Cooling Capacity Calculator

Calculate cooling requirements from IT load, PUE, and airflow parameters for data center HVAC design.

Inputs

IT load (kW)

Power Usage Effectiveness (PUE)

Safety / growth factor (%)

Supply air temp (°F)

Return air temp (°F)

Sensible heat ratio

Tab to move between fields

Results

Design cooling capacity (tons)

54.59

Base cooling (tons)45.5

Total heat load (BTU/hr)545,942

Required airflow (CFM)12,006

CRAH units needed3

Chilled water flow (GPM)90.99

Overhead power (kW)60

Total facility power (kW)160

It Heat Btu Hr341,214

How to Use This Calculator

Enter the total IT load in kilowatts and the facility PUE.
Set the safety and growth factor percentage.
Input supply and return air temperatures for airflow calculations.
Review design cooling capacity in tons and number of CRAH units required.
Use chilled water GPM and total facility power to size the chiller plant.

How the result changes with IT load (kW)

IT load (kW)	Design cooling capacity (tons)
10,000	5,459.42
35,000	19,107.98
65,000	35,486.26
90,000	49,134.82

What each input means

IT load (kW): Total IT equipment electrical load in kilowatts.
Power Usage Effectiveness (PUE): Facility PUE. Industry average ≈ 1.58, efficient ≈ 1.2-1.4.
Safety / growth factor (%): Design margin for future growth and peak conditions.
Supply air temp (°F): Cold aisle supply air temperature. ASHRAE recommended: 64-80°F.
Return air temp (°F): Hot aisle return air temperature.
Sensible heat ratio: Fraction of heat that is sensible (vs. latent). Data centers are typically 0.9-1.0.

What each result means

Design cooling capacity (tons): Required cooling capacity including safety factor, in refrigeration tons.
Base cooling (tons): Minimum cooling capacity without safety margin.
Total heat load (BTU/hr): Total heat rejected by all facility equipment.
Required airflow (CFM): Cubic feet per minute of conditioned air needed.
CRAH units needed: Number of 25-ton CRAH/CRAC units required.
Chilled water flow (GPM): Chilled water flow rate at 12°F ΔT.
Overhead power (kW): Non-IT power consumption (cooling, UPS losses, lighting, etc.).
Total facility power (kW): IT load × PUE = total power draw.

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
IT load (kW) = 100, Power Usage Effectiveness (PUE) = 1.6, Safety / growth factor (%) = 20, Supply air temp (°F) = 55 = 6 input(s) provided
Calculate Design cooling capacity
Design cooling capacity = baseCoolingTons * safetyMultiplier
54.59 = 54.59
Calculate Base cooling
Base cooling = totalHeatBtuHr / 12000
45.5 = 45.5
Calculate Total heat load
Total heat load = totalFacilityKw * 3412.14
545942 = 545942

Engine last updated August 5, 2026.

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