What Size Air Purifier Do I Need?

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Updated February 3, 2023

If you’ve found yourself asking, “What size air purifier do I need?” then you’ve come to the right place. The first step is figuring out what “weight class” you need. There are different categories for sizing, and each one has its limitations. For example, a small kitchen will require much less power and reach than a large living room. However, for an air purifier to be effective, you need to swap your HEPA filter, no matter the size.

These units help improve indoor air quality by restricting pollutants, leading to a healthier home. That’s why an estimated one in four American families has a performing air purifier in their residence. There is a model out there for every home and every room within it.


  • The size of the unit required will depend on the square footage of whichever room you are using it in.
  • Different needs, such as having allergies or owning pets, will change the type of model you should buy.
  • There are four main sizes when purchasing: small, medium, large, and whole-house systems.

Getting the Right Size Air Purifier

There are many different sizes of air purifiers to choose from. We’ll break down the basics of choosing the size that fits your lifestyle in the following sections.

Insider Tip

Humans breathe in oxygen and release carbon dioxide, but plants do the opposite. They absorb carbon dioxide and release oxygen. This works to purify the air.

Small-Sized Units

While the size may vary from manufacturer to manufacturer, you can consider a unit as “small” if it purifies 300 square feet or less of a home. They are most useful for smaller bathrooms and kitchens, children’s rooms, and other modest areas of your home.

Medium-Sized Units

A medium-sized unit is capable of purifying rooms of up to 700 or so square feet. This option will make the most sense for living rooms, garages, dining rooms, lofts, and master bedrooms. You can also use these when traveling in RVs or other mobile living spaces.


As a note, keep the Barberton Daisy in a room that gets plenty of sunlight.

Large-Sized Units

Large units are generally able to clean up the air in rooms of almost 2000 square feet. Typically, these units are used in open-concept living areas, finished basements, or other large, open spaces.

Whole-House Units

Lastly, some air cleaners can work on an entire house. Whole-House units are more expensive and involved to install since they connect to your existing HVAC system. If you have severe allergies or terrible asthma, however, it’s well worth considering.

Insider Tip

As they undergo photosynthesis, many plants release airborne chemicals called phytochemicals. These chemicals are released to protect the immediate atmosphere surrounding the plant, and they do a great job of combating airborne pathogens, volatile organic compounds (VOCs), allergens, and more.

What You Should Consider About Air Purification Systems

There are a few things to keep in mind while shopping. To find the right fit, pay close attention to the topics below.

Reason for Usage

Consider why you need an air purifier. For example, if you have a fireplace, you might need one specifically made to handle smoke and soot. Those with allergies or asthma may want a unit compatible with filters made for those problems. If you have pets, consider the amount of dander you need to filter from the air. They can even be there to help clear the air when cutting onions.

Air Change per Hour (ACH)

Air Change per Hour can seem like a scary metric. However, it simply refers to the amount of air removed from or added to a room. ACH defines how many times per hour an air purifier can clean the air in a room. It is the unit of measurement to reference when figuring out how large of a unit you need to buy.

STAT: In fact, by 2024 the industry is set to surpass $24 billion in worth. (source)

Other things to keep in mind include knowing what the CFM is in an air filter, how to measure a room for an air purifier, how to install a whole-house air purifier, and where to put your new air purifier.

Other supplement info to this includes comparing an air purifier CADR ratings, and how much an air purifier is.

Clean Air Delivery Rate (CADR)

The Clean Air Delivery Rate will help you determine the best unit for your household. The Association of Home Appliance Manufacturers created this official measurement. It is now the industry standard for brands building these machines. Having a CADR is an excellent sign for a unit and helps you better determine whether it is up to the task of keeping your home fresh

If you find this overwhelming and want to go the natural way, you can consider getting plants. Just check out what plants are good air purifiers.


How much noise do air purifiers make?

Most air purifiers are registered between 13 decibels to 36 decibels. The quietest ones can be compared to a faint whisper, with the loudest units are a bit quieter than your average refrigerator. Even the loudest are pretty quiet. This does vary from manufacturer to manufacturer, however.

Should I buy an air purifier or a humidifier?

Air purifiers cannot add moisture to the air. Both are great for different reasons. If you have unpleasant odors, live in a place with air-pollutant, or smoke indoors, an air purifier is the way to go. If you have a preexisting problem with dry air, invest in a humidifier to solve that problem.

Do air purifiers use a lot of electricity?

Not at all. The best estimate is that having one running one at all times costs under $200 a year. Your cost of electricity will only increase marginally.

Are air purifiers a waste of money?

Not at all. In fact, you can expect a plethora of benefits. Here are a few of them:

  • Removal of irritants like pet dander and dust
  • Improved air quality for healthier lungs
  • Less transmission of airborne particles/illness
  • Decrease in environmental pollutant inside

How many air purifiers do I need? One for each room?

This depends on how large your rooms are. You will need to measure the square footage of each room and go from there. If you don’t want to measure your rooms, a small or medium-sized version should provide enough ventilation.

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