Choosing the Right Size Dehumidifier

By: Evan Scoboria, Last updated: June 27, 2023

Choosing the right size dehumidifier is critical in effectively managing your home's humidity levels. Not all rooms and spaces are created equal; this discrepancy also extends to their respective moisture levels. To achieve the best possible results, it's necessary to consider multiple factors, including room size and the existing moisture levels. This article will provide a comprehensive guide on selecting the appropriately sized dehumidifier for your needs.

Choosing the Right Size Dehumidifier

Understanding Dehumidifier Capacity:

The capacity of a dehumidifier is an essential factor to consider. It's measured in pints per day (PPD), which refers to the amount of moisture the device can remove from the air within 24 hours.

Dehumidifier capacity is measured in pints per day (PPD), representing the amount of moisture the unit can remove from the air in 24 hours. The Association of Home Appliance Manufacturers (AHAM) has established guidelines to help you choose the right dehumidifier size based on room size and humidity levels:

  1. Moderately Damp (50-60% Relative Humidity): The recommended capacity for rooms with this level of dampness is 10-12 PPD for every 500 square feet. This humidity level typically implies that the space feels damp in humid weather or has a musty smell.
  2. Very Damp (60-70% Relative Humidity): Rooms that constantly feel damp, especially those with a lingering musty odor, fall into this category. A dehumidifier with a 12-14 PPD capacity for every 500 square feet is suggested in these cases.
  3. Wet (70-80% Relative Humidity): Spaces that feel wet and exhibit visible signs of moisture, like damp spots on walls and floors, require a more robust solution. For these, choose a dehumidifier with a 14-16 PPD capacity for every 500 square feet.
  4. Extremely Wet (80-100% Relative Humidity): In cases where space is extremely wet, exhibiting signs such as wet floors and walls, or even seepage, you'll need the most powerful option. A dehumidifier with a 16-18 PPD capacity for every 500 square feet is recommended.

Dehumidifier Size Chart

Choosing the right size dehumidifier can make all the difference in maintaining optimal humidity in your space. Here's a general guideline chart that can be used as a starting point. It's important to remember that these are estimates, and factors like room construction, the number of windows and doors, the quality of insulation, and the number of occupants can affect the actual dehumidifier size you might need.

This chart is based on the Association of Home Appliance Manufacturers (AHAM) recommendations:

Looking at Dehumidifier Options By Size

Large-Capacity Dehumidifiers

Large-capacity dehumidifiers are powerful machines designed to control the moisture level in large spaces or extremely damp areas. They typically have 50 to 75 pints per day (PPD) capacity, making them highly effective for spaces like basements, large bedrooms, living rooms, or whole apartments.

There are several advantages of large-capacity dehumidifiers:

  1. High Efficiency: These machines can extract a significant amount of moisture from the air daily, making them ideal for damp, musty, or water-damaged areas.

  2. Larger Coverage Area: Large-capacity dehumidifiers can cover much larger square footage than smaller units. This makes them ideal for open spaces or multi-room applications.

  3. Advanced Features: Many large dehumidifiers have features such as auto-defrost, continuous drain capabilities, digital humidity readouts, and programmable timers.

However, they also come with some potential downsides:

  1. Higher Energy Usage: Large-capacity dehumidifiers use more energy because they're more powerful. However, look for models with Energy Star certification to help save on electricity costs.

  2. Size and Weight: These dehumidifiers are larger and heavier than their smaller counterparts, which may make them difficult to move around.

  3. Price: Large-capacity dehumidifiers tend to be more expensive upfront. However, they may save you money in the long run by effectively controlling moisture in larger areas or extremely damp conditions.

Whether a large-capacity dehumidifier is correct depends on the space size you need to dehumidify, the humidity levels, and the budget.

Medium-Capacity Dehumidifiers

Medium-capacity dehumidifiers typically have a capacity of 20 to 50 pints per day (PPD), and they are an ideal choice for moderately sized areas, such as bedrooms, small basements, or offices. They balance compactness and power, making them popular among many homeowners.

Advantages of medium-capacity dehumidifiers include:

  1. Versatility: They can effectively handle moderately and very damp spaces of medium size, making them versatile enough to be used in various settings.

  2. Energy Efficiency: These dehumidifiers tend to be more energy-efficient than their larger counterparts. Many models are Energy Star certified, reducing electricity costs over time.

  3. Portability: Although larger than small-capacity models, medium-capacity dehumidifiers are still relatively easy to move around, as many models come with built-in casters.

However, medium-capacity dehumidifiers also have some disadvantages:

  1. Not for Large or Very Damp Areas: While versatile, they may need to be increased for large rooms or spaces with extremely high humidity.

  2. Noise Levels: While generally quieter than large-capacity models, they may still produce noise during operation, potentially causing a disturbance.

  3. Frequent Emptying: If the unit lacks continuous drainage, the water tank may require frequent emptying, especially in high humidity conditions.

Choosing between a large, medium, or small-capacity dehumidifier largely depends on the size of your space and the level of humidity present. It's always best to measure your room and assess the dampness level before deciding.

