What size air purifier do I need? Helpful Tips and Tricks

Modern people make high demands on the convenience of their homes. A healthy environment is a comfortable environment, after all. However, the ventilation systems in many rooms leave a lot to be desired, often causing breathing problems, bad odors, excessive dryness or unhealthy humidity.

In such cases, a good air cleaner becomes the best solution to get the cleanest air. An air purifier is an indispensable device for people with respiratory problems, prone to allergies, or simply intolerant of polluted indoor air.

Air purifiers effectively remove dust, cigarette smoke, unpleasant odors, and pet dander.

Now you may have a question: what size air purifier do I need?

Follow our instructions to get the best air purifier you possibly can!

Why should you use an Air Purifier

Purifiers are not medical devices, but they significantly reduce almost all harmful contaminants and air pollution effectively inside a room space, creating more comfortable conditions for living and maintaining health, relieving our body of unnecessary efforts spent on cleaning the air space using our own respiratory system.

Two interesting facts about air:

  • We consume air continuously, including during sleep. According to scientists’ calculations, the average adult consumes about 20 kilograms of air per day.
  • The air quality in the room is always 20 times, or even more, dirtier than outside, on the street. The only exception here is if your room is almost airtight and you use an air purifier.

By using an air purifier that can do a lot of filtered air changes per hour (especially with HEPA filters!), you will get rid of these harmful substances in your room space:

  • smoke
  • animal hair
  • indoor allergens
  • bacteria
  • mold spores
  • odors of any origin
  • dust mite
  • chemicals, toxic gases
  • pollen

Thus, get the right air purifier for your sq ft to get rid of all those things!

How do you determine what size air purifier you need?

So, what size air purifier do I need? To learn more, use our tutorial and learn how to choose an appropriate size of air purifier for your room!

Step 1. Make measurements

To start up, before choosing a room air purifier you need to determine how many square feet is your room size (or multiple rooms, large spaces and even the whole house in some cases) and the total air volume.

The get your total square footage rating, measure the floor area of your room in square feet with a measuring tape. After that, multiply the resulting total square footage by ceiling height of the room to get the volume of the room. The result will be in square feet. In a case when you need to get the measurements in cubic fee, multiply the previous result in square feet by 35.

This will give you your air purifier room size in square feet.

Step 2. Calculate CADR rating

Now you need to dabble in some maths to get the CADR rating of the room sizes in sq ft to get the air purifier you need. To do that, multiply the resulting cubic feet by 3. This is because room air purifiers clean the total volume of air in one room or other large space 3 times per hour.

This rating is used by home appliance manufacturers to show you the number of cubic feet can an air purifier clean. So, the larger the rating – the larger the volume.

If your room has a tall ceiling, then you can make a workaround without needing to measure the ceiling height. Doing this is simple: you will have to measure the floor in square feet. Then, divide it by 1.55 in sq ft. This is done because your room floor square footage is basically CADR x 1.55 in sq ft.

Now you can get your CADR rating without measuring your ceiling height!

Step 3. Choose the right device

In this step you have to get a device that fits the square feet of your room size space and how much air you have.

Usually, strong air purifiers sport a rating of around 500 to 900 sq ft/hour. If your room has much more sq ft than this, then you should probably buy multiple air purifiers for these sq ft.

Another thing of note is that the CADR in sq ft that is listed on the packaging of an air purifier is for the maximum setting of the device.

This means that the air purifier has to work at its max power for this clean air delivery rate, possibly making a lot of noise and consuming a lot of power.

What is CADR rating?

CADR is basically the indicator showing the amount of air that is cleaned of specific pollutants by one device every minute. CADR rating shows you how good is the air filter at reducing pollutants in your home in cubic feet, and is usually found on the packaging of air purifiers.

Air purifier models can vary greatly when it comes to these rates.

This method shows that the higher the score the air purifier has, the better it will be at keeping your house or office with clean air. Efficient air purifiers usually don’t have a rating below 350.

For instance, the CADR of 120 means that an air purifier is capable of filtering a variety of pollutants at 120 cubic feet/minute. Higher numbers mean a faster indoor air cleaning process of an air purifier.

Initially, this method of air purifier rating appears to be easy and relevant – it gives you a recommended room size in square feet along with a sense of the air purifier’s purifying capabilities. However, this score is not without controversy.

To calculate the air filter performance, researchers place an air purifier in a 3.4m by 3. 4m room with a 2.4m ceiling height. The place of the experiment is completely closed and the pollen test is finished within ten minutes.

Within twenty minutes, the tests for tobacco smoke and dust are complete. Simply because the tests are done in a tiny, enclosed room over a short period of time, the CADR score is likely to promote quick air circulation among air purifiers.

While it is helpful, any air purifier with minimal filtration but high airflow to move air faster scores higher.

That said, air purifiers with filters that capture far more particulate matter but have reduced airflow have lower scores. Many air purifier brands recognize this drawback and maximize the airflow in their air purifier lines.

Can an air purifier be too big for a room?

No, actually it is beneficial to purchase a bigger air purifier! A bigger size air purifier has a stronger airflow compared to a small air purifier and thus is able to purify air inside much faster.

Making a small-size air purifier work in a room with a lot of sq ft will cause the cleaner to work at its top square footage capacity due to this large room size in sq ft. Moreover, this one particular room will probably be the limit of its capacity, as it will not be sufficient in a large room with more sq ft due to its small air changes per hour.

Due to this fact, your small air purifier work might be bound to work only in that one same room.

Many air purifiers that are larger have a number of drawbacks as well. For example, they are way bulkier and require more space and a bigger room size in square footage, which may be inconvenient for smaller habitations with fewer sq ft.

Moreover, many air purifiers that are larger give a higher noise level due to a greater clean air delivery rate, which may cause problems with an air purifier, especially for a small room size in square footage. The high noise level would probably give you sleeping problems.

Lastly, a bigger size air purifier might be costly in terms of energy consumption, which may have an impact on your overall budget. Thus, to save money, you should probably avoid if you have a smaller room size in square footage.

Probably the need to change air filters will arise more often if you buy a larger air purifier size.

So, in the end, the top models of larger air purifiers are more efficient in terms of air purification, but purchasing the right size air purifier for your room size in terms of square footage might be more beneficial in the long run.

Also read our articles How long should you run an air purifier.


Is it better to have one large air purifier or multiple small ones?

Usually, buying only one air purifier is preferable due to its reduced power consumption and quieter operation. In order to clean the air in a single room without working at maximum capacity, it is better to have an air purifier size that is higher compared to your air purifier room size in square feet.

Does the size of air purifier matter?

Yes, the size of the air purifier matters. In terms of air changes per hour, a larger air purifier performs better than a smaller device. However, thas larger air filtration performance requires a lot of energy and generates more noise, which may be detrimental for air cleaners that are placed in bedrooms or other small square footage sections.

Some people use an air purifier in work areas, such as when working with a chainsaw, when a lot of dust is created.

If you know how to apply for Section 8 in Indiana and are moving soon, it is important to know what size air purifier is best for your home.


Modern manufacturers offer effective air purifiers that can provide a comfortable healthy environment in your home, apartment, office, or other space. The most important thing is to correctly select and follow the operating instructions for the air purifier. It just makes more sense.

After that, choose the properly sized device for your room size in terms of the square footage of your room, be it a small bedroom, or a large space. If your friends are planning to buy an air purifier, and ask you “what size air purifier do I need?”, make sure to send them this article!

Monitor air quality – take care of your health and loved ones!

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