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Chiller Sizing Calculator

Commercial Cooling · Tons · kW · Chilled Water GPM

When to use: Use to estimate the chiller plant capacity for commercial buildings — offices, hospitals, schools, and data centers. Enter floor area, occupancy, and internal loads to size the chiller in tons of refrigeration. Includes diversity and redundancy factors, electrical demand (kW), chilled water flow rate (GPM), and cooling tower sizing. For final design, perform a full ACCA Manual J or ASHRAE load calculation.

Building Parameters
ft²
floors
people
1–3 W/ft²
W/ft²
Office: 5–10, Lab: 20–50
W/ft²
Chiller Selection
0.75–0.95 typical
(0–1)
1.1–1.25
(×)
Design Chiller Capacity
78.3
Tons of Refrigeration
15,000 ft² total conditioned area
System Summary
Peak Cooling Load62.7 tons (751,970 BTU/hr)
Design Capacity (w/ redundancy)78.3 tons
Electrical Demand47 kW
Efficiency (kW/ton)0.61 kW/ton
Chilled Water Flow188 GPM
Cooling Tower Sizing97.9 tons (heat rejection)
References
ASHRAE 90.1 – Chiller minimum efficiency standards
1 ton = 12,000 BTU/hr cooling capacity
CHW GPM = tons × 2.4 (at 10°F ΔT)
Cooling tower = chiller tons × 1.25 (heat rejection)