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What Size of an Air Purifier Do I Need?

If you were thinking about purchasing an air purifier for your home, how would you find out what size you needed? This article will go over various home sizes and walk you through each step to find the best fit for your space.

The size of the air purifier you need depends on what room you’re looking to purify. Your air purifier’s Clean Air Delivery Rate (CADR) should be identical to two-thirds of the room’s area. AHAM (Association of Home Appliance Manufacturers) recommends a smoke CADR proportion to the size of the room in square feet. 

What Size Air Purifier Do I Need?

If you’re wondering what size of an air purifier you need, the good news is that it’s pretty simple to figure out. You only need to take some measurements and do a little math. Here’s what you need to know to get the correct sizing:

  1. Consider Where In The House You Want To Place Air Purifier 

This will let you know how big of a unit you’ll need. So, if you want to put it in a tiny room, like a bedroom, you’ll need a smaller unit than if you’re going to put it in an entire apartment or house.

  1. Measure the Square Footage

Once you’ve determined where to place the air purifier, you can measure the square footage of each room and add them together. 

Formula: Length x Width = Square Footage

When your room is 20 feet long and 15 feet wide, multiply those numbers and get 300. A 300 square foot air purifier is large enough for that room. 

For example, a 20′ x 15′ room = 300 sq. ft.

  • Measuring Multiple Rooms

If you are trying to clean multiple connected rooms, measure the length and width of each room separately and add up the totals.

For example, you have a kitchen (20′ x 30′) with a living room (15′ x 20′) adjoining it.

In this case, your kitchen area would be 600 square feet (20′ x 30′), and your living room area would be 300 square feet (15′ x 20′). Add those together, and you get 900 square feet.

Total: 600’ + 300’ = 900 sq ft.

  • Measuring an Entire House

If you’re purchasing an air purifier for an entire house, including the total square footage since air purifiers are rated by how much space they can clean.

For example, if your house is two stories and has 800 square feet on each floor, multiply that by the number of levels your house has.

Total: 800’ x 2’ = 1,600 sq ft.

  1. Check the Square Feet Rating on the Air Purifier to Your Room

A general rule is that an air purifier with a higher square feet rating is better. However, this doesn’t mean that you always buy the largest Purifier available.

We recommend matching your Purifier to your room’s square footage as closely as possible to distribute the new air it’s producing throughout your whole space. It needs to be big enough to do its job.

Can an Air Purifier Be Too Big for a Room?

Can an Air Purifier Be Too Big for a Room?

The best way to pick out an air purifier is to look at the coverage area of the Purifier and match it up with the size of the room you want to clean. If the room is smaller than the coverage area, you won’t have a problem (and might even notice faster results).

But can you have a cleaner that’s too big for a room? Well, sort of… but not really. If you decide to put it in your living room, about 1,000 square feet. That means that your living room is about a third of the size of the maximum space this Purifier can cover in one cleaning cycle.

For example, if you have a 4′ x 6′ room with a ceiling height of 8′, you’ll want an air purifier with a CADR rating of around 100 CFM. Likewise, a 5′ x 7′ room with 10′ ceilings will need approximately 150 CFM. These numbers will help you find an air purifier to keep up with your breathing rate and maintain good indoor air quality.

What is CFM?

The CFM is the amount of air that the unit can cleanse each minute, and it’s usually a higher number for more giant air purifiers.

Can an Air Purifier Be Too Small for a Room?

Yes. The size of the room and the specifications of the Purifier should be a good match. You’ll want a rated purifier to handle a room at least double in volume to the one you’re trying to purify.

For example, if you’re trying to clean out a 10’x10′ foot room, your air purifier should be able to handle a 20’x20′ foot room. Smaller cleaners will often cover less than half the intended area, while larger ones may waste energy by filtering more air than there is an immediate need for.

Is One Air Purifiers Enough?

The answer, according to experts, is no. A single air purifier is not enough to clean the air in most homes. It is because it’s difficult for a single unit to circulate through all of the rooms in a house.

If you want to purify ample space like an open living room and a kitchen area, a single air purifier may not be adequate. Instead, you may need a few—one for each room—to ensure that all areas of your house are being cleaned properly.

However, if you don’t have a ton of money to spend on air purifiers or only have one small room that needs to be purified, then one may be enough! Or perhaps two: one for the main room and one for smaller spaces like bathrooms or bedrooms.

Example Room Size for Air Purifiers

We usually recommend following this rule of thumb:

Room Size (sq ft) Air Purifier Size (sq ft)
150 150-300
200 300-400
400 400-600
500 600-800
750 800+


Air Purifier Room Size Guide

Small air purifier: A small air purifier is typically used in rooms between 100 and 200 square feet, like a dorm room or office.

