the kitchen window. Plan appropriately.
  • Two factors will drive the size of dehumidifier that you buy: the area that you hope to dehumidify, measured in square feet (length X width) and the rating you would give to the dampness in the area that you want to dry.

Sizing Table

That said, here is a handy table to calculate the size of dehumidifier that you will need. The numbers are the amount of Pints that will be collected in the machine during a 24-hour period (all values approximate):

Dampness Level 500 Square-Ft Area 1,000 Square-Ft Area 1,500 Square-Ft Area 2,000 Square-Ft Area 2,500 Square-Ft Area
Moderately Damp
(musty smell when weather is humid)
10 15 20 25 30
Very Damp
(constant musty smell, spots on floor)
13 20 27 34 41
(moisture is very apparent, seepage)
16 25 34 43 52
Extremely Wet
(wet floor at all times)
19 30 41 52 63

Other Factors

Factors that can alter these measurements include: laundry equipment present, the number of doors and windows in the space that you are dehumidifying and the amount of activity in the area that you are trying to dry out.

For example, if there are lights in your basement that are constantly on, it will help to dry the area a bit. Likewise, windows through which sun can stream will lead to a natural drying during good weather conditions that will help your machine’s performance. Doors that let in drier air can also speed up this process.
Conversely, if you are trying to dry an area with a large washer and wet clothes constantly in the room, your machine will fill up more quickly with water.

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