Engineering Tools
Air Change Rate Calculator
Enter room dimensions and air change rate to instantly calculate the required airflow in CMH, CMM, and CFM. Suitable for ventilation system design and indoor air quality planning.
Ventilation Airflow Calculator
Calculation Results
Calculation Formula
This tool calculates the required ventilation airflow based on room volume and Air Changes per Hour (ACH). It is suitable for general ventilation system design and indoor air quality assessment.
Room Volume:
V = L × W × H (unit: m³)
Where L = Length, W = Width, H = Height (meters).
Required Airflow (CMH):
CMH = V × ACH (unit: m³/h)
Airflow Unit Conversion:
CMM = CMH ÷ 60 (unit: m³/min)
CFM = CMH × 0.5886 (unit: ft³/min)
ACH (Air Changes per Hour) is the number of complete air volume replacements per hour. Different space types have different recommended ranges. Actual design should consider regulatory requirements, occupancy density, heat load, and pollution sources.
Frequently Asked Questions
What is the Air Change Rate (ACH)?
ACH (Air Changes per Hour) refers to the number of times the entire volume of air in a room is completely replaced per hour. For example, ACH=6 means the air in the space is fully exchanged 6 times per hour. Different space types have different recommended values.
How do you convert between CMH and CFM?
CMH stands for m3/h (cubic meters per hour) and CFM stands for ft3/min (cubic feet per minute). 1 CMH = 0.5886 CFM, or 1 CFM = 1.699 CMH.
How many air changes does an office need?
A typical office requires ACH 4-6, and conference rooms require ACH 6-8. Spaces with special air quality requirements (such as laboratories or hospitals) may need ACH 6-15 or more.
Professional Consultation
Need Professional HVAC Engineering?
Online tools provide preliminary estimates for reference. Actual engineering design requires consideration of many additional professional factors. Contact our engineering team for precise HVAC system planning.