Medium air purifier: A medium air purifier is typically used in rooms between 200 to 500 square feet, like a kitchen or main bedroom.

Large air purifier: A giant air purifier is typically used in rooms over 500 square feet, like a great room.

Whole-House Air Purifier: Whole-house air purifier is attached to your furnace and HVAC system so it can clean the entire home.

Best for 200 sq ft Room: Air Doctor 1000 

AirDoctor 1000 Review These days with the raging COVID-19 pandemic you want to ensure that your family is breathing in only the cleanest air possible. This is why you would want to use an air purifier like the AirDoctor 1000 that will give you healthy and pure air to breathe in. You don’t have to worry about catching the COVID-19 virus if you are using the purifier in the right way and if you are making the best decision. When it comes to deciding which air purifier is the best you need to know everything about the model that you are looking at like the AirDoctor 1000. You want to know the pros as well as the cons and everything about the design, placement and how it works. If you want to know more, then go ahead and keep reading on to learn about this new model that can keep everyone healthy and safe. This is our complete and comprehensive guide and review of the Air Doctor 1000, so don’t be afraid to use this to help you make your decision. We will be covering all aspects of the machine from top to bottom, including the inside and much more. Pros There are numerous pros that you are going to want to consider when it comes to this model, such as: • Lightweight • Portable • Long power cable • Sleek and elegant design • Affordable • Perfect for smaller rooms • 4 fan speeds • Control panel is on top • Easy to use • Ideal for those suffering with allergies • Can remove COVID-19 and other viruses from the air These are just a few of the many pros that come along with purchasing this machine, so make sure that you know what they are. If you are aware of these, then you can use them as a deciding factor when making your final purchase. Cons You also need to be aware of a few of the cons that this machine would have. The more you are aware of, then the easier the decision would be and these include the following: • Not ideal for larger rooms if you want the air cleaned more than 2 times an hour • Requires 6” gap around the entire device to work properly • Filters can be expensive • No handles for moving it around One should always be aware of the various cons that any machine might have, then you can be fully informed, which always helps your decision. Go ahead and make sure to compare these cons to the others that any other model that you are looking at might have. Design, Size and Placement If you are looking for something that is going to be elegant and easy on the eyes, then the Air Doctor 1000 is perfect for your needs. You can easily place this in the corner of any room without having to worry about it looking out of place and it can fit into small areas. However, this would be ideally placed in the corner so that the air can be pulled in and pushed out through the vents on the outside. This model measures 9” wide by 9” and is 23” tall, which means it is compact and ideal for smaller rooms. It weighs around 10 pounds and has a voltage of 120V or 60Hz and there are 4 different speeds you can pick from for the fan. This is also going to be very easy to carry since it is lightweight and you can move it from room to room as required. The cable length is 6 feet so you can easily move it in any direction from the plug. This would be ideal to be used in your bedroom or even the office where you need some clean air. It should be placed at least 6” away from the walls in any direction so that there is enough air that it can pull in and the vent needs to be facing to the outside. You shouldn’t block any of the sides since the air quality control sensor is on the side and the touch panel is on the top, which makes it easy to access no matter where you place it. How Does Air Doctor 1000 Work and What Sources of Indoor Pollution it Destroys? This machine works using a high-powered filtration system that pulls the dirty air inside and then pushes it through the carbon activated filter and the medical grade filters. It has 4 fan levels that you can pick from that would allow you to determine just how much air you want to be pushed out. There are various filters that make sure that even the smallest particles are removed from the air so that you don’t have to inhale or be bothered by them. There are numerous pollutants as well as viruses that the Air Doctor 1000 can get rid of in your home. If you are worried about your family getting sick or if you suffer from severe allergies during the spring and other times, then you want to know if this machine would work for you. You should know what can easily be removed from the air by this system, such as: • Bacteria o Staphylococcus albus 8032 o Escherichia Coli 8099 o Staphylococcus aureus ATCC 6538 o Aspergillusniger ATCC 16404 o Candida albicans ATCC 10231 o Klebsiella pneumoniae ATCC 4352 o Serratia marcescens ATCC 14041P o Aeruginosa ATCC 15442 • Viruses o E. Coli Phage Phi-X174 o Influenza A virus A/PR8/34 H1N1 The air purifier has been tested independently and it has proven it can get rid of 99.99% of all these pollutants along with viruses that might cause you go get ill. It uses the H13 UltraHEPA filtration system that is medical grade. These are tested independently in a laboratory and they can trap 100% of any particles that are 0.003 microns in size, which is much more effective than any other HEPA filtration system. Also, it has been tested for the removal of COVID-19 or SARS-CoV-2 and the surrogate virus and it was proven 99.99% effective. It can also remove the Swine Flu or H1N1 virus, which is also called Influenza A Virus A/PR8/34 under the required FDA guidelines. This means that this is going to be highly efficient in removing any traces of the viruses that would infect you and make you ill. Key Features This is a compact model, but that doesn’t mean that it is lacking in any features that you might want to have in an air purifier. Some of the top features that you must be aware of includes: • Medical grade UltraHEPA filters – This filtration system is around 100 times more effective when compared to the ordinary HEPA filtration systems. This one can collect a wide variety of pollutants and allergens, such as: o Dander and pet hair o Cigarette smoke o Mold spores o Pollen and dust It can also capture various types of germs and it can help with reducing the airborne germs, viruses and even bacteria. • VOC filter/gas trap – The HEPA filtration system is going to be paired with the proprietary filter that is dual action with carbon and is a gas trap and VOC filter. This can get rid of a few different things from the air, including: o Toxic