CRAC Unit Sizing Calculator
Precision cooling capacity and redundancy.
Enter your values
ⓘ Live results
Results
- Total heat load
- 85.3 kW
- In tons
- 24.3
- Units required
- 2 (N1)
- Capacity per unit
- 85.3 kW
- Airflow at 20°F rise
- 13,477 CFM
Quick answer
CRAC sizing totals IT load plus lighting, people and envelope gains, then adds redundancy.
total kW = IT + lighting + people + envelope
How to use the CRAC Unit Sizing Calculator
- 1Enter measured IT load from the PDUs, not nameplate ratings.
- 2Add room area so lighting and envelope gains are included.
- 3Choose the redundancy level your uptime target requires.
Worked example
Using the values the calculator loads with:
Inputs
- IT load40 kW
- Room area1200 sq ft
- People2
- RedundancyN+1
Results
- Total heat load85.3 kW
- In tons24.3
- Units required2 (N1)
- Capacity per unit85.3 kW
- Airflow at 20°F rise13,477 CFM
Frequently asked questions
Why not use nameplate?
Servers typically draw 40-60% of nameplate, so nameplate sizing wildly oversizes the plant.
N+1 vs 2N?
N+1 covers a single failure or maintenance; 2N gives fully independent paths for tier 3/4 designs.
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.