Our experienced team brings over 35 years of industry experience, showcasing extensive knowledge and expertise.
When specifying an air conditioner, cold room, freezer, blast freezer or refrigeration system, one of the most important technical specifications is cooling capacity.
Cooling capacity is commonly expressed using different units, including:
AC Cooling Capacity Converter
Because manufacturers, contractors and customers may use different units, it is important to understand what each unit means and how they relate to one another.
For example, an HVAC system may be described as a 24,000 BTU/h air conditioner, while another manufacturer may describe a similar cooling capacity as approximately 7.03 kW or 2 TR.
However, BTU/h, kW and refrigeration ton are units of cooling capacity, while HP is primarily a measure of mechanical power and is often used in refrigeration to describe compressor motor size. Therefore, HP cannot be converted to cooling capacity accurately using one universal conversion factor.
Cooling capacity is the rate at which a refrigeration or air-conditioning system can remove heat from a space, product, process or environment.
A refrigeration system does not simply “produce cold.” Instead, it removes heat.
For a cold room, for example, the refrigeration system must remove heat entering the room from sources such as:
The total heat load determines the required refrigeration capacity.
The refrigeration system must have sufficient capacity to remove the calculated heat load while maintaining the required temperature.
BTU/h means British Thermal Units per hour.
BTU is a traditional unit of heat energy. When expressed as BTU/h, it describes a rate of heat transfer.
In HVAC and refrigeration, BTU/h is commonly used to specify cooling capacity.
For example:
| HVAC Capacity | Approximate Cooling Capacity |
|---|---|
| 9,000 BTU/h | 2.64 kW |
| 12,000 BTU/h | 3.52 kW |
| 18,000 BTU/h | 5.28 kW |
| 24,000 BTU/h | 7.03 kW |
| 36,000 BTU/h | 10.55 kW |
| 48,000 BTU/h | 14.07 kW |
| 60,000 BTU/h | 17.58 kW |
A commonly used conversion is:
1 kW of cooling ≈ 3,412 BTU/h
Therefore:
kW = BTU/h ÷ 3,412
and:
BTU/h = kW × 3,412
Suppose an air conditioner has a rated cooling capacity of:
24,000 BTU/h
Then:
24,000 ÷ 3,412 ≈ 7.03 kW
Therefore, a 24,000 BTU/h air conditioner has approximately 7.03 kW of cooling capacity.
The kilowatt (kW) is an SI unit of power.
In refrigeration and HVAC specifications, kW can be used to describe cooling capacity.
This should not be confused with the electrical power consumed by the equipment.
For example, a refrigeration system may have:
10 kW cooling capacity
while consuming:
3 kW electrical power
These are two different quantities.
The first describes how much heat the system can remove.
The second describes how much electrical power the equipment requires.
This distinction is particularly important when designing solar-powered refrigeration systems, generators, batteries and electrical distribution systems.
AC Cooling Capacity Converter
This is one of the most important concepts in HVAC and refrigeration.
If a refrigeration system is rated at 10 kW cooling capacity, this does not necessarily mean that it consumes 10 kW of electricity.
The relationship between cooling output and electrical input is influenced by the system’s efficiency.
For example:
Cooling capacity = 10 kW
Electrical input = 3 kW
The approximate coefficient of performance (COP) would be:
COP = Cooling Capacity ÷ Electrical Input
COP = 10 ÷ 3
COP ≈ 3.33
A higher COP generally means more cooling is produced for each unit of electrical energy consumed, although actual performance depends on operating conditions.
A refrigeration ton, commonly written as TR, is a traditional unit of refrigeration capacity.
It is not the same thing as a tonne of mass.
This distinction is extremely important in cold storage.
A refrigeration ton measures cooling capacity.
A metric tonne measures mass.
Therefore:
1 TR ≠ 1 tonne of product
A cold room storing 10 tonnes of chicken does not necessarily require a 10-ton refrigeration system.
The required refrigeration capacity must be calculated from the actual heat load.
The commonly used relationship is:
1 TR = 12,000 BTU/h
Using the BTU-to-kW relationship:
1 TR ≈ 3.517 kW of cooling
Therefore:
| Refrigeration Capacity | BTU/h | Approx. kW |
|---|---|---|
| 1 TR | 12,000 | 3.52 |
| 2 TR | 24,000 | 7.03 |
| 3 TR | 36,000 | 10.55 |
| 5 TR | 60,000 | 17.58 |
| 10 TR | 120,000 | 35.17 |
| 20 TR | 240,000 | 70.34 |
The refrigeration ton originated from the historical amount of heat associated with melting a ton of ice over a defined period.
