How Many Air Purifiers Do I Need?

How Many Air Purifiers Do I Need featured photo

If you want to keep indoor air clean, you know how important it is to invest in an air purifier. Still, you may wonder if a single device is enough to improve the air quality of the whole house. “How many air purifiers do I need to enjoy clean air?” is probably just one of your questions.

The exact number of air cleaners you need depends on several factors, such as the indoor air volume and the air purifier capacity (CADR). You can generally have a single device for each room to ensure clean air, but it is not required.

This article will explore the factors that affect the number of air purifiers you need. We will also explain why having more than one device is recommended. By the end of the article, you’ll have a better idea about the ideal number of cleaners for your home.

How Many Air Purifiers Do I Need In My House?

Most homeowners only use a single air purifier to clean indoor air. However, not every household member has the same air quality tolerance level and health condition. For instance, someone might be allergic to pets, whereas another person is sensitive to tobacco smoke but has no problems with animals. You must also consider outdoor pollutants that may enter your home without your knowledge.

Having more than one air purifier enables you to enjoy cleaner air throughout the day. These devices can remove bacteria, chemical smoke, dust, mold, pet dander, and viruses within your house. They ultimately minimize the risk of you getting sick from indoor pollutants.

We recommend one air cleaner per room to achieve the best indoor air quality, especially if it is a big house with high pollution levels. But if you are on a budget or have a small home, you can stick with two air purifiers to clean the indoor air.

How to Determine the Number of Air Purifiers Needed?

While we mentioned the ideal number of air purifiers you need, the exact figure can still change depending on several factors. First, you should understand how indoor air quality is measured. Let’s take a closer look at these considerations below.

Measure the Room Size

The first factor to consider is the room size. It determines the indoor air volume that the purifier will have to cover.

Larger rooms will likely need more than a single air purifier, whereas smaller spaces can get by with only one unit.

Almost all air purifier manufacturers will state the coverage area and overall efficiency of their products. This is expressed in cubic feet.

You just match the figure to your room size. Use this formula to measure the total air volume of your room:

Room Area (Length x Width) x Ceiling Height = Volume

Let’s say you have a room with an area of 500 square feet and a ceiling height of 10 feet. Multiply those numbers and get a volume of 5,000 cubic feet. Basically, the computation would be like so:

500 square feet x 10 feet = 5,000 cubic feet

Now, you’ll need to look for single or multiple air purifiers that can handle this exact indoor air volume to clean air properly. 

Know the Capacity of the Air Purifier

After finding the volume of air that needs cleaning, the next thing to determine is the air purifier capacity. It describes how often the air cleaner replaces polluted air in a room with filtered air. It is usually measured in ACH (Air Changes per Hour).

The ideal air changes can vary depending on the room type and the pollutant levels.

For instance, the recommended ACH in the kitchen is between 6 and 8 because it is constantly exposed to food waste and chemicals.

The living room can bear an ACH rating of 4 to 5.

Finally, bedrooms with a single occupant can manage 2 to 3 air changes per hour.

We recommend contacting a professional to determine the optimal ACH rate for your home. You can also follow the standard guidelines of any organization that regulates indoor air quality, such as ASHRAE.

Calculate the Minimum Clean Air Delivery Rate (CADR) for Your Room

The minimum clean air delivery rate (CADR) is another way to determine the air purifier capacity. It measures how many cubic feet per minute of airborne particles the purifier can remove while cleaning 80% of indoor pollutants during a one-hour cycle. The Association of Home Appliance Manufacturers (AHAM) uses this standard to dictate the efficiency of an air purifier.

The minimum air purifier CADR must be at least two-thirds of the total room area. So if you want to compute the exact clean air delivery rate, you can use this formula: 

Room Area (Length x Width) x (2/3) = Minimum CADR  

For example, your room has dimensions of 10 feet by 15 feet and a total area of 150 square feet. Following the above formula, you’ll need to buy an air purifier with a minimum CADR of 100 square feet. 

