How to pick the right air purifier for your room: From CADR to room size, here's a simple guide to getting cleaner air at home

Choosing the right air purifier can be tricky. One of the major aspects while buying an air purifier is to match the purifier’s capacity to your room size . If the device is too small, it won’t clean the air effectively. Remember that an air purifier can do its job well only if it matches your room size. This may feel overwhelming, but is an important point to consider if you are buying an air purifier. Here’s how you can identify the perfect one for your space.


Measure the room first
Start by measuring the length and width of your room. Multiply these numbers to get the area in square feet. For example, a 12×10 ft room equals 120 sq ft. If your ceiling is higher than 8 ft, you’ll need a more powerful purifier.

If your ceiling is over 8 ft, or you’re using the purifier in a big hall or open-plan area, you’ll need one with higher CADR . Most purifiers are rated for standard rooms, so upgrading the capacity helps maintain performance.


Understand what CADR means

The Clean Air Delivery Rate (CADR) tells you how quickly a purifier can clean the air. A higher CADR means faster and more efficient filtration. Always look for models that clearly mention CADR for smoke, dust, and pollen.


Follow the 2/3 rule
Experts suggest the “two-thirds rule” when buying an right purifier. The smoke CADR should be at least two-thirds of your room’s area. So, for a 120 sq ft room, look for a smoke CADR of around 80. This ensures that the air purifier is capable of handling the space efficiently or not.


Check Air Changes Per Hour (ACH)

Air Changes per Hour (ACH) shows how many times the purifier filters all the air in a room in one hour. For homes in polluted areas or for people with allergies, choose one with 4-5 air changes per hour for cleaner and healthier air.


Consider placement
Where you keep your air purifier matters. Place it away from walls and furniture, and keep some space around it for better airflow. Close doors and windows while it’s running so it can clean indoor air effectively.


One large unit or two smaller ones?
If your space is too big or open, a single purifier may not be enough. You can either go for a high-capacity model or use two smaller units in different corners for better coverage.

Once you’ve matched the purifier to your room size, look at other features — such as filter type ( HEPA and activated carbon), energy efficiency, and noise level.