What Size Dehumidifier Do I Need (A Step by Step Guide) | Basement, Bedroom, House, Apartment, and Garage

The size of your dehumidifier depends on the size of the indoor space and humidity levels are in that area. Humidity is a factor that will determine what you need to do with excess water collected from the air. Smaller rooms might only need 30 pints, but larger spaces may require 70 or more! This article breaks down every step for choosing the right size dehumidifier for your needs.

What Size Dehumidifier Do I Need?

  1. Relative humidity rates: Check the room’s humidity level
  2. Square footage: Measure the size of the room.
  3. Average temperature: Measure average room temperature.
  4. Dehumidifier Size: Calculating what size dehumidifier you will need.

Example: A room with square footage of 500 sq ft, a relative humidity of 80% and average temperature of 70°F – will require a 50- or 60-pint dehumidifier.

Step 1. Check the Room’s Humidity Level

A room with high humidity levels, wet surfaces or a musty smell might need a dehumidifier. A dehumidifier will work harder in a really wet space than one that is just damp. You can use a humidity meter to measure the moisture of the room, or you can assess it based on these general criteria:

  • If a space has a musty smell in humid weather or feels clammy sometimes, it is considered damp.
  • If it’s always damp and musty, it’s very damp.
  • If there is visible condensation on the ceiling or walls, it is a wet space.
  • The presence of mold.
  • If a space has condensation or standing water it is very wet.

Note: One way to check the humidity level in your house is to buy a hygrometer at the drugstore. Place it in the room that you want to test and follow the instructions on how to use it. The hygrometer will show you what percentage of humidity there is.

  1. Buy a hygrometer at the drugstore.
  2. Place it in the room that you want to test.
  3. Follow the instructions on how to use it.
  4. Record what percentage of humidity there is.

You should take steps to eliminate or reduce the source of excess water in a room if you detect it.

Step 2. Measure Average Room Temperature

To measure the temperature in a room, you need to use a thermometer. To calculate the temperature in a room, you can also download an app and use your phone’s sensors.

Step 3. Measure the Size of the Room

You will need to measure the size of the room to work out what size dehumidifier you will need for that room.

  1. Measure the length of the room in feet.
  2. Measure the width of the room in feet.
  3. Multiply the two measurements to find the square footage of the room.

Example Room 1: Square Feet Space

If you have a room that is 15 ft long and 20 ft wide the room size will be 300 square feet.

  • 15 ft long
  • 20 ft wide

Room Space = 300 square feet

Example Room 2: Square Feet Space

If you have a room that is 25 ft long and 30 ft wide the room size will be 300 square feet.

  • 25 ft long
  • 30 ft wide

Room Space = 750 square feet

Step 4. Calculating What Size Dehumidifier Do I Need?

Two Dehumidifier Sizing Standards: Used By the US Department Of Energy

When you measure your home, there are two (US DOE)standards for testing a dehumidifier.

  1. Old standard from 2012. 
  2. The new standard was adopted in 2019.

A dehumidifier can be of different sizes. It used to be 70 pints and now it is 50 pints. There was a change in the DOE sizing standard.

In 2012, the standard was based on Energy factors. The 2019 standard is based on the Integrated Energy Factor which is a more accurate way of measuring how much dehumidifier it can do. It also tests the dehumidifiers at a lower temperature (65°F) that the older standard’s testing temperature (80°F).

That’s why both the dehumidifier size chart and dehumidifier size calculator include both old and new capacity.

After 2022, only the new standard will be used.

AHAM Dehumidifier Sizing Table

Humidity Levels:300 sq ft space500 sq ft space800 sq ft space1,200 sq ft space
50-60% Humidity30 Pint (Old Standard)
20 Pint (New Standard)
45 Pint (Old Standard)
30 Pint (New Standard)
60 Pint (Old Standard)
40 Pint (New Standard)
70 Pint (Old Standard)
50 Pint (New Standard)
60-70% Humidity30 Pint (Old Standard)
20 Pint (New Standard)
45 Pint (Old Standard)
30 Pint (New Standard)
60 Pint (Old Standard)
40 Pint (New Standard)
70 Pint (Old Standard)
50 Pint (New Standard)
70-80% Humidity40 Pint (Old Standard)
25 Pint (New Standard)
50 Pint (Old Standard)
30 Pint (New Standard)
65 Pint (Old Standard)
45 Pint (New Standard)

80 Pint (Old Standard)
55 Pint (New Standard)
80-100% Humidity45 Pint (Old Standard)
30 Pint (New Standard)
60 Pint (Old Standard)
40 Pint (New Standard)
70 Pint (Old Standard)
50 Pint (New Standard)
90 Pint (Old Standard)
60 Pint (New Standard)

Dehumidifiers can remove water from the air. The difference is how much water it can remove per day. You can get a small 30-pint, medium 50-pint, or strongest 70-pint dehumidifier.

A pint is a unit of measurement. It’s not as big as a gallon, but it still amounts to 1/8 of that. A 70-pint dehumidifier can take 9 gallons of water out of your house or basement each day.

Read more: How do I calculate dehumidifier?

How big a dehumidifier should you buy?

This is a table of the Association of Home Appliance Manufacturers. There are a few things you will need to know about your home before you can read the table. You will need to know how many sq ft it has, and how humid those spaces are.

If you have a 500 sq ft basement and it has medium humidity (70%-80%), you would need a 50-pint dehumidifier to lower the moisture levels. That’s a ballpark figure.

