Air Purifier CADR: Easy Formula, Killer Tips & Top FAQs
CADR is the most popular Jargon in air purifiers.
So what exactly air purifier CARD is?
Answer: Air purifier CADR (clean air delivery rate) meaning is the measurement on how much airflow an air purifier can filter. It indicates the volume of filtered air an air purifier delivers.
Air purifier CADR ratings are extremely important since it determines the efficiency of air purifiers to some extent. It specifies how quickly an air cleaner is able to remove contaminants, dust, pollens, smoke in a room.
Thus, it is vital to understand CADR rating - #1 specification in air purifiers so that you can pick the ideal one for your clean air needs.
Table of Contents:
#1. Air Purifier CADR Factors & Formula
#2. Best Guide to Choose the Best CADR
#3. Top FAQs on Air Purifier CADR Rating
#1. CADR for Air Purifier: Easiest Calculation Formula
Before stepping into the formula, knowing the factors (the variables) that determine the CADR rating for air purifies.
Top 3 Factors Determine Air Purifier CADR
Room area (unit: square footage) – This factor is the length and width of your room, which is the flat area of your room.
Ceiling height (unit: in foot) – The height from your room's ceiling to the ground.
Air changes per hour (abbreviated as ACH, unit: hour) – It is your desired air changes per hour. It is advised to choose a 2 ACH for regular air cleaning.
How to Calculate Air Purifier CADR Ratings
Formula for CADR in cubic feet/minute: [(ACH X Room Area X Ceiling Height)/60 cfm
Formula for CADR in cubic meter/hour: [(ACH X Room Area X Ceiling Height)/60] X 1.699 m3/h
Let's calculate the CADR rating with via the formula above.
For example, your room area is 15 (L) ft X 15 (W) ft = 225 ft2 and the ceiling height is 10 ft. The desired air change per hour is 2 hours. Put these numbers into the formula:
CADR in cubic feet/minute = [(2 X 225 X 10)/60 = 75 cfm
CADR in cubic meter/hour = [(2 X 225 X 10)/60)] X 1.699 = 127 m3/h
The calculation result means that this room needs an air purifier with at least 75 cfm or 127 m3/h to meet your desired air changes per hour (2 hours) in this calculation.
Thus, when you select a HEPA air purifier for your room, focus on if the CARD rating of the air purifier meets your room's needs based on the calculation.
This formula is applied to all air purifier CARD rating calculation, including Levoit, Blue Air, Xiaomi, Winix, Shark, Philips, IKEA, Samsung, Bionaire, Breville, Coway, Daikin, Honeywell, AZEUS, Homedics, TruSens, Holmes, Westinghouse, Medify, Dyson, Vornado, etc.
For example, when you see an air purifier with 100, 150, 240, 280, 300, 350, 400, 500, 800, 1,000 cfm, it means that this air purifier can deliver 100, 150, 240, 280, 300, 350, 400, 500, 800, 1,000 cubic feet of air in every minute on its highest fan speed settings.
#2. Best Guide to Choose the Best CADR
What is a good CARD rating for air purifiers? How to choose the ideal CARD of air purifiers?
The golden rule is: Choose the right air purifier CADR rating based on your room area and your specific requirements.
If your room is 200 ft2 and 10 ft heigh and you need 1-hour ACH, you should buy an air purifier with a minimum 33 cfm (56 m3/h) CADR rating. If your room is 200 ft2 and 10 ft heigh and you need 0.5-hour ACH, you should buy an air purifier with a minimum 17 cfm (28 m3/h) CADR rating.
Take Purivortex 201B Pro and V1 as the typical examples. 201B Pro has 47 m3/h (28 cfm) CADR at its lowest fan speed. The number means that it can at least clean air around 47 m3 room area per hour.
V1 has 120 m3/h (70 cfm) CADR at its lowest fan speed, which means that it can clean air at least 120 m3 room area per hour.
Just get the ideal air purifier for your bedroom, kitchen, living room, master room, nursery room, workout room based on different room area and your specific air changes per hour.
#3. Top FAQs on Air Purifier CADR Rating
You may have some questions in terms of air cleaner CADR. Thus, we have included frequently asked questions so that you can have further insights on CADR and make a smart shopping decision.
1. What is a Good CADR Rating for Air Purifiers
A good CADR rating of an air purifier is able to cover your room based on your needs of air changes per hour. For example, if your room area is 150 ft2 with 10 ft ceiling height and 1 hour ACH, a good CADR of air purifiers would be 25 cfm or 42 m3/h.
2. Is a Higher CADR Rating Better
In most cases, higher CADR rating is better since the higher the CADR, the better the air purifier's overall ability to clean indoor air.
However, if you just wanna get an air purifier for a small room, like 100 ft2, it is not necessary to buy an air purifier with super high CADR like 1,000 cfm. A small air purifier is enough to cover your small space.
In such a circumstance, opting to a high-CADR air purifier will increase the costs of operation and filter replacement costs.
Thus, higher CADR rating doesn't always mean better. It is determined by your specific room area.