What Size Dehumidifier Do I Need for My Basement?

Choosing the right humidifier size for your basement depends on your home’s size, temperature, and humidity levels. In this quick guide, we’ll explore the key considerations to help you decide when buying a new dehumidifier for your basement. 

How to Calculate the Dehumidifier Size for Your Basement

Dehumidifiers are rated based on how many daily pints (a unit similar to the gallon or liter) of humidity they can extract from a basement or any other room. The bigger the room, the more humid it is, and the colder it is, the larger the dehumidifier must be to dry it out. 

1. Check Relative Humidity Levels

Relative humidity (RH) is the amount of moisture in the air at a certain temperature compared to the maximum amount the air can hold. It’s measured as a percentage, with higher numbers indicating a more humid environment. For precise measurements, consider using a hygrometer. 

2. Measure the Temperature

Temperature influences the size of the dehumidifier you need. Dehumidifiers work best in warmer basements. Most refrigerant dehumidifiers operate at approximately 41°F, but their efficiency can drop at lower temperatures. Therefore, if your basement is cold, you might need a larger dehumidifier. 

3. Calculate the Basement’s Size

To calculate your basement’s size, multiply the square footage by the height of the ceiling. However, since most basements have a standard ceiling height, the square footage alone is often enough for a good estimation.

Find Your Humidifier’s Size

Now that you have the necessary measurements, you can use the following table to estimate what size dehumidifier your basement needs. This table is based on the 2020 Dehumidifier Testing Standard, which assumes a room temperature of 65°F.

Relative humidity (%)	Basement size (square feet)
400	600	800	1200
50 – 60 (Slightly damp)	20-pint	25-pint	35-pint	50-pint
60 – 70 (Musky smell)	20-pint	30-pint	40-pint	50-pint
70 – 80 (Wet spots on the walls)	25-pint	35-pint	45-pint	55-pint
80 – 90 (Excessive moisture)	30-pint	40-pint	50-pint	60-pint

Remember, these recommendations are estimations. The size of the dehumidifier you need may vary based on the specific conditions in your basement. Consider a dehumidifier with a drainage spout to avoid manually emptying the container daily for highly humid basements or basements requiring frequent dehumidification.

Other Factors to Consider the Size of a Dehumidifier

Besides humidity and basement size, these are other factors that might affect the size of the dehumidifier you’ll need:

• Consider Ventilation. Basements with poor airflow make it more difficult for the dehumidifier’s ability to remove moisture from the air, reducing its performance. If your basement has poor ventilation, you may need a bigger dehumidifier than estimated or invest in ventilation equipment.
• Address Additional Moisture Issues. Basements are notorious for their tendency to become moist from sources like foundation cracks, pipe leaks, plumbing fixtures, poorly sealed windows and doors, and other sources. While the dehumidifier will reduce humidity, it cannot fix the underlying problem.
• Check Insulation. Insulation influences your basement’s ability to retain temperature, high or low. If you live in a cold area and your basement isn’t insulated, you may need a contractor to protect your basement for your dehumidifier to perform up to its maximum potential.

Best Dehumidifiers for Basements

GE 50-Pint Dehumidifier With Pump – Best Overall ($335)

• Great performance and versatility make it the best choice for most basements.
• Covers up to 4,000 square feet.
• Great for large-scale dehumidification during the rainy season.
• The wheels and handle made it easy to move.
• It has a built-in pump with a hose for continuous drainage up to 16 feet away. You can also manually empty the container.
• Its coils auto-defrost when temperatures are below 32°F.

Frigidaire 50-Pint Dehumidifier – Best for Basements with Living Spaces ($315 – $370)

• Comes with an accessible water bucket and a washable air filter.
• Built-in pump for continuous drainage to a location up to 15 feet away.
• Not suitable for temperatures below 40°F since it lacks a frost control sensor, which automatically shuts off the unit when ice crystals start forming on the coils.
• Its lack of frost control makes it better for climatized living spaces than cold basements.

Honeywell 50-Pint Dehumidifier – Best for Large Basements ($300)

• Capacity of up to 70 pints, depending on the model.
• Energy Star-certified for efficient moisture control and low electricity usage.
• Front-facing bucket with a handle makes it easy to dismantle and clean.
• User-friendly interface.
• An accurate humidistat maintains consistent humidity levels during operation, avoiding noticeable changes in basement humidity.
• Built-in pump for continuous drainage up to 15 feet away.
• It can be noisy, so it’s best for storage or unfinished basements rather than living spaces.

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