Chiller Size Calculator
Enter the water flow, the inlet and outlet temperatures and a safety factor. The calculator gives the chiller size in tons and kW, the load in BTU per hour and a standard size.
- Chiller size
- Load
- Standard size
Inlet is the warm water coming back from the process.
Tons = gpm × temperature drop in °F ÷ 24. Cooling 20 gpm of water from 60 °F to 50 °F is a load of 8.3 tons. With a 20% safety factor, choose a 10 ton chiller, about 35 kW.
Chiller size chart
10 °F drop, 20% added. Search for flow.
| Flow (gpm) | Load (tons) | With 20% (tons) | kW |
|---|---|---|---|
| 5 | 2.1 | 2.5 | 9 |
| 10 | 4.2 | 5 | 18 |
| 20 | 8.3 | 10 | 35 |
| 30 | 12.5 | 15 | 53 |
| 50 | 20.8 | 25 | 88 |
| 75 | 31.2 | 37.5 | 132 |
| 100 | 41.7 | 50 | 176 |
| 150 | 62.5 | 75 | 264 |
| 200 | 83.3 | 100 | 352 |
Tons.
Flow and chiller
10 °F drop, 20% added. Slide the flow.
The chiller grows with the load.
How to size a chiller
Flow to tons. Step through it.
Flow
gpm.
Insulate chilled water pipes to stop condensation.
Air cooled or water cooled
Chiller types. Compare them.
Simple.
Efficient.
Process.
Water cooled chillers are more efficient but need a cooling tower.
Before you buy
Chiller checks. Tick each item.
Tick each item as you go.
Check the rating at your hottest ambient temperature.
What you get
Chiller sizing. Each tile explains one result.
Cooling.
Cooling.
BTU/h.
gpm.
Air or water.
One ton of cooling is 12,000 BTU per hour, or 3.517 kW.
Frequently Asked Questions
No question matches that search.
How do I size a chiller?
Multiply the flow in gallons a minute by the temperature drop in Fahrenheit and divide by twenty four.
What size chiller for twenty gpm?
About eight tons at a ten degree drop, ten tons with a safety factor.
What is a ton of cooling?
Twelve thousand BTU per hour, about three point five kilowatts.
Why add a safety factor?
To cover heat gains, fouling and hot days.
Does glycol change the chiller size?
Yes. Glycol carries less heat, so you need more flow or a bigger chiller.
Air cooled or water cooled?
Air cooled for smaller sizes, water cooled for large efficient plants.
How do I size a chiller in kilowatts?
Litres a minute times the drop in Celsius times point zero six nine seven.
Cool enough, not too much
Size the chiller to your flow and temperatures and it holds your process steady.
More size calculators
Each one has its own calculator, worked examples and answers to common questions.