BTU to HP | BTU to Ton | BTU to kW | Conversion Tables


Many people get confused about BTU, Ton, HP, and kW used in air conditioning. What are they and what are their differences?

BTU, Ton, HP, and kW are the different units of measurement for the cooling capacity of an air conditioner. Most people refer to the cooling capacity of an air conditioner as BTU and Ton while some people prefer to use HP and kW when referring to the cooling capacity of an air conditioner.

Although all 4 units of measurement are referring to the same thing, each unit has a different number and they are all interchangeable through conversion as below tables.

Cooling Capacity Conversion Tables

  • 1 kW = 3,412 BTU
  • 12,000 BTU = 1 Ton
Main Unit (BTU)Equivalent HPEquivalent TonEquivalent kW
9,000 BTU1.0 HP0.75 Ton2.63 kW
12,000 BTU1.5 HP1.00 Ton3.51 kW
18,000 BTU2.0 HP1.50 Ton5.27 kW
24,000 BTU2.5 HP2.00 Ton7.03 kW
From BTU to other units
Main Unit (HP)Equivalent BTUEquivalent TonEquivalent kW
1.0 HP8,500 – 9,500 BTU0.70 – 0.79 Ton2.49 – 2.78 kW
1.5 HP11,500 – 12,500 BTU0.95 – 1.04 Ton3.37 – 3.66 kW
2.0 HP17,500 – 18,500 BTU1.45 – 1.54 Ton5.12 – 5.42 kW
2.5 HP20,500 – 22,500 BTU1.70 – 1.87 Ton6.00 – 6.59 kW
From HP to other units
Main Unit (Ton)Equivalent BTUEquivalent HPEquivalent kW
1.00 Ton12,000 BTU1.5 HP3.51 kW
1.50 Ton18,000 BTU2.0 HP5.27 kW
2.00 Ton24,000 BTU2.5 HP7.03 kW
2.50 Ton30,000 BTU3.0 HP8.79 kW
From Ton to other units
Main Unit (kW)Equivalent BTUEquivalent HPEquivalent Ton
2.50 kW8,530 BTU1.0 HP0.71 Ton
3.50 kW11,942 BTU1.5 HP0.99 Ton
5.00 kW17,060 BTU2.0 HP1.42 Ton
7.10 kW24,225 BTU2.5 HP2.01 Ton
From kW to other units

In Malaysia, we use all 4 units of measurements all the time and I find myself keep pressing on my calculator when I'm working on cooling capacity related work. So, what are they?

What is BTU in Air Conditioning?

BTU stands for British Thermal Unit. BTU is a measurement of heat energy. BTU is defined as the amount of heat required to raise the temperature of 1 lb of water by 1°F.

When using BTU to estimate the cooling capacity of an air conditioner, time must be factored in. For instance, one hour. In another word, how much heat energy needs to be released to reduce the temperature of 1 lb of water by 1°F in one hour?

Hence, BTU per hour or BTU/HR is the precise unit to use when referring to the cooling capacity of an air conditioner. However, most people use BTU or BTU/HR interchangeably when referring to the cooling capacity of an air conditioner.

In my opinion, BTU is the best measurement unit to use when comparing and calculating the cooling capacity required. BTU can be converted into both kW and Ton scientifically. Besides, BTU is the most commonly used measurement unit and thus, communication with other people is easier.

What is Ton in Air Conditioning?

Ton in air conditioning is an acronym for refrigeration ton (RT). Ton is not referring to weight when used to describe the cooling capacity of an air conditioner. Refrigeration ton is defined as the rate of heat transfer required to melt 1 ton of pure ice at 0°C in 24 hours. The ton of pure ice is referring to the weight of the ice.

Before people have modern air conditioners, they use ice to cool their houses and store their foods. Thus, refrigeration ton was used to measure the consumption of 1 ton of ice in one day. Nowadays, refrigeration ton is still preferred by many people and it is mostly used in commercial air conditioning systems.

I use refrigeration ton (RT) for a large cooling capacity because BTU will be too long. For example, a 400RT chiller is equivalent to 4,800,000 BTU. Also, people are more difficult to understand long numbers.

What is BTU AC | What does BTU mean?
What is BTU AC | What does BTU mean?

What is HP or Horsepower in Air Conditioning?

HP or horsepower is a unit of measurement of power. Power is the amount of work done over a certain period of time. Horsepower is most commonly used to describe the power of an engine.

Initially, horsepower in air conditioning was referring to the rotational power of the motor in an air conditioner whereas back then it was a fairly good estimation of the resulting cooling capacity of the air conditioner.

Nowadays, horsepower is no longer a correct indication of the cooling capacity of an air conditioner. However, some people still use horsepower to refer to the range of cooling capacity of an air conditioner.

I think horsepower (HP) is the best when referring to residential air conditioners. Most people use home air conditioners and they don't necessarily understand BTU and Ton. Furthermore, they are often confused the kW for cooling capacity with the kW for power consumption. Horsepower is the simplest way to call the size of their air conditioners.

Why 1.0 HP is Equivalent to a Range of BTU?

Back then, air conditioner manufacturers use the rotational horsepower of the compressor motor as the indication of the cooling capacity of their air conditioners. Nowadays, this method is not applicable because it does not account for the efficiency of each component inside an air conditioner.

For example, two air conditioners with the same compressor motor can result in one air conditioner having a higher cooling capacity than the other due to better controls. However, it doesn't mean that if the same 1HP air conditioner but one has 8,500 BTU and the other has 9,500 BTU, the former one has poor efficiency. We need to compare them using the coefficient of performance (COP).

Nowadays, people still use horsepower as the indication of air conditioner cooling capacity probably because it is easier for most people to understand. However, BTU or kW or both are always included in the specification of an air conditioner even though the horsepower is stated.

What is kW or Kilowatt in Air Conditioning?

kW or kilowatt in air conditioning refers to two metrics: a) cooling capacity and b) power consumption. Kilowatt used for the cooling capacity of an air conditioner is derived from the heat transfer equation as follow:

Using kilowatt as the unit of measurement for the cooling capacity of an air conditioner is a convenient indicator of the efficiency of the air conditioner as it is the same unit of measurement as the input electrical power. However, don't get confused with their unit of measurement as they are two very different metrics.

Whenever I calculate the efficiency of an air conditioner, I'll convert BTU to kW because the coefficient of performance (COP) is calculated by dividing the output by the input (cooling capacity/power consumption). In another word, it's kW/kW.

Relevant post: How to Read Air Conditioner Specifications (12 Specs!).

Preference of Measurement Units for Cooling Capacity around the World

The unit of measurement used for the cooling capacity of an air conditioner is based on the preferences and practices of people in a particular region.

Based on the data that I've gathered, it seems like most of the countries prefer to use BTU and Ton when indicating the cooling capacity of an air conditioner. Some countries prefer to use HP and a few countries used kW to refer to the cooling capacity of an air conditioner. Nevertheless, it doesn't matter which measurement units we used as long as we can understand it.

If you want to learn more about the basics of HVAC system, I recommend you read my HVAC Basics (eBook). It'll provide you with foundational knowledge that you need to get started on HVAC.


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Yu Chang Zhen

I enjoy working on air conditioners and ventilation fans because Malaysia is a very hot country.

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