Estimate what size dehumidifier you need in pints or liters per day from room area and dampness, using the AHAM sizing chart and typical room presets.

Moderately damp: musty in humid weather. Very damp: always musty. Wet: sweating walls or floor. Extremely wet: standing water.

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Dehumidifier Size Formula

The following formula is used to estimate the dehumidifier size required for a space:

DS = B + K × (A - 500) / 500

Variables:

  • DS is the dehumidifier size (pints per day)
  • A is the area of the space (square feet)
  • B is the AHAM chart size for 500 sq ft and K is the amount added per extra 500 sq ft: 10 and 4 (Moderately Damp), 12 and 5 (Very Damp), 14 and 6 (Wet), 16 and 7 (Extremely Wet). Areas under 500 sq ft use 500.

To calculate the dehumidifier size, start from the chart size for 500 sq ft at your dampness level and add K pints for each additional 500 sq ft. Round up to get the capacity needed in pints per day.

What is a Dehumidifier Size?

A dehumidifier size refers to the capacity of a dehumidifier to remove moisture from the air within a given time period, typically measured in pints per day. The size needed depends on the area of the space and the level of humidity. Proper sizing is crucial for efficient operation and to ensure that the desired humidity level is maintained.

How to Calculate Dehumidifier Size?

The following steps outline how to calculate the dehumidifier size needed for a space:

  1. First, determine the area of the space (A) in square feet.
  2. Next, select the humidity level of the space (HL) from the options provided.
  3. Use the formula DS = B + K * (A - 500) / 500 to calculate the dehumidifier size (DS) in pints per day.
  4. Finally, use the calculator above to verify your result.

Example Problem :

Use the following variables as an example problem to test your knowledge.

Area of the space (A) = 500 square feet

Humidity Level (HL) = Very Damp (2)