What is CADR? An Important Metric You Need to Know Before Buying an Air Purifier

CADR shows the speed at which an air purifier can clean your room’s air. It represents the volume of filtered air the system delivers over a specific period. This was developed by the Association of Home Appliance Manufacturers (AHAM) in the early 1980s to standardise the performance of air purifiers across all types and categories.¹  In this article, we explain what CADR is and how it can help in choosing an air purifier for your needs.

How CADR is Measured 
 

According to AHAM, the CADR rating for air purifiers signals the effectiveness of removing different particle sizes. During the test, the air purifier run on the highest fan speed. Each particle is measured and given its own CADR rating. Each air purification system lists these CADR values:

• Dust: For visible particles such as dirt and lint.
• Pollens: For allergens.
• Smoke: For fine particles in the air from cooking, traffic, or burning.
• PM 2.5: PM 2.5 CADR is a measurement of the particles that are smaller than 2.5 microns.
   

In the US, the CADR is measured in CFM (cubic feet per minute). In Asia, it is measured in cubic meters per hour (m3/h), 0.59 cu ft/min is equivalent to one cubic metre per hour, or 1 CFM = 1.69 m3/h.²

How to Match CADR to Your Room Size

Matching the right CADR starts with your room’s size and how quickly the air needs to be cleaned. Use the steps below to choose the best air purifier for your space.

• Step 1: Measure your room
   

  Multiply length × width × height to get the room volume.
   

• Step 2: Know the ideal air changes
   

  Most homes need 4 to 5 air changes per hour (ACH) for effective purification.
   

• Step 3: Match room size with CADR
   

  Select a purifier with a CADR sufficient to filter your room’s air volume according to the recommended air changes per hour (ACH).
   

• Step 4: Adjust by room type
   

  Bedrooms need a lower CADR than living rooms or open areas with more people.
   

• Step 5: Avoid under- and over-sizing
   

  Low CADR cleans too slowly. Very high CADR may increase noise and power use. Slightly higher-than-minimum CADR works better for Indian pollution conditions.
   

For medium-sized rooms up to 310 sq. ft., the Forbes 230 Surround 360° Air Purifier is a suitable choice. It uses Surround 360° Air Intake Technology and a 4-stage filtration system with a True HEPA H13 filter to remove 99.97% of fine particles, dust, and allergens. The activated carbon layer also helps reduce odours and VOCs. With a long filter life of up to 1.5–2 years, quiet sleep mode, and timer settings, it delivers reliable indoor air cleaning with low upkeep, making it a practical choice for bedrooms, studies, or compact living areas.
 

Misconceptions About CADR

Consumers often misinterpret what CADR really means. Here are the most prevalent misconceptions:
 

• Higher CADR means better filtration.
   

  CADR specifically measures how fast air is cleaned, not how thoroughly pollutants are removed. Filter quality and sealing still matter.
   

• Room size labels are reliable benchmarks.
   

  Room size claims differ by brand and testing method. CADR provides a consistent metric for comparison. 
   

• Larger units are always superior.
   

  Physical size or wattage does not guarantee higher airflow efficiency or purification speed. 
   

• One CADR rating is sufficient.
   

  Separate CADR ratings exist for dust, pollen, and smoke. It’s important to assess the different scores when choosing an air purifier for your home.

Key Factors to Consider When Choosing an Air Purifier
 

CADR should not be the sole criterion for choosing an air purifier. Here are the key factors to consider:
 

• Filter Type: True HEPA filters capture fine particles like dust, pollen, and microbes. Activated carbon filters help remove odours, smoke, and VOCs.
   
• Room Size Coverage: Ensure the purifier can handle the square footage of your room for consistent purification.
   
• Noise Levels: Review the decibel rating to ensure the purifier operates quietly, particularly in bedrooms or study spaces.
   
• Power Consumption: Consider energy efficiency for long-term use.
   
• Maintenance & Filter Life: Check how frequently the filters require replacement and consider the associated costs.
   
• Price: Compare models based on air purifier price to balance performance, features, and budget without compromising quality.
   
• Additional Features: Timer settings, sleep mode, and air quality indicators can enhance convenience and usability.
   

These factors help you pick a purifier that suits your space, lifestyle, and indoor air quality needs. Suitable for medium to large rooms measuring up to 480 sq. ft., the Forbes Smart 355 Surround 360° Air Purifier offers effective 4-stage purification with a True HEPA Grade 13 filter and Surround 360° Air Intake Technology. Its smart app control, auto and sleep modes, and real-time PM2.5 monitoring make it convenient, efficient, and easy to maintain.
 

Conclusion
 

Being aware of CADR helps you select the most suitable air purifier for your home or workplace. By considering room size, filter type, noise levels, maintenance, and overall efficiency, you can make a practical decision. Keeping these factors in mind will help you buy air purifier that delivers cleaner, healthier indoor air with reliable performance.
 

Sources: 

1. https://www.aham.org/AHAM/Standard_Chart_Page.aspx
2. https://ahamverifide.org/ahams-air-filtrations-standards%e2%80%a8/https://ahamverifide.org//wp-content/uploads/2021/11/White-Paper-Portable-Air-Cleaners-and-AIr-Changes-per-Hour-FINAL-00106301.pdfhttps://www.epa.gov/pm-pollution/particulate-matter-pm-basics#:~:text=PM10%20:%20inhalable%20particles%2C%20with,than%20the%20largest%20fine%20particle.