Small-Capacity Dehumidifiers

Small-capacity dehumidifiers are compact appliances designed to remove up to 20 pints of moisture daily from the air. They're typically suited for small spaces or areas with lower humidity, such as bedrooms, closets, bathrooms, small offices, or gun safes.

Advantages of small-capacity dehumidifiers include:

  1. Portability: These dehumidifiers are lightweight and compact, making them easy to move from room to room. Some even come with handles or casters for easier mobility.

  2. Energy Efficiency: These dehumidifiers generally use less electricity with a smaller capacity, reducing energy costs.

  3. Quiet Operation: Small-capacity dehumidifiers often operate more quietly than larger models, making them less disruptive, especially in spaces like bedrooms or offices.

Disadvantages of small-capacity dehumidifiers include:

  1. Limited Coverage: These units are not designed to handle large rooms or spaces with high humidity and may not be sufficient for basements or large living spaces.

  2. Frequent Tank Emptying: Smaller dehumidifiers have smaller water tanks. If you're using one in a damp area, you may need to empty the water tank more frequently.

  3. Fewer Features: Small-capacity dehumidifiers often come with fewer features than larger models. For example, they may not have automatic shut-off or built-in hygrometers.

Choosing the right size dehumidifier depends on your specific needs and the conditions in your home. Assessing the size of the room, the humidity level, and the desired portability can help you make the best choice for your situation.

Smart Heating and Cooling Systems

Smart heating and cooling systems, also known as smart HVAC (Heating, Ventilation, and Air Conditioning) systems, are innovative technology solutions designed to improve your home's climate control. These systems offer advanced features, such as automation, remote control, and energy efficiency, which make managing your home's climate more convenient and cost-effective.

  1. Automation: Smart HVAC systems can be programmed to follow a specific schedule, adjusting the temperature and humidity levels according to your lifestyle and preferences. Some systems can even learn your habits over time, making automatic adjustments to optimize comfort and efficiency.

  2. Remote Control: These systems usually connect to your home's Wi-Fi network, allowing you to control them remotely through a smartphone app. This means you can change the temperature or turn the system on or off from anywhere, as long as you have internet access.

  3. Energy Efficiency: Smart HVAC systems are designed to be highly efficient, reducing energy usage and lowering utility bills. To avoid unnecessary energy consumption, they can adjust their operation based on real-time conditions, such as the number of people in a room or the current weather.

  4. Integration with Smart Home Devices: Many smart HVAC systems can be integrated with other smart home devices, like smart thermostats, air purifiers, and dehumidifiers. This allows for a more cohesive, efficient, and convenient home climate control setup.

  5. Maintenance Reminders: Smart HVAC systems can also alert you when it's time for maintenance or if there's an issue with the system. This proactive approach can help prevent minor issues from turning into major problems, saving you time and money in the long run.

While smart HVAC systems have numerous benefits, they do require a more significant initial investment than traditional heating and cooling systems. However, the convenience and potential savings over time can make the investment worthwhile for many homeowners.

Our Online Dehumidifier Size Calculator

Choosing the right size dehumidifier for your space can be a complex task, and you need to consider factors such as room size, the level of dampness, and the specific conditions of your space. To simplify this process, we have developed an innovative online tool, the Dehumidifier Size Calculator.

This calculator is designed to recommend the right size dehumidifier for your precise needs. By inputting some basic information about your space, including the size of the area in square feet and the observed conditions (e.g., moderately damp, very damp, wet, or extremely wet), our tool will calculate the ideal dehumidifier size for your space in terms of pints per day (PPD).

Our Dehumidifier Size Calculator incorporates the Association of Home Appliance Manufacturers (AHAM) guidelines, ensuring you get accurate and industry-standard recommendations. The tool is straightforward to use, and it's completely free. You can access it from any device with internet connectivity, providing a quick, reliable reference whenever needed. 

Why Choosing the Right Size Dehumidifier is Important

Choosing the right size dehumidifier is crucial for numerous reasons:

  1. Efficiency and Effectiveness: The right size dehumidifier can effectively reduce the humidity levels in your space, helping to prevent issues like mold and mildew growth, which can harm your health and home. A dehumidifier that's too small won't effectively control the humidity, while one that's too large may result in unnecessary energy consumption.

  2. Comfort and Health: High humidity levels can make your home feel stuffy and uncomfortable. It can also contribute to various health issues, including allergies, asthma, and other respiratory conditions. A properly sized dehumidifier can help create a more comfortable and healthier living environment.

  3. Energy Efficiency: Using a correctly sized dehumidifier for your space can also contribute to energy efficiency. A dehumidifier that's too large for the area may use more energy than necessary, leading to higher energy bills.

  4. Durability and Longevity: Running a dehumidifier that's too small for your space can result in the unit working harder than it needs to, which could shorten its lifespan. On the other hand, a larger unit may cycle on and off too frequently, which can also wear out the device faster.

  5. Cost-Effectiveness: Choosing the right size dehumidifier from the start can also save you money in the long run. You'll avoid buying a unit that's too small (and thus ineffective) only to replace it with a larger one later or a unit that's too large (and thus consumes more energy).

