HVAC CFM Calculator

HVAC CFM Calculator

HVAC CFM Calculator

Calculate the Cubic Feet per Minute of your HVAC system and get the accurate air flow requirement for every room!

Use our HVAC CFM Calculator to calculate your rooms’ optimum air circulation rate and maintain a high indoor air quality.

What is a CFM calculator?

An HVAC CFM calculator is an essential tool for calculating the airflow volume through your heating, ventilation, and air conditioning system. It ensures the proper circulation of airflow needed for your room and maintains indoor air quality.

These calculators are valuable tools that help HVAC or air conditioning engineers compute and ensure your equipment is correctly sized and configured to maintain the correct temperature in your desired space.

Why is CFM calculation essential?

CFM, or cubic feet per minute calculation, is essential because it ensures comfort in your indoor surroundings by maintaining the required air circulation. These calculations help HVAC engineers determine the accurate measurements of the airflow needed to maintain an optimum temperature, save on energy, and enable maximum comfort for occupants.

How do you calculate CFM?

To calculate CFM for your HVAC system, you need to consider various factors, such as the length, width, and height of your room.

Follow the below steps to calculate the CFM of your room:

Step 1: Calculate Your Room Dimensions.

Calculating your room dimensions requires measuring the following:

  • The room width
  • The room length
  • The ceiling height

Step 2: Find Out ACH

Decide on the required ACH level of your room. ACH or air changes per hour is the air velocity rate at which the air changes in an hour. Basically, it’s the rate at which fresh air inside a room changes per hour.

ACH is calculated by determining the frequency at which air volume in a space is exchanged in an hour. It depends on factors like the room’s purpose, occupancy, and air quality requirements. It is also determined based on the volume of the room, the airflow rates, and your desired air quality standards.

Step 3: Convert Square feet to CFM

First, calculate the room size in square feet by multiplying the width and length of the room.

Now, Calculate the room volume by multiplying the room size by the ceiling height.

Then, multiply the room volume by ACH.

Finally, divide the total by 60 to get the required CFM for your room.

HVAC CFM Requirements Calculation Example

Room width = 15ft

Room length = 12ft

Ceiling height = 9ft

Let’s consider the desired ACH 6.


Here comes the calculation,

Room size in square feet = (15×12) = 180 square feet.

Room volume in cubic feet = (180×9) = 1620 cubic feet

Now multiplying the room volume by ACH = 1620x 6 = 9720


In the last step, divide the total by 60 = 9720/60 = 162 CFM


Hence, the total CFM requirement for your space is 162. 

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