1. What is CFM Calculation?

CFM (Cubic Feet per Minute) is a measurement of airflow volume. It represents the amount of air that flows through a specific area in one minute. Calculating CFM from FPM (Feet per Minute) and area is essential in HVAC systems, ventilation design, and industrial applications.

2. How Does the Calculator Work?

The calculator uses the CFM formula:

Where:

• \( FPM \) — Feet per minute (velocity of airflow)
• \( Area \) — Cross-sectional area in square feet
• \( CFM \) — Cubic feet per minute (volume of airflow)

Explanation: This formula calculates the volume of air moving through a space by multiplying the air velocity (FPM) by the cross-sectional area of the duct or opening.

3. Importance of CFM Calculation

Details: Accurate CFM calculation is crucial for proper ventilation system design, ensuring adequate air exchange rates, maintaining indoor air quality, and optimizing energy efficiency in HVAC systems.

4. Using the Calculator

Tips: Enter FPM in feet per minute and area in square feet. Both values must be positive numbers. The calculator will compute the CFM (cubic feet per minute) result.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between CFM and FPM?
A: FPM measures air velocity (speed), while CFM measures air volume flow rate. CFM = FPM × Area.

Q2: How do I measure FPM accurately?
A: Use an anemometer to measure air velocity at multiple points across the duct and calculate the average FPM.

Q3: What is a good CFM rate for ventilation?
A: Recommended CFM varies by application. Residential bathrooms typically need 50-100 CFM, while kitchen range hoods may require 100-400 CFM depending on stove size.

Q4: Can I use this for rectangular ducts?
A: Yes, calculate area as width × height (in feet) for rectangular ducts, or π × radius² for circular ducts.

Q5: How does CFM relate to air changes per hour?
A: Air changes per hour = (CFM × 60) / room volume. This helps determine how frequently the air in a space is completely replaced.