Penton Systems / Tools / Power
Free tool · facilitiesRack power, heat and UPS
Before you plug in another server: how many amps, how many circuits, how much heat the room has to remove, what it costs a year, and how long the UPS holds. The rack fills as you add machines and each gauge is one circuit.
Calculator
This calculator needs JavaScript. The formulas are listed below.
Three equations run every rack
- 01
Electrical
VA = watts / power factor. Amps = VA / volts. Usable capacity of a circuit for continuous load = volts × breaker amps × 0.8 × power factor.
- 02
Heat and cooling
Every watt becomes heat: BTU per hour = watts × 3.412. One ton of cooling removes 12,000 BTU per hour. This is the load your cooling must handle, before other heat sources in the room.
- 03
Cost and UPS
kWh per year = watts × 8.76. UPS runtime = battery watt-hours × efficiency / load watts. Real runtime falls with battery age, temperature and high load, so treat it as a best case.
- 04
Code and safety
Loading continuous circuits to no more than 80 percent of their rating is common practice. Confirm local electrical code and have a qualified electrician verify any real installation.
Plan power, cooling and hardware together
We will be honest about what an older server really costs to run, and size the circuits, UPS and cooling with you.