When shopping for an air purifier, you’ll likely encounter the term “CADR” prominently displayed on packaging and in specifications. CADR, which stands for Clean Air Delivery Rate, is a standardized measurement that indicates how effectively an air purifier filters specific airborne particles. Developed by the Association of Home Appliance Manufacturers (AHAM), this rating helps consumers compare different air purifier models objectively. CADR measures performance against three common pollutants: tobacco smoke, dust, and pollen, with higher numbers indicating greater cleaning efficiency. Understanding CADR ratings is essential for selecting an appropriately sized air purifier that will effectively clean the air in your space.
CADR is an industry-standard metric that quantifies an air purifier’s cleaning efficiency by measuring the volume of filtered air delivered by the device. Specifically, it indicates the cubic feet per minute (CFM) of air that has been cleared of specific particles. The CADR rating was established by AHAM in the 1980s to provide consumers with a reliable way to compare different air purifier models.
Three separate CADR ratings are typically provided for each air purifier, corresponding to three different pollutants: tobacco smoke (particles 0.1-0.3 microns), dust (particles 0.5-3 microns), and pollen (particles 5-11 microns). These pollutants represent a range of particle sizes commonly found in household air.
The higher the CADR number, the faster and more efficiently the air purifier removes these particles from the air. For example, an air purifier with a dust CADR of 200 will reduce dust particles twice as quickly as a model with a dust CADR of 100.
How CADR Is Measured
CADR testing follows a standardized protocol conducted in a controlled chamber of approximately 1,008 cubic feet (equivalent to a 12′ x 12′ room with 7′ ceilings). During testing, specific contaminants are introduced into the chamber, and sensors measure how quickly the air purifier reduces their concentration.
The testing procedure accounts for both the air purifier’s filtration efficiency and its airflow rate. This is important because an air purifier with exceptional filtration but poor airflow might perform worse overall than one with moderate filtration and excellent airflow.
CADR values are typically expressed in cubic feet per minute (CFM) in the United States. In other countries, you may see measurements in cubic meters per hour (m³/h). For conversion, 1 CFM equals approximately 1.7 m³/h.
| Pollutant | Particle Size Range | Typical CADR Range |
|---|---|---|
| Tobacco Smoke | 0.1-0.3 microns | 10-450 CFM |
| Dust | 0.5-3 microns | 10-450 CFM |
| Pollen | 5-11 microns | 25-450 CFM |
Understanding CADR Numbers
CADR ratings typically range from 10 to 450, with higher numbers indicating better performance. For residential use, air purifiers commonly have CADR ratings between 100 and 300. Commercial or large-space air purifiers may exceed these values.
The minimum recommended CADR for an air purifier depends on your room size. AHAM suggests that the CADR (for tobacco smoke) should be at least two-thirds of the room’s area in square feet. For example, a 300 square foot room would require an air purifier with a minimum smoke CADR of 200.
Different pollutants typically have different CADR values for the same air purifier. Usually, the pollen CADR is highest because larger particles are easier to filter, while the smoke CADR is lowest since smaller particles are more challenging to capture.
| CADR Rating | Performance Level | Recommended For |
|---|---|---|
| 10-100 | Low | Small rooms (<150 sq ft) |
| 101-200 | Medium | Medium rooms (151-300 sq ft) |
| 201-300 | High | Large rooms (301-450 sq ft) |
| 301-450 | Very High | Very large rooms/open spaces (450+ sq ft) |
CADR vs. Room Size
Matching your air purifier’s CADR to your room size is crucial for effective air cleaning. The 2/3 rule (CADR should be at least two-thirds of room area) provides a simple guideline, but other factors like ceiling height and air pollution levels should also be considered.
For rooms with high ceilings (above 8 feet), increase the recommended CADR proportionally. For instance, if your ceiling is 10 feet (25% higher than standard), increase your target CADR by 25%.
For spaces with increased pollution sources (like pet dander, cooking fumes, or multiple occupants), opt for a CADR rating higher than the minimum recommendation to ensure adequate air cleaning.
| Room Size (sq ft) | Minimum Recommended CADR | Optimal CADR for Sensitive Individuals |
|---|---|---|
| 100 | 67 | 100+ |
| 200 | 133 | 200+ |
| 300 | 200 | 300+ |
| 400 | 267 | 350+ |
| 500 | 333 | 400+ |
Limitations of CADR Ratings
While CADR provides valuable information, it has several limitations consumers should be aware of. First, CADR tests are conducted in controlled environments that don’t perfectly simulate real-world conditions. Actual performance can vary depending on the layout of your space, furniture placement, and air circulation patterns.
Second, CADR doesn’t measure an air purifier’s effectiveness against gases, odors, or VOCs (volatile organic compounds). For these pollutants, you’ll need to look for air purifiers with activated carbon or other specialized filtration media.
Third, CADR testing runs air purifiers at their highest speed setting, which is typically the loudest. Many users operate their air purifiers at lower, quieter settings, which will reduce the effective CADR.
Finally, CADR doesn’t account for long-term performance. As filters clog with particulates over time, the CADR will decrease until filters are replaced. Regular maintenance is essential to maintain the rated performance.
