Rack Power & Cooling Calculator_
Enter a rack's power draw to get its heat load, recommended cooling method, estimated coolant flow or airflow, and 3-phase current at 415V/480V—plus total facility power across the hall.
Planning estimates. Heat load and 3-phase current are direct conversions; coolant flow and airflow depend on the actual ΔT, coolant, and CDU/CRAH design and are shown for the stated assumptions. Confirm against the OEM/CDU spec, the rack power summary, and your electrical design before any work.
Common questions_
How much heat does a GPU rack produce?
Effectively all of the rack's electrical power becomes heat. Heat load in BTU/hr is the rack power in kW times 3,412. A 120 kW rack rejects roughly 409,000 BTU/hr into the cooling system — which is why NVL72-class racks require direct-to-chip liquid cooling.
When does a rack need liquid cooling instead of air?
Low-density racks can be air-cooled; as density climbs past what raised-floor air and rear-door heat exchangers can remove, direct-to-chip liquid becomes required. GB200 and GB300 NVL72 racks are 100% liquid-cooled by design.
How do I size the electrical feed for a GPU rack?
Three-phase current is the rack power divided by (√3 × voltage × power factor). At 415V, a 120 kW rack draws on the order of ~168 A; feeders and breakers are sized above the continuous load per the electrical code. Confirm against the rack power summary and your electrical design.
How much coolant flow does a liquid-cooled rack need?
Flow follows Q = ṁ·cp·ΔT — it depends on the rack heat load, the coolant, and the supply/return temperature difference. This calculator estimates it for a water-glycol blend at a typical ΔT; the real value comes from the CDU and cold-plate spec.