150 square feet x (2/3) = 100 CADR 

You can also buy two or more additional air purifiers with a cumulative CADR amount. For instance, you can buy two total air cleaners (each with a CADR of 50 square feet) for your 150-square-foot room.

You can even use an additional air purifier with a higher CADR than your room requires. Doing so enables you to enjoy clean airflow more often and faster. However, avoid going below the recommended rating to prevent poor indoor air quality.

This could vary depending on the use of the space, especially if you’re trying to keep the air clean in a workshop.

Consider the Number of People in the Room

Measuring the CADR alone isn’t enough. You might also want to consider the number of people in the room because it affects indoor air quality.

The more people in the room, the greater the need for air purification. That is because many individuals within one space cause a higher concentration of air pollutants. You’ll need to have more than one air purifier to enjoy clean air within the house.

What Size Of Air Purifier Do I Need?

What Size Of Air Purifier Do I Need

It is essential to buy an air purifier or two that can handle the room size you need to clean. For instance, if you have a 1,000 square feet room, you must choose a large air cleaner that can cover that size. Alternatively, purchase two small air purifiers with at least 500 square feet of coverage to match your room size. Make sure they are lightweight and portable models so that you can easily move them around your home. 

Do I Need An Air Purifier for Every Room?

In an ideal world, you should have a single air purifier in every room. It can remove airborne pollutants that may come from outside, people, and even your pets. It can ultimately provide you with clean indoor air throughout the day.

However, not everyone can afford multiple air purifiers in their houses. It is also unnecessary to place one air cleaner in every room.

Instead, focus on having enough cleaning coverage throughout your house. That means buying the right air purifier that matches your room size, especially in areas where you spend the most time.

Is There Such a Thing as Too Many Air Purifiers?

There is no such thing as having too many air purifiers in your home. The only downside we could think of is the cost of ownership and maintenance.

Otherwise, you can buy as many air cleaners as you want to improve indoor air quality. The more air purifiers, the better. Having several air purifiers can target different types of indoor pollutants. Just make sure you buy a separate kind of air purifier to remove specific contaminants, like so:

  • HEPA (High-Efficiency Particulate Air) Air Purifiers – These have a built-in HEPA filter to remove 99.97% of airborne particles as tiny as 0.3 microns. These include dust, pollen, and pet dander. As such, these HEPA filters are suitable for people with allergies or asthma.
  • Activated Carbon Air Purifiers – They feature an air purifier technology that uses activated carbon filter for trapping volatile organic compounds (VOCs) in the air. They can effectively remove odors from cooking, smoking, and pets.
  • UV Air Purifiers – These air purifiers work by using UV light to kill mold and mildew growth in rooms. However, they are ineffective against VOCs and other smaller airborne contaminants.

How Long Does It Take For An Air Purifier To Clean A Room and Improve Indoor Air Quality?

The exact period it takes for an air purifier to clean the entire room depends on several factors. These include the current indoor air quality, air cleaning efficiency, and room size.

But to give you an idea, an air purifier takes 30 minutes to several hours to clean your room. Invest in an air cleaner with a high CADR to achieve purified air in no time. However, note that a purifier isn’t a one-time solution. You’ll need to operate it continuously to maintain healthy indoor air quality.

Do Air Purifiers Consume a Lot of Electricity?

Most air purifiers have a maximum wattage ranging from 40W to 200W. They don’t consume a lot of electricity compared to other home appliances. So even if you operate air cleaners day and night, you won’t usually see any major increase in your electricity bill.

That said, check the electricity rates in your area because the overall costs can fluctuate significantly. Consider looking for air purifiers that are Energy Star-certified to help save energy and ensure better air cleaning efficiency.


Having one purifier is better than nothing at all. But if you have a large home or a small one with several partitions, you might wonder how many air purifiers you need.

The exact number of air purifiers to own will depend on their capacity, your room size, and indoor air quality. You can have two or more purifiers as long as they provide enough air changes per house and cleaning coverage for the whole house.

Be sure to check out some of our favorite air purifiers for dust removal to help you maintain a clean and filtered home!