Chiller Tonnage Calculator (TR from Flow & ΔT)
By Santaji GadepatilinUpdated November 5, 2026
A chiller's cooling load is the heat the chilled water picks up: mass flow × specific heat × temperature rise. This chiller tonnage calculator turns flow and ΔT into kW and tons of refrigeration (1 TR = 3.517 kW) — see the step-by-step guide to calculating industrial chiller capacity.
How to use the chiller tonnage calculator
Enter the chilled water flow, the temperature difference between return and supply water, and the fluid’s specific heat and density (defaults are water). The calculator gives the cooling load in kW and in tons of refrigeration. To size the flow for a known load, clear the flow and enter the tonnage.
Chiller capacity formula
Q = ρ × V̇ × cp × ΔT · TR = Q (kW) ÷ 3.517
Worked example
50 m³/h of water returning at 12 °C and supplied at 7 °C (ΔT = 5 K):
- Mass flow = 998 × 50 ÷ 3,600 = 13.86 kg/s
- Q = 13.86 × 4,186 × 5 = 290.1 kW
- Capacity = 290.1 ÷ 3.517 = 82.5 TR
Chiller capacity (TR) by flow and ΔT (water)
| Flow | ΔT 4 K | ΔT 5 K | ΔT 6 K | ΔT 8 K |
|---|---|---|---|---|
| 10 m³/h | 13.2 | 16.5 | 19.8 | 26.4 |
| 25 m³/h | 33.0 | 41.2 | 49.5 | 66.0 |
| 50 m³/h | 66.0 | 82.5 | 99.0 | 132.0 |
| 100 m³/h | 132.0 | 165.0 | 198.0 | 264.0 |
| 200 m³/h | 264.0 | 330.0 | 396.0 | 528.0 |
| 500 m³/h | 659.9 | 824.9 | 989.9 | 1319.9 |
Notes
- Add a design margin of 10–20% and allow for pump heat and pipe heat gains.
- Comfort cooling usually uses 7 °C supply / 12 °C return (ΔT 5 K); process chillers vary.
Frequently asked questions
How do I calculate chiller tonnage?
Cooling load Q = ρ × flow × cp × ΔT. Divide the result in kW by 3.517 to get tons of refrigeration. 50 m³/h of water with a 5 K rise is about 290 kW or 82.5 TR.
What is the GPM formula for chiller tons?
Tons = GPM × ΔT(°F) ÷ 24 for water. It comes from 500 × GPM × ΔT BTU/h divided by 12,000 BTU/h per ton.
How much is 1 ton of refrigeration?
12,000 BTU/h = 3.517 kW — the heat needed to melt one short ton of ice in 24 hours.
What about glycol?
Use the glycol mixture's specific heat and density. 30% ethylene glycol has cp ≈ 3,700 J/kg·K, so it carries about 10% less heat than water at the same flow and ΔT.