The higher the
Greater or Smaller? That being stated, it is in every case better to choose an air purifier that has a marginally bigger area rating that your room region. That is, it is smarter to have an air purifier that is somewhat greater than one that is excessively little for your necessities.
Generally, you want a CADR that's at least two-thirds the square footage of the room you intend to purify. For instance, a 200 sq. ft. room would benefit from an air purifier with a CADR of 133 (200 x 2/3 = 133).
Air circulation: If your room has poor air circulation, or is a complex shape (such as an L shape or a long thin shape) then you may benefit from multiple smaller air purifiers to improve ventilation. Two air purifiers placed at different locations in your room may help improve air circulation.
A purifier that's too small may struggle to adequately clean the air in larger spaces, while one that's too powerful for a small room could be unnecessarily loud and consume more energy than needed.
In theory, you would get the best results by having an air purifier in every room of your home. However, the cost of doing this can make it impossible for most people. If you're wondering whether you need an air purifier for each room, start with an affordable two: one for your bedroom and one for the living area.
Placing an air purifier in your bedroom can allow you to breathe clean air for hours at a time, which you may not be able to experience during the day. However, to get the most benefit to your indoor air quality, you should make sure that your air purifier is in an ideal spot, like your nightstand, while you sleep.
The higher the MERV rating, the better the air filter is at removing particles. Cheap air filters typically have a low MERV rating of 6 or less, while expensive air filters can have a MERV rating of up to 13. This means that they can remove much smaller particles, like bacteria, viruses, and mold spores, from the air.
Do not forget about the height of the position of the purifier. Specialists recommend placing the device on the floor, because it is near the ground that there is a higher concentration of pollutants. Setting it on a shelf can significantly reduce the filtration efficiency.
The most commonly asked question is how long does it take for an air purifier to work? Generally, an air purifier takes about 30 minutes to two hours to purify a room. But there are aspects including the size of the room, filter, speed of purification, and more that must be factored in.
It is important to select a room air cleaner specific for your room size. A general rule to consider is the “2/3 rule” – find an air cleaner with a CADR that is at least 2/3 the square footage of the space.
Choose a Central Location
Place your air purifier in a central area of the room to allow for efficient airflow and circulation. This means you should keep your device away from walls, corners, and other obstructions (more on why in a second).
The global residential air purifier market size was valued at USD 12.15 billion in 2024 and is projected to reach from USD 13.07 billion in 2025 to USD 23.41 billion by 2033, growing at a CAGR of 7.56% during the forecast period (2025-2033).
An air purifier cannot filter allergens, viruses, and unpleasant odors if it is not sized correctly for the space.
Most air purifiers consume between 30 and 250 watts of electricity, with the average unit using around 50 watts. To put this into perspective, a typical 60-watt incandescent light bulb uses more energy than many air purifiers.
Many people think that switching it off during the night or when they're not present is a logical energy-saving measure, but it is recommended to keep it running constantly. Once you turn off your air purifier, the air quickly becomes contaminated again with mold, dust, dander, and other pollutants present in the air.
While air purifiers are effective at removing the majority of the offending allergens from a single room, they do not take away all the airborne particles, Dr. Alana Biggers-Walker, associate professor of medicine at the University of Illinois Chicago, told Live Science.
What are the downsides of air purifiers? There aren't a lot of downsides to having an air purifier in your home aside from the financial investment. Many ionizers, especially older models, can generate ozone when they are operating, which is known to exacerbate asthma.
the price of the air purifier
If it's extremely expensive, it may be outside your budget but more importantly, it needs to offer quite a bit for it to be a good value. Top rated units fall in the $120 to $200 range.
The best air purifier for large rooms we've tested at a budget price point is the Winix 5500-2. This air purifier can't quite compete with higher-end models like the Honeywell HPA300 or the NuWave OxyPure for raw clean air delivery rate, so it won't clear particulates from the air quite as quickly in bigger spaces.
Well, the answer isn't as easy. In a typical home, an effective air purifier starts to deliver clean air within 30 to 60 minutes. But this time changes, depending on several factors such as your room size, the indoor air quality and even the placement of the device.
Is It Safe to Leave an Air Purifier On While You're Away? Leaving an air purifier on while you're away from home is generally considered safe, as most modern air purifiers are designed for continuous operation.
Keep Your Air Purifier Away from Heat
Air purifiers work hard and can get hot after a period of use. To prevent overheating and potentially damaging your device, keep it away from vents or radiators. Avoid running your unit for sustained periods while it is in direct sunlight.