Air Changes Per Hour (ACH) Calculator

For specific air changes per hour calculations; adjust the room dimensions to match your own (If the calculator did not load, please refresh your page).

MedicAir® Air Changes Per Hour Calculator

The MedicAir® is a medical-grade HEPA air purifier that is extremely easy to maintain with a simple swap of a single all-in-one cartridge housing a HEPA H13 Filter, Activated Carbon Filter, and Ultra-Violet Type-C light. The MedicAir® is used in thousands of medical offices, and commercial offices, globally.

What is the ACH calculator for?

It is designed to calculate the air change rate of ventilation systems, air purifiers, HVAC systems, and more on specific room sizes. This calculator has become popular due to the growing demand for indoor air quality air purifiers since the COVID-19 outbreak. This calculator is not used to measure fresh air, the external volume of air, or the CADR rating (Clean air delivery rate) of your specific air purifier for that you should consult the air purifier product manual.

The calculation is based on the size of the room, ceiling height, width, and length in feet to calculate the ACH. For simplicity, the calculations and breakdowns of cubic feet per minute, CFM variable adjustments, and HVAC-related ventilation rates are not shown or used.

What is the recommended ACH, Air Changes Per Hour?

In Medical Environments, the recommended ACH is 10 Air Changes Per Hour.

In Commercial Environments, the recommended ACH is 5 Air Changes Per Hour.

Calculating Air Changes Per Hour (ACH):

  1. Calculate the room size (Height, Width, & Length) - Example: 25ft x 20ft x 8ft room = 4,000 FT³ (Cubic Feet)

  2. Know the CFM or CADR of the air purifier, and convert it to cubic feet per hour. - Example: The CADR of the MedicAir® is 605. 605 x 60 (minutes) = 36,300 CFH (Cubic Foot Per Hour)

  3. Find the ACH by dividing Step 2 by Step 1: 36,300 / 800 = 9.075 ACH