CFM stands for Cubic Feet per Minute, which is a measure of air flow volume. It indicates how much air a fan or ventilation system can move in one minute.

CFM Calculator

Q: How do I calculate CFM?

Multiply the room volume (length × width × height) by the desired air changes per hour, then divide by 60 to convert to minutes. The formula is: CFM = (Room Volume × Air Changes per Hour) / 60.

Q: What are air changes?

Air changes refer to the number of times the entire room's air volume is replaced per hour. Different room types require different air change rates for proper ventilation and air quality.

Q: How do I choose a fan?

Select a fan with a CFM rating higher than your calculated requirement. Consider factors like room usage, local building codes, and future modifications when choosing fan size.

Q: What are code requirements?

Local building codes specify minimum ventilation requirements for different room types. Kitchens and bathrooms typically require higher air change rates than living rooms and bedrooms.

Room Parameters

Length

Length of the room

Width

Width of the room

Height

Height of the room

Room Type

Type of room

Air Changes per Hour

Desired air changes per hour (default: 6)

Calculation Results

CFM Calculator: Your Complete Guide to Air Flow Requirements

Proper air flow calculation is crucial for maintaining indoor air quality and comfort. Our CFM Calculator helps you determine the required air flow for your space.

Understanding CFM Requirements

Proper air flow is essential for several reasons:

Air Quality: Removes pollutants and odors
Comfort: Maintains temperature and humidity
Health: Reduces airborne contaminants
Energy Efficiency: Optimizes HVAC performance
Code Compliance: Meets ventilation requirements

How to Use the CFM Calculator

Enter Room Dimensions: Input length, width, and height
Select Room Type: Choose room purpose
Enter Air Changes: Specify desired changes per hour
Click Calculate: Get required CFM

CFM Calculation Formulas

Basic CFM Formula:
CFM = (Room Volume × Air Changes per Hour) / 60
Where:
Room Volume = Length × Width × Height
Air Changes = Desired air changes per hour
60 = Minutes in an hour

Common Room Types and Requirements

Living Room:
- Air Changes: 6-8 per hour
- CFM per Person: 15-20
- Minimum CFM: 100
Bedroom:
- Air Changes: 4-6 per hour
- CFM per Person: 15-20
- Minimum CFM: 50
Kitchen:
- Air Changes: 8-10 per hour
- CFM per Person: 20-25
- Minimum CFM: 150
Bathroom:
- Air Changes: 8-10 per hour
- CFM per Person: 20-25
- Minimum CFM: 50
Office:
- Air Changes: 6-8 per hour
- CFM per Person: 15-20
- Minimum CFM: 75

Real-World Examples

Example 1: Standard Living Room

Length: 20 feet
Width: 15 feet
Height: 8 feet
Room Type: Living Room
Air Changes: 6 per hour
Results:
- Room Volume: 2,400 cu ft
- Required CFM: 240
- Air Changes: 6 per hour
- Recommended Fan Size: 250 CFM

Example 2: Kitchen

Length: 15 feet
Width: 12 feet
Height: 8 feet
Room Type: Kitchen
Air Changes: 8 per hour
Results:
- Room Volume: 1,440 cu ft
- Required CFM: 192
- Air Changes: 8 per hour
- Recommended Fan Size: 200 CFM

Frequently Asked Questions

What is CFM?

Cubic Feet per Minute, a measure of air flow volume.

How do I calculate CFM?

Multiply room volume by desired air changes per hour, then divide by 60.

What are air changes?

Number of times the entire room's air is replaced per hour.

How do I choose a fan?

Select a fan with CFM rating higher than calculated requirement.

What are code requirements?

Follow local building codes for minimum ventilation requirements.