Cleanroom engineering tool

Cleanroom ACH & airflow calculator

Find air changes per hour from a known supply airflow, or estimate the supply airflow needed for a target ACH. Enter your room dimensions and get an immediate result in m³/h and CFM.

Calculate your airflow

Results update as you type.

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Room dimensions

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m
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Known supply airflow

Use the room's design dimensions and the supply airflow delivered to the room. This is a preliminary volumetric calculation.

How the calculation works

Air changes per hour (ACH) compares the volume of air supplied to a room in one hour with the room's volume. For a rectangular room, calculate volume from length, width, and height. Enter supply airflow in m³/h or CFM; the calculator converts units automatically.

Room volume (m³) = length × width × height
ACH = supply airflow (m³/h) ÷ room volume (m³)
Required airflow (m³/h) = target ACH × room volume (m³)

For example, an 8 m × 6 m × 3 m room has a volume of 144 m³. At a supplied airflow of 3,600 m³/h, its calculated air change rate is 25 ACH. A target of 25 ACH for the same room requires 3,600 m³/h, or about 2,119 CFM.

Using the result in a cleanroom project

This result describes theoretical air volume turnover. It does not establish an ISO cleanliness class or replace cleanroom design, commissioning, and particle measurements. ISO 14644-1 classifies air cleanliness by airborne particle concentration. The airflow selected for a project also depends on the process, particle sources, airflow pattern, occupancy, pressure relationships, and equipment.

For a design decision, confirm the target ACH and measured supply airflow with a qualified cleanroom engineer. Unidirectional airflow zones may be evaluated using face velocity rather than a room ACH target.

Discuss your cleanroom project

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