Improving indoor air quality has become a top priority for many, especially as we spend more time indoors. Room air purifiers are an effective solution for tackling common pollutants like dust, pet dander, allergens, smoke, and other airborne particles. One of the most important factors to consider when purchasing best room air purifier is its clean air delivery rate (CADR), which ensures that the device is suitable for the size of your room. In this article, we’ll take a closer look at how air purifiers work, the significance of CADR, and highlight our top pick for 2025.
What is CADR (Clean Air Delivery Rate)?
The clean air delivery rate (CADR) is a key metric used to measure the effectiveness of an air purifier. It refers to the volume of air (in cubic feet per minute, or CFM) that the air purifier can filter, removing airborne pollutants like dust, pollen, and smoke. A higher CADR number means the purifier is more efficient at filtering out contaminants from the air, making it suitable for larger rooms.
The CADR is usually measured for three types of pollutants:
• Dust: Particles that are small and light enough to float in the air.
• Pollen: Common allergens that can trigger asthma or seasonal allergies.
• Smoke: The fine particles and chemicals found in tobacco smoke and wildfire smoke.
For a room air purifier to be effective, you need to match the CADR with the size of your room. The larger the room, the higher the CADR you’ll need to ensure the purifier can clean the air efficiently.
How CADR Relates to Room Size
To determine the ideal air purifier for your space, it’s important to consider both the CADR and the square footage of the room. Here’s a general rule of thumb to follow:
| Room Size | Recommended CADR |
| Small Room (Up to 200 sq. ft.) | CADR: 100-150 CFM |
| Medium Room (200-400 sq. ft.) | CADR: 150-250 CFM |
| Large Room (400-600 sq. ft.) | CADR: 250-350 CFM |
| Extra-Large Room (600-1,000 sq. ft.) | CADR: 350+ CFM |
How Do Room Air Purifiers Work?
The best room purifiers are equipped with various filtration systems that trap particles from the air. The most common and effective type of filter is the high-efficiency particulate air (HEPA) filter. HEPA filters can capture particles as small as 0.3 microns with 99.97% efficiency, making them ideal for removing airborne allergens, dust, and other fine particles.
Here’s a breakdown of how a typical air purifier works:
1. Intake: Air is drawn into the purifier through vents.
2. Filtration: The air passes through the HEPA filter (and sometimes additional filters like activated carbon or UV filters) to trap contaminants.
3. Clean Air Release: The purified air is then released back into the room, improving overall air quality.
Our Top Pick for the Best Room Air Purifier: AirDoctor Air Purifiers
AirDoctor is the best room air purifier known for its advanced filtration system, featuring a powerful HEPA filter that captures 100% of airborne particles, including allergens, dust, and pet dander. Its carbon filter also helps eliminate odors and volatile organic compounds (VOCs), making it a great choice for improving air quality in medium to large rooms.
The three AirDoctor models have been independently tested by Intertek laboratories for CADR. Assessing the smallest, most dangerous particle, their smoke CADR ratings are as follows:
• The CADR for AirDoctor 1000 is: 152
• The CADR for AirDoctor 2000 is: 162
• The CADR for AirDoctor 3000 is: 336
• The CADR for AirDoctor 5000 is: 556
Conclusion
Choosing the best room purifiers is all about understanding how the CADR relates to your room size. By ensuring the CADR is sufficient for your space, you’ll get the best performance out of your air purifier. Keep in mind that a higher CADR is better for larger rooms, while a moderate CADR works well for smaller spaces.
