Dehumidifiers are an excellent resource for reducing the discomfort felt by high humidity. These appliances can also help prevent mold growth, making them ideal for damp basements or crawlspaces. Dehumidifiers come in a range of sizes, and choosing the right size depends on the tank capacity, the size of the room, the size of the dehumidifier, and the level of moisture in the air.
Use this guide to learn more about dehumidifier sizing, and find out how to determine what size dehumidifier you need for your home.
What Is a Dehumidifier?
A dehumidifier is an appliance that is used to reduce the ambient humidity within a specific area. This typically works by pulling the moist air into the dehumidifier with an internal fan where the air passes over cooling coils to draw the moisture from the air. The water then collects in a removable tank in the bottom of the dehumidifier.
Not every home needs a dehumidifier, so start by inspecting home the for moisture problems. There are several signs that point to high humidity in a home, including fogged windows or doors, moisture accumulation on the walls or ceilings, mold and mildew growth, or excess condensation in high-humidity areas, like the bathroom or kitchen.
If you notice that the air feels damp or it's difficult to breathe inside the home, then there is a good chance that the humidity levels are too high. Ideally, the humidity levels indoors should fall between about 40 to 60 percent in warmer weather and 30 to 50 percent in cooler weather.
To find out the exact moisture level inside the home, consider purchasing a hygrometer. These devices are relatively inexpensive and they can be used to measure the ambient humidity. If you discover that the humidity level is higher than 50 or 60 percent, you should use a dehumidifier to reduce the humidity in the home.
The size of the room or the space where the dehumidifier will be used is one of the most important factors for determining the size of your dehumidifier. Take measurements of the length and width of the space to calculate the square footage. If the room has a ceiling higher than eight to 10 feet, take this extra space into account when selecting a dehumidifier.
Sometimes the only area of the home that tends to get unreasonably humid is the bathroom or the kitchen. If the space you need a dehumidifier for is under 400 square feet, then you can typically stick to a small dehumidifier that is designed for removing 30 or fewer pints of water from the air per day. These units are less expensive than larger models and they tend to operate more quietly. However, the small size of the appliance will generally result in a small-capacity tank, so be prepared to empty the tank frequently.
Most rooms in a home will fall into the medium category, like the den, home office, or bedrooms. These spaces range in size from about 400 to 800 square feet. A mid-sized dehumidifier that can remove between 25 to 50 pints of water per day is the right choice for medium rooms.
While you will end up spending a little more for a mid-sized dehumidifier, the upgrade from a small dehumidifier will ensure that the appliance can effectively reduce the humidity of the space. Mid-size dehumidifiers will generally have a larger tank, so it may not need to be emptied as frequently as the tank in a small dehumidifier.
The average size of each room can differ depending on the home. In some houses, the kitchen, dining room, or living room may range from 800 to 1,200 square feet, making it necessary to invest in a larger dehumidifier. When there are humidity problems in a space this big, you may notice signs of condensation on the walls and ceilings, or even small puddles along the baseboards on hot, humid days.
For these spaces, invest in a large dehumidifier that pulls up to 60 pints of moisture out of the air per day. This will reduce the risk of rot, water damage, peeling paint, and mold growth. Just keep in mind that the larger unit will create more noise than a small or mid-size appliance.
Garage or Basement
In many cases, a garage or basement can exceed 1,200 square feet, and large-capacity portable dehumidifiers are one option. These appliances can typically remove up to 60 pints of moisture per day. Depending on the ambient moisture in the home or garage, this may be enough to get the humidity levels down below 50 or 60 percent.
If the space is prone to high humidity levels that frequently exceed 80 to 90 percent, then a large portable dehumidifier may not be enough. Consider investing in a whole-home unit that can remove up to 155 pints of moisture from the air per day.
In some cases, the moisture problem isn't limited to one or two rooms. If the entire home seems to have recurring high-humidity levels, then you may need a whole-home dehumidifier. These appliances connect directly to the home drainage system, so you don't need to worry about emptying a water collection tank.
A whole-home dehumidifier can be used to reduce the ambient humidity for areas as large as 5,000 square feet or more. These units will pull about 80 to 155 pints of moisture out of the air per day, helping to keep moisture levels low. However, if the home is larger than 5,000 square feet, you may need to invest in more than one whole-home dehumidifier or make sure to buy one that can serve even more square footage.
If the home is located in a humid climate, then the dehumidifier will likely need to work harder to reduce the ambient humidity. Similarly, if the area has multiple doors and windows or if there are water-using appliances nearby, then the unit will need to work harder to keep the humidity levels low.
|Room Size/ Relative Humidity Level||400 Sq. Ft.||600 Sq. Ft.||800 Sq. Ft.||1,200 Sq. Ft.||5,000 Sq. Ft.|
|50 to 60 percent||20-Pint||25-Pint||35-Pint||50-Pint||80-Pint|
|60 to 70 percent||20-Pint||30-Pint||40-Pint||50-Pint||100-Pint|
|70 to 80 percent||25-Pint||35-Pint||45-Pint||55-Pint||125-Pint|
|80 to 90 percent||30-Pint||40-Pint||50-Pint||60-Pint||155-Pint|
The size of the home isn't the only consideration to keep in mind when selecting a dehumidifier. These appliances range in size, including small, medium, and large portable models, as well as whole-home dehumidifiers, which are designed for spaces up to 5,000 square feet in size.
- Small portable dehumidifiers are inexpensive, quiet, and effective for areas that measure 400 square feet or less. A small-capacity unit is generally capable of removing 30 or fewer pints of moisture from the air per day. This is more than enough for a bathroom, small home office, or a large pantry.
- Medium portable dehumidifiers will cost a little more and tend to make more noise than a small-capacity dehumidifier, but they are capable of removing 25 to 50 pints of water per day. Set up a medium portable dehumidifier when the moisture problems are relatively contained to a 400 to 800 square foot area.
- Large portable dehumidifiers are the most powerful option available without resorting to a whole-home unit. These appliances are well-suited for areas that measure about 800 to 1,200 square feet, though a large-capacity dehumidifier may also be a good choice for a large basement or garage. Typically, a large portable dehumidifier will be able to remove up to 60 pints of water per day.
- Whole-home dehumidifiers are designed to reduce the ambient humidity throughout the entire home. Invest in a whole-home dehumidifier if the entire home is having moisture problems or if there is a specific space that measures between 1,200 to 5,000 square feet. A whole-home dehumidifier is capable of removing between 80 to 155 pints of moisture from the air per day.
The frequency with which the tank will need to be emptied depends on the capacity of the tank, the size of the room, and the ambient humidity levels.
If the home only experiences mild humidity problems or if the dehumidifier will only be used in a small room, then the unit doesn't need to have a huge water collection tank. However, if you will be using the dehumidifier in one of the larger rooms in the home or the ambient humidity levels tend to exceed 80 percent, then it's recommended to invest in a dehumidifier with a large capacity tank.
Whole-home dehumidifiers, however, are connected directly to the home drainage system, so you never need to worry about emptying a water collection tank.
What Size Ceiling Fan Is Needed For Each Room?
The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
You Can Control Mold. Centers for Disease Control and Prevention.
Do You Have Too Much Moisture In Your Home? University of Minnesota Extension.
Wolkoff P. Indoor Air Humidity, Air Quality, and Health – An Overview.International Journal of Hygiene and Environmental Health. 2018;221(3):376-390. doi:10.1016/j.ijheh.2018.01.015
What Size Dehumidifier Do You Need?Consumer Reports.