Server Room Cooling Load Calculator

Quickly size server-room cooling by rolling up IT power draw, lighting, and occupancy. The calculator converts everything into BTU per hour, applies growth and redundancy buffers, and suggests the cooling tonnage and airflow needed to hold your design delta-T.

Sum the nameplate or measured kW for racks, UPS losses, and network gear.
Include overhead lighting, monitors, and other non-IT heat sources.
Count technicians present during peak periods.
Capture humidification, envelope gains, or external air leakage if known.
Adds capacity for load growth or hot spots. Leave blank for 20%.
Allow N+1/N+N resilience to keep temperatures in range during failures.
Typical server rooms run 18–22°F delta between supply and return air.

Engineering approximation—validate final HVAC design with a mechanical engineer.

Examples

  • 12 kW IT, 600 W lighting, 1 technician, 20% growth, 15% redundancy ⇒ ~57,060 BTU/h (≈4.75 tons) and 2,642 CFM at 20°F ΔT
  • 18 kW IT, 900 W lighting, 3 technicians, +1,500 BTU/h extras ⇒ ~88,488 BTU/h (≈7.37 tons) with 4,552 CFM at 18°F ΔT

FAQ

How should I treat diversity or part-load?

Most operators size on peak concurrent load to protect uptime. If monitoring shows diversity, dial back the growth allowance or incorporate economizer hours to reflect part-load efficiency.

What redundancy factor should I use?

Common designs use N+1 (≈15%) for single rooms and N+N (≈100%) for critical data centers. Adjust the reserve percentage to match your SLA and UPS backup strategy.

Does this cover humidity control?

The calculator focuses on sensible cooling. If you introduce outside air or need strict humidity control, add latent loads from humidifiers or dehumidifiers into the UPS/infiltration field.

Can I include hot aisle containment?

Yes—if containment improves return-air temperature, lower the ΔT input or reduce growth allowance to reflect higher efficiency.

Additional Information

  • 1 kW of IT power produces roughly 3,412 BTU/h of heat that must be removed to maintain thermal equilibrium.
  • Allow at least 400 BTU/h per person for sensible heat plus any diagnostic gear they bring into the white space.
  • Check raised-floor leakage, cable penetrations, and humidity systems—latent loads add to sensible heat removal needs.
  • Monitor actual rack power draw with metered PDUs to refine the IT kW input and calibrate future growth allowances.

Related calculators