Therefore, understanding your specific needs and the space size you need to dehumidify is essential for making the right choice when buying a dehumidifier. It's not just about picking any dehumidifier but choosing the right size for your needs.

Understanding How Dehumidifiers Work

A dehumidifier is a device that reduces and maintains the humidity level in the air to improve the comfort, health, and longevity of your home and its contents. It works similarly to an air conditioner but focuses on removing moisture instead of cooling the air.

The process begins when a fan in the dehumidifier draws in humid air from the room. This air passes over a cooling coil, a series of cold pipes filled with refrigerant. As the warm, moist air comes into contact with these cold pipes, it cools down, and its ability to hold moisture decreases. This results in the moisture condensing out of the air and onto the pipes. This collected water then drips down into a collection tank within the dehumidifier.

Meanwhile, the now cooler, drier air passes over a set of warm coils, which reheats the air to its original temperature before being expelled back into the room. Cycling air through the dehumidifier continues until the sensor within the device detects the desired humidity level.

Assessing Your Space:

Before searching for the perfect dehumidifier, you must assess your space and understand the factors influencing humidity levels. These factors include:

  1. Room Size: The first step in assessing your space is to measure the square footage. To do this, you multiply the room's length by its width. For instance, a room 10 feet wide and 12 feet long has a square footage of 120 feet. Larger spaces require more capacity dehumidifiers as they have more air to process.
  2. Humidity Levels: Humidity levels can vary significantly depending on your location, the season, and the specific conditions within your home. You can identify the relative humidity in your space using a device called a hygrometer. If the relative humidity is above 50%, you may need a dehumidifier to bring it down to a more comfortable level. Extremely damp conditions, such as those found in basements after a flood, may require a larger-capacity dehumidifier to remove moisture effectively.
  3. Presence of Moisture Sources: Certain areas in your home, like basements, bathrooms, and kitchens, are more prone to high humidity due to moisture-producing sources. Showers, sinks, cooking activities, washing machines, and dryers all produce moisture, increasing humidity in the surrounding air.

For example, suppose you're looking to dehumidify a frequently used bathroom for hot showers. In that case, you'll likely need a more powerful dehumidifier than you'd need for an equally-sized bedroom.

Additional Factors to Consider:

In addition to the basic guidelines, there are some other factors to take into account when determining the ideal dehumidifier size:

Temperature: The temperature of your space plays a crucial role in determining the right dehumidifier. Most dehumidifiers are designed to operate in conditions above 65°F. If your space's temperature consistently falls below this mark, consider a dehumidifier designed to function optimally in low temperatures. This is because dehumidifiers risk icing up when temperatures drop, which can impair their functionality.

Continuous Drainage: Convenience is essential when it comes to maintaining a dehumidifier. Some models come with a continuous drainage feature that removes the need for manual emptying of the water collection tank. They either use a built-in pump to expel the collected water or rely on gravity drainage to discharge water continuously. This feature can be particularly beneficial for spaces with high humidity levels, which would otherwise require frequent tank emptying.

Energy Efficiency: Energy efficiency is another significant factor to consider. Running a dehumidifier constantly, especially in large or extremely damp spaces, can consume considerable energy. To save on energy costs and reduce your environmental impact, consider an Energy Star-certified dehumidifier. These models meet strict guidelines set by the Environmental Protection Agency (EPA) and the Department of Energy (DOE), ensuring they use less energy for the same level of performance as non-certified models.

Fine-Tuning Your Selection:

Once you've assessed your space and determined the recommended dehumidifier capacity, consider the following tips for fine-tuning your selection:

Round-Up: It's always better to err on the side of excess capacity for dehumidifiers. If you're in doubt about the size you need, going for a slightly larger unit can be a wise choice. Why? Because a larger capacity dehumidifier will handle the task more efficiently, often running for shorter periods than a smaller unit. This could save energy costs in the long run and ensures your space is effectively dehumidified, regardless of fluctuating conditions.

Consider Future Needs: Buying a dehumidifier is an investment. If you plan to move to a larger home or remodel your current space in the future, you might need a dehumidifier with a larger capacity. Similarly, if you live in an area where humidity levels can vary significantly across seasons, a larger dehumidifier will give you the flexibility to handle those fluctuations.

Read Reviews: Consider the power of user reviews and expert recommendations. They can provide valuable insights into the real-world performance of a dehumidifier. Look for patterns in reviews: if multiple people mention that a particular model is remarkably efficient, quiet, or easy to use, for example, it’s likely to be a good bet. Also, check how the model performs over time – longevity and durability are essential considerations for such a purchase.


Selecting the right dehumidifier size ensures effective humidity control in your space. By understanding how dehumidifiers work and considering the various factors that influence their performance, you can make an informed decision that will ultimately contribute to a healthier and more comfortable living environment. Whether you require a small, medium, or large capacity dehumidifier or an alternative solution like an air purifier or smart HVAC system, the key is to assess your unique needs and choose accordingly.