Rack Cooling Airflow Calculator
Per-rack CFM for a server cabinet.
Enter your values
ⓘ Live results
Results
- Rack airflow needed
- 790 CFM
- Heat output
- 17,060 BTU/hr
- Tiles at 400 CFM each
- 2
- Watts per CFM
- 6.33
Quick answer
A typical server rack needs roughly 160 CFM per kW at a 20F rise, so a 5kW rack needs about 800 CFM.
CFM = (W x 3.412) / (1.08 x dT)
How to use the Rack Cooling Airflow Calculator
- 1Enter the rack's total power draw in watts.
- 2Choose the allowable delta-T across the rack, commonly 20F.
- 3Match perforated tile or in-row airflow to the result.
Worked example
Using the values the calculator loads with:
Inputs
- Rack power draw5000 W
- Delta T20 F
Results
- Rack airflow needed790 CFM
- Heat output17,060 BTU/hr
- Tiles at 400 CFM each2
- Watts per CFM6.33
Frequently asked questions
What if racks vary a lot?
Calculate each rack separately, then balance tiles or dampers to match hot spots.
High density racks?
Above 10kW/rack, in-row or rear-door cooling usually beats raised-floor tiles.
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.