Ventilation / ACH Calculator
The Ventilation / ACH Calculator finds the required air changes per hour and supply airflow for a room from its function, area, and occupancy. Example: for a 150 m² office with 25 people and a 3.5 m ceiling, Required ACH = 6 /h, Supply airflow = 3150 m³/h, Supply airflow = 1854 CFM (per ASHRAE 62.1:2022 Ventilation Rate Procedure).
How it works
Computed from your inputs per ASHRAE 62.1:2022 Ventilation Rate Procedure.
Worked example (HVAC & Cooling)
Inputs: a 150 m² office with 25 people and a 3.5 m ceiling.
| Result | Value |
|---|---|
| Required ACH | 6 /h |
| Supply airflow | 3150 m³/h |
| Supply airflow | 1854 CFM |
Computed live by WorkHive's calculation engine; standard: ASHRAE 62.1:2022 Ventilation Rate Procedure.
How to use this calculator
- Enter the figures for the duty you are sizing: the worked example below uses a 150 m² office with 25 people and a 3.5 m ceiling.
- The calculator returns Required ACH, Supply airflow, Supply airflow, computed per ASHRAE 62.1:2022 Ventilation Rate Procedure.
- Check the worked example to confirm the method matches how you would do it by hand, then run your own numbers in the interactive tool.
FAQ
What is a air changes per hour ventilation calculator?
The Ventilation / ACH Calculator is a free online tool that computes finds the required air changes per hour and supply airflow for a room from its function, area, and occupancy. It shows the formula and a fully worked example so you can check the method, not just the number.
How is it calculated?
The result is computed from your inputs following ASHRAE 62.1:2022 Ventilation Rate Procedure. The worked example on this page shows a real computation with real numbers.
Is the calculator free?
Yes. WorkHive's engineering calculators are free to use, no sign-up needed for the tools. WorkHive is a free, offline-first maintenance platform built for Philippine industrial plants.
Run it on your own numbers
Open the interactive Ventilation / ACH Calculator in WorkHive: free, no sign-up needed for the calculators.