Air Change Rate (ACH) Calculator

Enter room volume and airflow rate to calculate ACH. Results update in real-time.

The Air Change Rate (ACH) Calculator (ACH Calculator) is used to determine how many times the air within a defined space is replaced over a one-hour period. This metric is crucial for assessing ventilation effectiveness, designing ventilation systems, and ensuring indoor air quality. Inputs for this calculation are the room volume (in cubic feet) and the total airflow rate supplied to or exhausted from the room (in Cubic Feet per Minute - CFM). Understanding ACH helps in various applications, from residential homes to specialized environments like laboratories or healthcare facilities.

ACH vs. CFM: While related, they are different. ACH (Air Changes per Hour) measures how many times the total air volume in a room is replaced within one hour. It's an indicator of ventilation effectiveness for a specific space. CFM (Cubic Feet per Minute) measures the volume of air moved by a fan or ventilation system per minute; it's a rate of airflow. ACH depends on both the CFM of the ventilation system and the volume of the room. A high CFM in a small room will result in a high ACH, while the same CFM in a large room will yield a lower ACH.

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Important Disclaimer

This calculator determines ACH based on provided airflow. It does not design the ventilation system or specify required ACH for a particular application. Consult relevant standards and professionals for ventilation design.