PDU Load Calculator
Calculate PDU utilization percentage from connected equipment load against rated PDU capacity, with 80% derating guidance.
Inputs
Sum of actual (or nameplate) power draw of all equipment plugged into the PDU
PDU Utilization
60.0%
Status
Within safe operating range
Headroom to 80% Derating Threshold
1,000.0W
Headroom to Rated Maximum
2,000.0W
Step by step
Values used
Connected Load = 3,000 W; PDU Rated Capacity = 5,000 W
PDU utilization
utilization% = connected_watts / pdu_capacity_watts × 100
PDU Utilization
= 60.0
Status
= Within safe operating range
Headroom to 80% Derating Threshold
= 1,000.0 W
Headroom to Rated Maximum
= 2,000.0 W
How it works
PDU utilization compares connected equipment load against the unit's rated capacity, but continuous loads — like always-on server equipment — should be kept at or below 80% of that rating, the standard electrical derating margin that leaves headroom for inrush current and avoids nuisance breaker trips. Utilization above 80% is a warning sign even if the PDU hasn't tripped yet; above 100% risks an overload trip.
Formula
PDU utilization
utilization% = connected_watts / pdu_capacity_watts × 100
Frequently Asked Questions
Why is 80%, not 100%, treated as the practical limit?
Continuous electrical loads are conventionally derated to 80% of a circuit or PDU's rating (an NEC-style convention) to leave margin for inrush current at power-on, temperature effects on conductors, and to avoid nuisance breaker trips under sustained load — the PDU's 100% rating is a hard ceiling, not a comfortable operating point.
Should I use nameplate power or measured power draw?
Nameplate (rated) power is a conservative upper bound and useful for initial planning, but measured/metered draw reflects real utilization more accurately, since equipment rarely runs at full nameplate power continuously. Use metered PDU data when available for capacity planning decisions.
How do I reduce PDU utilization?
Redistribute equipment across additional PDUs or circuits, migrate to more power-efficient hardware, or verify actual draw with a metered PDU rather than relying on conservative nameplate ratings that may overstate real load.