fumes o Volatile organic compounds or VOC and gases, such as formaldehyde o Dangerous ozone This is great if you are looking for a complete filtration system that will keep all viruses, bacteria and germs from getting into your system. • Auto mode – This model also has an automatic mode that is used with the sensor for air quality detection. When it detects a lower air quality, then the automatic mode would turn on so that the filtration can be adjusted to clean the air properly. • Filter change alert – You don’t want to be stuck with an air purifier that doesn’t work because the filters haven’t been changed. If you don’t want to worry about remembering when you changed it last or when it might need to be replaced, then this one has a filter alert. This indicator will let you know when the filter must be changed out so you can replace them or place an order for new ones. • WhisperJet fans – The model also has the exclusive quiet WhisperJet fan system to keep the noise level to a minimum. This would allow you to use the highest fan levels without having to worry about the noise being too much, especially if you are using it while you are sleeping. • Sealed system – The final feature to be aware of is that this system is completely sealed, which means that the bacteria, viruses, germs, pollutants and allergens that are collected are sealed inside. You don’t have to worry about them escaping through any means, so the air that you are getting is filtered and pure. It is important that you are aware of these features when you are looking at which one you are going to want to buy. There are so many things to consider, so make sure that you are looking at these and comparing them to the other models before you decide. Noise level You also need to consider the noise level when it comes to the air purifier that you are going to have in your home. If you will be using it in your bedroom, then you want something quiet and this model has a noise level of 34 dB when used on the lowest level. This means that it would be great for going to sleep or even for using in your office if you need something quiet. There are 4 fan levels that would increase or decrease the sound level based on the one that you choose. The highest noise level this creates is 54 dB, which means it isn’t overly loud and you can easily place it in the living room without worrying about a thing. Make sure that you are thinking about how quiet this machine can be when you are trying to decide if this would be the best model for all of your requirements. CADR, ACH, Room Coverage The CFM or CADR for this model is 152 for smoke, 162 for dust and 152 for pollen and it has 4 fans that are ideal for usage in different areas of the home. This would be great since it can easily get rid of the various smells that would come along with pets or even smokers. You don’t need to have a big machine to use in your home, but this one can be placed in the various rooms and if you want you can move it around as needed. Another thing you need to know about is the room coverage for the purifier and this one can handle a room of around 587 square feet. If this is placed in a larger room, then it can clean the air around 2 times every hour, while if you put it in a room of around 235 square feet, then it can clean it 5 times every hour. This would be ideal to be placed in your laundry room, home office, small bedroom or even the nursery where the air should be clean. Maintenance and Upkeep Another thing that you must consider is the maintenance along with the upkeep of this model, which means how often you need to replace the filters. Both the VOC and carbon filters along with the UltraHEPA based filter should be changed out every 6 months. This is ideal and you don’t have to keep track of how long it has been since you will get an alert from the indicator light telling you when it is needed. You should also make sure that with upkeep that you are wiping the machine down regularly to keep all of the dust from building up on the outside. If you don’t do this, then the areas where the vent and the air quality sensor are won’t operate properly. This just needs to be done with a slightly damp cloth so that all of the debris and dust can be picked up and removed from the areas. You can also use a vacuum to get rid of the dirt if you want to get the job done faster. Frequently Asked Questions • How many filters and what types does the Air Doctor 1000 have? This model has 2 filters, which includes the pre-filter that is built-in on the UltraHEPA filter. It also has the VOC and carbon filter that are separate, so make sure that when you replace them that you are buying both of the filters for best usage. • How much power does this model consume? The amount of power that would be consumed is directly dependent on the fan speed that you are opting to use. The lowest fan speed consumes only 7 watts of power while the highest fan consumes some 40 watts. • Can I use this model 24/7? Yes, this model can be used 24/7, but you should make sure to turn it off if you aren’t going to be home. This would ensure that the filters would last longer and you won’t burn out the machine if required. Also, make sure that you are turning it off when you are leaving for longer periods of time for vacations or other reasons. • How do I know what the air quality level is? There is an indicator that uses different colors to help make this easier for everyone. If the light is blue, then the air quality is good and the lowest fan can be used. However, if it turns orange, then it is moderate air quality and the medium fan should be used and if it is red, then the highest fan speed is turned on due to the poor quality of air. • How often do the filters need to be changed out? One main question people always have is how often do I need to change the filters out. If you are using the device 24/7 without any breaks, then the minimum period between replacement is around 6 months. However, there is an indicator light on the device that will let you know if it needs to be changed out sooner or if you can go for a longer period in between. • What allergy symptoms can this device help me get rid of? If you are suffering from allergies and are considering purchasing an air filter for that reason, then there are different symptoms this can help relieve. Some of them includes wheezing, sneezing, itchy nose, throat and watery eyes, hives, itchy skin, runny nose, coughing, nasal congestion and much more. Final Thoughts It is extremely important that you are thinking about which air purifier is going to work the best for your needs. The Air Doctor 1000 is perfect if you don’t have a large budget, but if you want something that would be ideal for your home. This model has a sleek and elegant design that would be suitable for your office or even the kitchen in your home without affecting the décor or style.