What CADR Doesn’t Tell You
- Energy efficiency
- Noise levels at different speeds
- Filter lifespan
- Effectiveness against gases and odors
- Long-term maintenance costs
- Smart features and connectivity options
CADR Ratings for Different Pollutants
The three standard CADR measurements (smoke, dust, and pollen) represent particles of different sizes. Understanding these distinctions helps you choose an air purifier that addresses your specific air quality concerns.
The smoke CADR measures effectiveness against the smallest particles (0.1-0.3 microns). This rating is particularly important for households with smokers, near wildfire zones, or in areas with high combustion pollutants. It’s also relevant for those concerned about viruses, which often fall within this size range.
The dust CADR measures effectiveness against medium-sized particles (0.5-3 microns). This includes household dust, pet dander, and many bacteria. This rating is crucial for allergy sufferers and those in dusty environments.
The pollen CADR measures effectiveness against larger particles (5-11 microns). This is especially important for seasonal allergy sufferers or those in areas with high pollen counts. Most air purifiers perform best against these larger particles.
Which CADR Matters Most for Different Needs
| Primary Concern | Most Important CADR |
|---|---|
| Allergies (seasonal) | Pollen |
| Allergies (year-round) | Dust |
| Asthma | Dust and Smoke |
| Tobacco smoke exposure | Smoke |
| Respiratory protection | Smoke |
| Pet dander allergies | Dust |
Popular Air Purifiers and Their CADR Ratings
The market offers numerous air purifier models with varying CADR ratings and price points. This comparison can help you find the right balance between performance and cost. Note that higher-priced models don’t always have better CADR ratings – sometimes you’re paying for additional features like smart connectivity, design, or brand premium.
| Air Purifier Model | Smoke CADR | Dust CADR | Pollen CADR | Room Size (sq ft) | Approximate Price Range |
|---|---|---|---|---|---|
| Coway AP-1512HH | 233 | 246 | 240 | 361 | $200-$250 |
| Winix 5500-2 | 232 | 243 | 246 | 360 | $150-$200 |
| Honeywell HPA300 | 300 | 320 | 300 | 465 | $200-$300 |
| Blueair Blue Pure 211+ | 350 | 350 | 350 | 540 | $300-$350 |
| Levoit Core 300 | 141 | 140 | 145 | 219 | $100-$150 |
| Dyson Pure Cool TP04 | 164 | 177 | 183 | 266 | $500-$650 |
Alternative Air Purifier Metrics
While CADR is an important performance indicator, several other metrics provide additional insight into an air purifier’s capabilities. Understanding these metrics gives you a more comprehensive picture of performance.
ACH (Air Changes per Hour) indicates how many times an air purifier can filter all the air in a room within an hour. For example, an ACH of 5 means the device filters all the room’s air five times every hour. For people with allergies or respiratory conditions, an ACH of 4-5 is recommended.
Filter type and efficiency are crucial considerations. HEPA (High-Efficiency Particulate Air) filters must remove at least 99.97% of particles 0.3 microns in diameter. True HEPA filters offer superior filtration for the smallest particles compared to “HEPA-type” or “HEPA-like” filters.
Noise levels are measured in decibels (dB) across different fan speeds. This is important for bedroom use or other quiet spaces. Most air purifiers range from 20-60 dB depending on the speed setting.
Energy consumption, often measured in watts, affects operating costs. ENERGY STAR certified air purifiers are at least 40% more energy-efficient than standard models. Some air purifiers list annual energy consumption to help estimate running costs.
How to Use CADR in Your Purchasing Decision
To effectively use CADR ratings when purchasing an air purifier, follow these steps:
- Measure your room size in square feet (length × width). For open floor plans, consider the entire space that needs purification.
- Identify your primary air quality concerns (allergies, smoke, dust, etc.) to determine which CADR measurement is most important for your needs.
- Calculate the minimum recommended CADR using the 2/3 rule: room area (sq ft) × 2/3 = minimum smoke CADR.
- Adjust for ceiling height if your ceilings are higher than 8 feet.
- Consider additional factors like noise, energy efficiency, filter replacement costs, and special features.
For spaces with multiple pollution sources or for individuals with respiratory sensitivities, consider choosing an air purifier with a CADR rating 20-30% higher than the minimum recommendation. This provides extra cleaning capacity for challenging conditions.
Remember that CADR ratings are measured at maximum fan speed. If you plan to use your air purifier primarily at lower speeds for noise reasons, you might need a model with a higher rated CADR to compensate for the reduced performance at lower settings.
Balancing CADR with Other Factors
While CADR is important, balance it with other considerations:
- Filtration technology: HEPA, activated carbon, ionization, UV-C, etc.
- Noise level: Especially important for bedroom use
- Energy efficiency: Affects long-term operating costs
- Filter replacement cost and availability: Ongoing maintenance expenses
- Smart features: Air quality sensors, auto mode, app control
- Size and aesthetics: How the purifier fits into your space
- Warranty and reliability: Product longevity and manufacturer support
The optimal air purifier combines appropriate CADR ratings with the features that matter most for your specific situation and budget. For most consumers, prioritizing adequate CADR for your space and focusing on True HEPA filtration provides the best foundation for clean air, with other features as secondary considerations.