Rack power calculator
Enter the devices in one rack, the voltage, the breaker size and whether the rack is dual-fed. The calculator gives the rack load, the load on each PDU in normal operation, and the load on the surviving PDU when one feed fails, checked against the 80 % rule.
Rack power calculator
Enter the devices in one rack with their typical draw (measured if you have it, otherwise an estimate per model). Results are estimates.
| Device | Qty | Watts each |
|---|---|---|
| Rack load | |
|---|---|
| Breaker capacity (80 % rule) | |
| Each PDU, normal | |
| Surviving PDU if one feed fails |
For the method behind it, read rack power capacity planning with a spreadsheet and the 80 % rule. In DC Sim the same check runs for every rack, PDU, panel and UPS at once when you import the Power sheet, and Fail shows the result in 3D.
Why does the surviving PDU carry the whole rack?
In a 2N rack every device has one cord on feed A and one on feed B. When feed A fails, the B cords carry the full load, so the B PDU and its breaker must handle the whole rack under the 80 % rule.
Why 80 %?
A breaker, PDU or UPS should not carry more than 80 % of its rating continuously; the rest is margin for inrush, imbalance and measurement error. A 32 A breaker at 230 V is 7.36 kW, so about 5.9 kW is usable.
Which watts should I enter?
Measured draw if you have a week of readings; otherwise a per-model estimate. Nameplate ratings overstate most servers, but a flat percentage of nameplate hides the racks that really run hot.
One Excel file. Your room in 3D.
Fill in the Devices sheet and send it with your walkthrough request; we import it on the call. What each sheet does