This is a compact unit perfect for smaller spaces. Circulates the air in 285 sq. ft. 4x/hour or 570 sq. ft. 2x/hour.

The AirDoctor 1000 is an excellent choice for those looking to purify the air in a 200 square feet or smaller room. It’s an attractive, compact device that won’t take up too much space in your home and is available in 4 different colors: blue, white, black, and grey. It has been rated 4-stars by consumers on its Amazon listing and comes with a 5-year warranty.

Air Doctor air purifier has state-of-the-art technology and can cover more space than many other air purifiers of its kind. It uses four technologies to keep the air clean and healthy in your home: HEPA filters, an activated carbon filter, an ionizer, and a UV light.


  • Medical grade UltraHEPA filters
  • VOC filter/gas trap
  • Auto Mode
  • Whisper Jet fans
  • Sealed System
  • 4 fan levels (34-54 DB)
  • Able to remove Covid bacteria 


  • Not fit for larger rooms
  • No handles if you want to move it around

Best for 400 sq ft Room: Okaysou Apollo 718 

Okaysou Apollo 718 Air Purifier for Home Large Room

This model purifies a room of 300 sq ft in 15 minutes, 800 sq. ft in one hour.

The Apollo 718 is only about 5 pounds, making it easy to move from room to room as needed, but it packs quite a punch in cleaning and filtering your air. It features a four-stage purification process that uses HEPA and carbon filters to trap 99 percent of airborne particles as small as 0.3 microns.

Reviewers have praised the 718’s advanced filter system that uses HEPA technology to filter out even the tiniest particles from the air. They’ve also loved how quiet this machine is when it runs and how energy efficient it is compared to other products on the market.


  • Ultra Quiet 23Db
  • Convenient Control Panel
  • 3 Stage Filtration System
  • Wheel Night Light
  • Washable Pre-filter
  • H13 True HEPA Filter


  • Doesn’t have a fan speed control
  • filter needs to be replaced after every 6 month

Best for 600 sq ft Room: Alen BreatheSmart FLEX

Alen BreatheSmart FLEX True HEPA Air Purifier

Purifies and cleans up to 600- 700 sqft every 30 minutes. 

The FLEX is designed for medium rooms up to 600 square feet, making it the perfect fit for bedrooms or small spaces where you need a lot of air cleaning power in a small package. In addition to its ability to clean the air, this model also features an ion generator that can help reduce static electricity and microbial growth on surfaces in your room.

The Alen BreatheSmart FLEX has been designed to work with any HVAC system. The unit can be installed on the wall or ceiling or even placed on the floor if you prefer.


  • Sleek design, classy and stylish look
  • Complimentary H13-grade HEPA filter
  • Customized filter options for different needs
  • Multiple front panel customization options
  • 100% ozone-free, timer, and child lock feature
  • Energy-efficient, Energy Star certified
  • Lifetime warranty


Best for 800 sq ft Room: Okaysou Airmax 8L

Okaysou AirMax8L Air Purifier Review

Circulates air up to 1.5x per hour in a room size of 800 sq. ft / 3x per hour in 500 sq. ft.

