This server room cooling calculator estimates the total heat your cooling must remove: not just the IT load, but also UPS and power distribution losses, lighting and the people working in the room. It runs entirely in your browser: nothing you type is sent to our server.
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Table of Contents
The method
It follows the simple method in Schneider Electric (APC) White Paper 25, “Calculating Total Cooling Requirements for Data Centers”, for rooms up to about 4,000 ft² (372 m²):
| Heat source | Heat output |
|---|---|
| IT equipment | Same as its power draw |
| UPS with battery | 0.04 × power system rating + 0.05 × IT load |
| Power distribution | 0.01 × power system rating + 0.02 × IT load |
| Lighting | 2.0 W per ft² (21.53 W per m²) |
| People | 100 W per person |
APC’s own example, a 250 kW power system loaded with 75 kW of IT and up to 20 people, comes to about 105 kW of total heat. With a 5,000 ft² room the calculator gives 104.8 kW.
Before you buy cooling
- Add heat from sun, outside walls and windows (Other heat field) if the room has them.
- APC also advises cooling capacity of about 1.3 × the IT load plus redundancy, to allow for humidity control and imperfect air mixing; the calculator shows both figures.
- Plan redundancy (N+1) so one unit can fail or be serviced, and have an HVAC engineer confirm the final size.
How we checked it
We reproduced APC’s worked example on 11-12 October 2026: 75 kW IT, a 250 kW power system, 20 people and 5,000 ft² gives 104.8 kW (APC: about 105 kW).
To see how much of the room's power goes to cooling and other overhead, use the PUE Calculator.
Frequently asked questions
How do I calculate the cooling needed for a server room?
Add the IT load to the heat from UPS and power distribution losses, lighting and people, then convert kW to BTU/h (× 3,412) or tons (÷ 3.517). The calculator does this with APC’s rules.
How many BTU per person in a server room?
About 100 W, or roughly 340 BTU/h, per person in APC’s method.
Is office air conditioning enough for a server room?
Usually not: comfort units are built for people, cycle on and off, and are not designed to run 24/7 at full sensible load. Use close-control or precision cooling for anything more than a few kW.