Fan Array CFM Calculator
Total airflow and redundancy from a fan array.
Enter your values
ⓘ Live results
Results
- Total array airflow
- 40,000 CFM
- Airflow with redundancy fans down
- 35,000 CFM
- Design airflow needed
- 35,000 CFM (assumed)
- Per-fan share
- 12.5% of total
Quick answer
Total airflow equals the number of operating fans times each fan's rated CFM, and redundant arrays keep design airflow even with one fan down.
Total CFM = n x CFM_per_fan; N+1 CFM with one down = (n-1) x CFM_per_fan
How to use the Fan Array CFM Calculator
- 1Enter the number of fans in the array and the rated CFM per fan.
- 2Enter how many spare (redundant) fans are included in the design.
- 3Confirm the array still meets design airflow with the redundant fan(s) out of service.
Worked example
Using the values the calculator loads with:
Inputs
- Number of fans in array8
- CFM per fan5000 CFM
- Design redundancy1 fans
Results
- Total array airflow40,000 CFM
- Airflow with redundancy fans down35,000 CFM
- Design airflow needed35,000 CFM (assumed)
- Per-fan share12.5% of total
Frequently asked questions
Why use fan arrays instead of one big fan?
Arrays give built-in redundancy, easier maintenance, lower sound per fan and better part-load efficiency with VFDs.
How many spares are typical?
N+1 is common for critical spaces like data centers; N+2 for the most critical applications.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.