The Okaysou Airmax 8L is designed to be as energy-efficient as possible while providing high-performance results. It uses a current motor with a brushless design that’s both quieter and longer-lasting than standard AC motors. It also features an auto-off timer set to turn off after 1, 2, 4, or 8 hours of use.

Fan speeds are adjusted automatically based on how much pollution is in the air, and it’s got an ultra-quiet sleep mode that helps you get restful sleep at night. You can control it using the remote or through Alexa.


  • H13 grade true HEPA filter for particle removal
  • Honeycomb structured carbon filter for odors
  • Large filter surface area
  • 5 stage filtration, moderate CADR ratings
  • Sleek design, touch control panel
  • Child-lock, sleep mode, timers
  • 5-years warranty cover, 100% ozone-free, CARB compliant


  • No air quality sensor
  • No separate filter replacement indicator

Best for 1000 sq ft Room: AirDoctor 5000

AirDoctor 5000 Air Purifier review

Circulates the air in 1,001 sq. ft. 4x/hour or 2,001 sq. ft. 2x/hour.

This model is set apart from other air purifiers: its filtration ability and durability. The first thing you’ll notice about it is its size—at just over two feet tall, it looks like a large lampshade rather than an air purifier. It makes it ideal for smaller spaces where you don’t want something to stick out like a sore thumb.

The AirDoctor 5000 is also one of the quietest air purifiers on the market, emitting just 28 dB at its lowest setting. This means it’s slower than a whisper, so you can sleep peacefully or enjoy a movie without disruption from your air purifier.


  • State of the Art Ultra HEPA
  • Dual Action Carbon/VOC Filter
  • 100% Sealed System
  • Auto mode
  • Change Filter Alert
  • Quiet Performance


  • Replacement filters are costly

People Also Ask

Does the size of the air purifier matter?

The answer is a resounding yes—you want to get the right size for your needs.

The size of an air purifier refers to its ability to clean the air in terms of square footage. It’s also known for its ‘cleaning capacity.’ An air purifier that isn’t designed for your space will not be able to clean the air sufficiently and, therefore, won’t be very effective in removing contaminants.

How do I calculate air purifier coverage?

Calculating the coverage of an air purifier is pretty straightforward, but it’s essential to know that there are ways you can calculate the range.

Step 1. You’ll need to have some information about your room, like its size and shape. If it’s rectangular or square, measure the length and width and multiply them to find the area in square feet.

Length x Width = Square Footage

For example: 50’ x 20’ = 1,000 sq ft.

Step 2. Once you’ve got that number, look at your air purifier’s box or manual to determine its CADR rating—the best way to find an air purifier that will work for your space. For example, the higher the CADR number, the faster it’ll be able to clean a room of a specific size.

You need to multiply your square footage by 2, dividing it by the CADR rating on the machine you’re considering buying. So if your living space is 1,000 square feet and the CADR rating on an air purifier you’re considering is 300, you’d do this:

For example:  1000 x 2 = 2000

            2000 / 300 = 6.67

            Therefore, that air purifier would cover about 667 square feet in your home.

Do air purifiers work in large rooms?

Air purifiers can work in large rooms, but they don’t have to be the exact model you would use in a smaller space. Of course, a larger room will require a more powerful air purifier than a small one, so you should pay attention to the strength of its CFM (cubic feet per minute) number. 

It’s also important to note that most air purifiers are designed to clean a specific size of the room—and if the space is more significant than that, the air won’t circulate efficiently enough to get wholly cleansed. So you’ll want something with a more extensive range if you’re looking for an air purifier for a large room.

Does ceiling height affect air purifiers?

Yes, the height of your room’s ceiling will affect the performance of your air purifier.

The height of your room’s ceiling affects its volume, which means there is more space for airborne particles to circulate. Unfortunately, if you have a high ceiling, your air purifier has to work harder to get rid of all those particles—which means it will use up more power and eventually need to be replaced.

For example, The room is 100 sq ft.

           Ceilings are 8 ft high

          10 sq ft. x 8 ft = 800 Cubic feet


Overall, the size of your air purifier is going to matter. The more surface area it has to pump clean air out, the more space you cover. Purchase an air purifier that’s too small, and you won’t be able to cleanse a large room effectively. 

There isn’t a general rule that can be applied across the board here—if you’re only dealing with a small room, then most retailers will suggest a small air purifier. But if you’ve got a larger space to take care of, it pays to go for something bigger. Thanks for reading!

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