CFM Calculator

Room Dimensions
Floor Area:
Airflow Requirements
Air changes per hour (ACH):

CFM (Cubic Feet per Minute) is a unit of measurement used to quantify the amount of air flow in a given space. It represents the volume of air that is circulated or exchanged in one minute. Understanding the CFM requirements is essential for ensuring proper ventilation and maintaining good air quality in various environments.

The air changes per hour (ACH) is a significant factor in determining the appropriate CFM rate. ACH refers to the number of times the air within a room or building is replaced with fresh air within one hour. The desired ACH value depends on the specific space and its intended use. Different environments, such as residential areas, commercial buildings, or specialized facilities, have varying ACH recommendations to meet specific air quality standards.

Recommended Air Changes per Hour by Room Type

Building/Room Air Changes per Hour (ACH)
Basements 3-4
Bedrooms 5-6
Bathrooms 6-7
Living rooms 6-8
Kitchens 7-8
Laundry room 8-9
Offices 6-8
Business offices 6-8
Cafeterias 7-12
Conference rooms 8-12
Medical procedure offices 9-10
Copy rooms 10-12
Main computer rooms 10-14
Smoking area 13-15
Dining area 8-10
Food staging 10-12
Kitchens 14-60
Bars 15-20
Public places
Hallways 3-5
Waiting rooms 4-8
Banks 4-8
Hospital wards 6-8
Gyms 6-10
Malls and retail stores 6-10
Restrooms 6-15
Classrooms 6-20
Foyers 8-10
Houses of Worship 8-12
Theaters and auditoriums 8-15
Restrooms 10-12
Swimming pools 10-15
Hospital facilities 10-20
Auditoriums 12-14
Smoking rooms (Don't⚠️) 15-20


Further reading:

Falke, R. "Use the Air Changes Calculation to Determine Room CFM." Contracting Business, 24 Mar. 2016.