Note that some people might say 3,000 sq ft or 4,500 sq ft but you should not listen to those numbers.

What Size Dehumidifier Do I Need for a Basement?

In some basements, there is too much moisture, high relative humidity, and high average temperature. That can make the basement have high moisture levels, where mold and spores grow. It can also make the house’s walls weaker over time and put the whole house at risk.

Check or guide on the best dehumidifier for basement.

  • Square footage: 500 sq ft.
  • Relative humidity: 80%.
  • Average temperature: 70°F.

If we look at the table, we can see that the basement with these specifications would need a 50- or 60-pint dehumidifier (according to the old standard) or a 25-30 pint one (according to the new standard).

When you have a choice between two sizes of dehumidifier, always pick the bigger size. It is better to have a more powerful dehumidifier than one that does not work well.

The AHAM sizing chart does not consider the average temperature. If you have a cold basement, you are going to need to add 10 pints for every cubic feet.

What Size Dehumidifier Do I Need for a Whole House?

These are the sizes of a small house:

  • Square footage: 1200 sq ft.
  • Relative humidity: 65%.
  • Average temperature: 70°F.

We can deduce that a house of this size would need a 70-pint dehumidifier (old standard) or 50-pint dehumidifier (new standard). For larger spaces, you might want to consider the high capacity commercial dehumidifiers.

Large Spaces More Than 2,500 Square Feet

If you often deal with excess moisture and humidity and see things like mold or experience musty odors, you need a whole-house dehumidifier. This is ducted to your HVAC system. It gets rid of the moisture before it can come into your home.

Whole-house dehumidifiers cover a lot of space (3000 sq. ft. or more). The first price is higher, but it will cost less in the long run. They also help your AC work better because when the air is dry, it cools better.

Small Spaces Between 100 and 250 Square Feet

In small rooms, it is hard to fit a large 70-pint dehumidifier. That’s why we recommend the mini one.

Mini dehumidifers work quietly and they can cover 100-300 square feet. They work when the room is the right size.

Mini dehumidifiers are small and easy to use. They can fit in bedrooms, children’s rooms, or nurseries. They hold a few pints of water. Most mini dehumidifiers will also turn off when the tank is full.

Homeowners like mini dehumidifiers in their bedroom. These are small and quiet. They don’t have a noisy compressor. Instead they use thermoelectricity.

Cool Environments

If you live in a cold environment, it is best to not buy a dehumidifier because they won’t work. The coils might freeze and then the whole thing doesn’t work anymore.

Note: Refrigerant dehumidifiers cannot work in cooler temperatures. When the temperature is below 60 degrees Fahrenheit, there is a risk of ice forming on the coils. The dehumidifier will waste energy and if left, it can get broken from inside.

Desiccant dehumidifiers are a way to solve the humidity problem. They have a rotor that is filled with sheets that will take out moisture in the air. The air is pulled through with a fan, and then it goes past the sheet with desiccant material on it.

Furthermore, desiccant dehumidifiers are quieter than other ones. They’re also more energy-efficient and effective at drying already dry air.

Hot Environments

If you live in the south, the humidity might be high. You will want to get a dehumidifier. The best kind of dehumidifier for this is one that takes refrigerant (because it can remove more moisture and work in higher temperatures).

Refrigerant dehumidifiers pull the air in through a fan and then cool it on a set of coils. The refrigerant liquid is pumped through the system, converting between gas and liquid form as it cools and heats.

There are other things to think about.

There are many things that can make the humidity in a home higher than normal. These include:

  • Humid climate: If you live in a place that is already humid, the humidity inside your house will be higher. It is recommended to add 10 pints to your dehumidifier. For example, if you want 50 pints of water from the dehumidifier, then get 60 pints instead because there is high humidity.
  • Nearby washer or dryer: If you live in a smaller, humid apartment or townhouse, the washer and dryer might be close to your living space. This can make the humidity go up – add 5 pints. So if you have a 10 pint dehumidifier, try 15 or 20 instead.
  • Will the dehumidifier be in the kitchen: You might want to add 5 pints of water to the dehumidifier in your kitchen. When it’s humid, the humidity can go up there.
  • AC: Air-conditioners and dehumidifiers work the same. They can help each other. If you use air conditioning units during the summer, buy a slightly smaller dehumidifier because it will save energy. The two appliances will work together to create a dry and cool environment.
  • Pets: Pets have fur and they get too hot in the summer. Dehumidifiers make it easier for them to stay cool.

Frequently Asked Questions

Is It Possible to Use a 70-Pint Dehumidifier When Only 30 Pints Are Required?

It is possible to use a 70 pint dehumidifier. It will not hurt you or the room, but it may be loud in small areas. If you have a large dehumidifier, it will make the room drier faster and save energy.

Is it better to get a bigger dehumidifier?

Theoretically, yes. But here’s why: A larger dehumidifier will work more quickly at drawing moisture out of the air, so you can turn it off sooner. This means that it will save more energy.

On the other hand, larger dehumidifiers are usually very loud. If you have a small bedroom, it might be too loud to run a 70-pint unit while you’re there.


With these four steps, you can figure out the size of dehumidifier that is right for your room and how to measure humidity levels in a space. If you have any questions or need help with figuring out what size dehumidifier will work best for different rooms, contact us today! We are happy to answer all of your questions and provide expert guidance on finding the right equipment for your needs.