Tips given by Hunter Fan, I thought this was really helpful as a resource.

1. Measure the room where the air purifier will be used.

2. Click on the room size that most closely matches your room on the Air Purifier Selcection Guide.

3. Select the Hunter model with the CADR (Clean Air Delivery Rate)* performance rating to fit your room.

Things To Consider Before Buying An Air Purifier
How do you know that an air purifier is truly effective? Check the Association of Home Appliance Manufacturers (AHAM) seal on the package. AHAM independently tests and certifies air purifier performance. All reputable air purifier manufacturers display the AHAM certification seal, which includes the unit’s Clean Air Delivery Rate (CADR). CADR is the industry standard rating system for an air purifier’s effectiveness.

CADR: Real World Performance
CADR measures the amount of clean air that a purifier delivers into a room. It gauges real world performance, taking into account filter efficiency, airflow and room size. CADR is the single most important piece of information you need to make a head-to-head comparison of air cleaner performance.

What’s Changing?
Air Changes per Hour (ACH) is simply a measurement of how much air a unit moves, not how effectively the air is cleaned. Likewise, a filter’s “efficiency” measures the amount of particles that the filter material alone can capture in lab tests. These tests don’t incorporate real world factors like airflow design or fan speed. Remember, real world air purifier effectiveness is measured by CADR—not ACH or filter efficiency tests!

*CADR (Clean Air Delivery Rate) is an independently tested and certified measure of how effective an air purifier performs in the real world.