When people compare chillers, the first thing they look at is the cooling capacity. But the confusing part is this: cooling capacity can show up in many different units. Sometimes it’s kW, sometimes it’s tons, sometimes it’s BTU/hr. And in many markets, people even use HP to describe “how powerful” a chiller is.
 
This guide gives you a simple explanation of the most common chiller cooling capacity units, what they represent, and how to convert between them.

Common Cooling Capacity Units

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Below are the units you will see most often in industrial refrigeration and process cooling. Each one describes how much heat the chiller can remove per hour.

1.kW (Kilowatts)

kW is the standard cooling capacity unit in most technical documents. It tells you how much heat the chiller can remove per second. It is simple, universal, and widely used in industrial standards.

2.kBTU/hr (Thousand BTU per Hour)

kBTU/hr is popular in the United States. It describes how many British Thermal Units the chiller removes in one hour.
 
1 kW ≈ 3.412 kBTU/hr.
 
People use it because it is easy to compare with HVAC equipment like rooftop AC units or heat pumps.

3.Tons of Refrigeration (TR / RT)

A “ton” is an old but still common unit in North America and parts of Asia. 1 refrigeration ton = the cooling needed to melt one ton of ice in 24 hours. Even today, engineers use it because it gives a quick sense of chiller size:
 
1 TR ≈ 3.517 kW ≈ 12 kBTU/hr.
 
If you see RT instead of TR, don’t worry. They mean the same thing.

4.HP (Horsepower, often misunderstood)

Technically, HP is not a cooling-capacity unit. It is a motor power unit. But many markets, especially in Asia, use HP as a simple way to estimate cooling size.
 
This leads to confusion.

A “5 HP chiller” does NOT mean “5 HP of cooling.” It means the compressor motor is 5 HP. The actual cooling capacity depends on design, refrigerant, operating conditions, and efficiency.
 
This is why HP should never be used as the main sizing unit for industrial chillers.

Why Cooling Units Matter for Chiller Performance

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Cooling capacity units are not just numbers. They influence how you choose and compare chillers.
 
■ Some regions only use tons.
■ Some industries specify in kW.
■ HVAC contractors may talk only in BTU/hr.
 
If you misunderstand the unit, you may size the chiller incorrectly. A 10-ton chiller is not the same as a 10 kW chiller, and a “5 HP chiller” tells you almost nothing about its true cooling output.
 
Choosing the wrong capacity can cause:
 
■ slow cooling
■ unstable temperatures
■ high energy cost
■ shorter equipment life
 
Knowing the units helps you evaluate performance more clearly and avoid costly mistakes.

How to Convert Between Cooling Capacity Units

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These are the only conversions you really need:
 
■ 1 kW = 3.412 kBTU/hr
■ 1 kW = 0.284 TR
■ 1 TR = 3.517 kW = 12 kBTU/hr
■ 1 kBTU/hr = 0.293 W
 
A simple rule you can remember:
1 refrigeration ton ≈ 3.5 kW.
 
Once you know this, comparing chillers becomes much easier.

HP Conversion and Misconceptions

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HP is the most confusing “unit” in the cooling world, because people use it differently by region.
Here are the facts:
 
1.HP is motor power, not cooling capacity.
Two 5 HP chillers can have very different cooling outputs.
 
2.There is no exact universal conversion.
But some markets use rough estimates like:
 
■ 1 HP ≈ 0.75–0.9 kW cooling
■ 1 HP ≈ 2,500–3,000 kcal/hr
■ 1 HP ≈ 8,500–10,000 BTU/hr
 
3.The actual capacity depends on compressor type, COP, refrigerant, and temperature.
 
If you want accurate cooling capacity, always look for:
 
■ kW
■ TR
■ kBTU/hr
 
Never size an industrial chiller based on HP alone.

Quick Reference Table

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This small table helps you navigate most specification sheets and compare chillers across regions.

Unit	Common Meaning	Approximate Equivalent
1 kW	Standard cooling power	3.412 kBTU/hr
1 TR / RT	One ton of refrigeration	3.517 kW or 12 kBTU/hr
1 kBTU/hr	U.S. HVAC unit	0.293 kW
HP (motor power)	Not a cooling-capacity unit	No fixed conversion

How to Calculate Chiller Cooling Capacity

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Because we already wrote a complete guide on this topic, here is the short version.
 
Chiller cooling capacity mainly depends on:
 
■ the flow rate of the coolant
■ the temperature difference (delta T/ΔT)
■ the fluid properties
 
The basic idea is simple:
More flow + bigger temperature drop = higher cooling capacity.
 
If you want the full formulas and examples, you can check the detailed article “How to Calculate Chiller Cooling Capacity.”

Conclusion

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Understanding chiller cooling capacity units is one of the easiest ways to avoid oversizing or undersizing your cooling system. Once you get familiar with kW, TR, and kBTU/hr and understand why HP is misleading, you can compare chillers much more confidently.
 
If you are choosing a new industrial chiller or upgrading your current cooling system, our team at LNEYA can help you select the right capacity and the right unit for your application. A well-sized chiller keeps your process stable, protects your equipment, and reduces long-term operating costs.