CADR Calculator: Find the Right Air Purifier for Your Room Size

We offer two types of calculators to determine the required CADR for your room’s air purifier:

1. CADR Calculator (general use)
2. Tobacco Smoke CADR Calculator using AHAM’s 2/3 Rule

CADR Calculator (general use):

To calculate the required CADR, you need three key measurements:

1. Room Area – Measure the length and width of the room (in square feet) using L × W.
2. Ceiling Height – Determine the height of the room.
3. Desired Air Changes per Hour (ACH) – For general use, at least 3 ACH is recommended.

Use the calculator below to find the required CADR.

What is CADR?

CADR (Clean Air Delivery Rate) measures an air purifier’s efficiency in filtering airborne particles. It indicates how much clean air the purifier delivers per minute and is expressed in CFM (cubic feet per minute) or m³/h (cubic meters per hour).

For example, an air purifier with a CADR of 200 CFM means it produces 200 cubic feet of filtered air per minute at its highest fan speed.

It’s important to note that “clean” refers to filtered air, not filtration quality. CADR measures airflow efficiency but doesn’t account for filter effectiveness. Filtration quality depends on factors like filter type and grade. For instance, a True HEPA filter captures 99.97% of particles as small as 0.3 microns.

How Important is the CADR?

The CADR rating is the primary metric for assessing an air purifier’s efficiency. However, overall performance also depends on factors like filter type, filter surface area, and air intake/outlet design.

In a nutshell:

• Air Purifier Efficiency = CADR rating (how fast air is cleaned)
• Air Purifier Effectiveness = Filter type (how well pollutants are removed)

Tobacco Smoke CADR Calculator using AHAM’s 2/3 Rule:

You can easily calculate the required Tobacco Smoke CADR using AHAM’s Formula) with the following:

1. Room area (in square feet or L × W)
2. Ceiling height, which is set at a constant 8 feet

AHAM’s CADRs Certificate Sample:

AHAM’s CADR

AHAM (Association of Home Appliance Manufacturers) certifies air purifiers with three CADR ratings: Tobacco Smoke (for ultrafine particles), Dust (for fine particles), and Pollen (for coarse particles).

Explore the list of AHAM-certified air purifiers, complete with room size recommendations.