Chiller Tonnage Calculator
Screen industrial chilled-water chiller tons from GPM × ΔT—or from a known cooling load—before OEM selection software.
Last reviewed:
Quick Calculator
Defaults: 480 GPM · 10 °F ΔT · SF 1.15. Results update instantly.
Advanced — safety / redundancy
About this calculator
Industrial CHW plant tonnage screen after you know cooling load from the HVAC size calculator. Browse all HVAC tools on the HVAC Calculators hub. Not OEM chiller selection, IPLV modeling, or glycol corrections.
Quick reference — GPM × ΔT → tons
| GPM | ΔT (°F) | Base tons | With SF 1.15 |
|---|---|---|---|
| 240 | 10 | 100 | 115 |
| 480 | 10 | 200 | 230 |
| 720 | 10 | 300 | 345 |
| 200 | 12 | 100 | 115 |
At 10 °F ΔT, ~2.4 GPM/ton. Raising ΔT reduces flow for the same tons (and vice versa).
Formula & explanation
Tons = GPM × ΔT (°F) × 500 ÷ 12,000 (equivalently GPM × ΔT ÷ 24).
From load: Tons = BTU/h ÷ 12,000, then multiply by your documented safety factor.
Best for: industrial / commercial CHW plant concept screens, process chillers with known flow and temperatures.
Not ideal for: residential SEER shopping, Manual J room loads alone, glycol systems without property corrections, or OEM IPLV / part-load selection.
Start facility load on HVAC capacity; psychrometrics on psychrometric calculator; plant kW screen via energy estimator / factory load.
Worked example
Process loop: 480 GPM, supply–return 10 °F, planning SF 1.15.
- Base tons = 480 × 10 × 500 ÷ 12,000 = 200 TR
- With SF: 200 × 1.15 = 230 TR
- At 10 °F ΔT check: 230 × 2.4 ≈ 552 GPM if you size flow from tons instead
Next: confirm building/process load with HVAC size, then electrical demand on the plant bus.
FAQ
How do you calculate chiller tonnage from GPM?
Tons = GPM × ΔT (°F) × 500 ÷ 12,000. Example: 480 GPM × 10 °F → 200 tons before safety factor.
What is the difference between chiller tons and HVAC capacity tons?
HVAC capacity screens facility/zone load intensity. This page screens CHW plant capacity from flow and ΔT (or a known plant load).
How much GPM per ton of chiller?
At 10 °F ΔT, about 2.4 GPM/ton. Different ΔT changes the ratio.
Should I oversize the chiller by 20%?
Prefer an explicit, documented factor (and N+1 studies) over a blank 20%. Oversizing can hurt part-load efficiency.
Does this replace manufacturer software?
No. Use OEM selection for evaporator/condenser conditions, glycol, IPLV, and electrical data.