Today, the term is simply used as a standardized measure of refrigeration capacity.
It should therefore not be interpreted as the physical weight of a refrigeration machine or the quantity of product that can be stored.
HP means horsepower.
Horsepower is fundamentally a unit of mechanical power, not cooling capacity.
In refrigeration, however, compressor sizes are frequently described using horsepower.
For example, a compressor may be marketed as:
This can create confusion because people sometimes assume that:
1 HP = a fixed amount of cooling capacity
That is not technically correct.
HP means horsepower.
In physics, horsepower is a unit of power, not directly a unit of cooling capacity.
One mechanical horsepower is approximately:
However, HVAC manufacturers and markets often use terms such as:
In this context, HP is commonly used as an approximate equipment-size designation rather than a precise measurement of cooling capacity.
This distinction is particularly important when comparing air-conditioning systems from different manufacturers.
It is tempting to assume:
1 HP air conditioner = a fixed number of BTU/h.
However, there is no universal engineering rule that makes this exact.
Two air conditioners both marketed as 1.5 HP may have different:
Consequently, when selecting HVAC equipment, the manufacturer’s rated cooling capacity in BTU/h or kW is more precise than relying on HP alone.
Instead of specifying only:
“Supply a 2 HP air conditioner.”
A more technically precise specification would state something such as:
Cooling capacity: approximately 24,000 BTU/h (7.0 kW), subject to specified rating conditions.
The actual equipment model and manufacturer’s data sheet should then be checked.
The following table provides approximate conversions.
| BTU/h | kW Cooling | Refrigeration Ton |
|---|---|---|
| 9,000 | 2.64 kW | 0.75 TR |
| 12,000 | 3.52 kW | 1 TR |
| 18,000 | 5.28 kW | 1.5 TR |
| 24,000 | 7.03 kW | 2 TR |
| 30,000 | 8.79 kW | 2.5 TR |
| 36,000 | 10.55 kW | 3 TR |
| 48,000 | 14.07 kW | 4 TR |
| 60,000 | 17.59 kW | 5 TR |
| 72,000 | 21.10 kW | 6 TR |
| 96,000 | 28.14 kW | 8 TR |
| 120,000 | 35.17 kW | 10 TR |
An HVAC system does not necessarily produce exactly the same cooling capacity under every condition.
Capacity can be affected by:
For example, an inverter air conditioner may operate at different capacities depending on its compressor speed and the thermal load.
Therefore, a capacity such as 24,000 BTU/h should be understood as a rated or nominal capacity, not necessarily a constant output under every operating condition.
Manufacturers normally provide technical data showing how an HVAC system performs under specified test or rating conditions.
For professional HVAC selection, engineers should therefore consider the manufacturer’s:
Rather than selecting equipment based only on a label such as “2 HP” or “3 HP.”
Suppose an air conditioner has a nominal capacity of:
36,000 BTU/h
36,000 ÷ 3,412
≈ 10.55 kW
36,000 ÷ 12,000
= 3 TR
Therefore:
36,000 BTU/h ≈ 10.55 kW ≈ 3 TR
This does not mean that the air conditioner consumes 10.55 kW of electricity.
Its actual electrical consumption must be obtained from the manufacturer’s electrical input specifications.
Suppose a commercial HVAC system has a capacity of:
5 TR
5 × 12,000
= 60,000 BTU/h
5 × 3.517
≈ 17.59 kW
Therefore:
5 TR ≈ 60,000 BTU/h ≈ 17.59 kW cooling capacity
Again, 17.59 kW is the approximate cooling output, not necessarily the electrical consumption.
kW = BTU/h ÷ 3,412
BTU/h = kW × 3,412
TR = BTU/h ÷ 12,000
BTU/h = TR × 12,000
kW = TR × 3.517
TR = kW ÷ 3.517
These formulas are useful for comparing HVAC equipment specifications presented using different units.
No.
This is a common misconception in the air-conditioning market.
HP and TR represent different concepts.
HP is a unit of power and is also commonly used as an HVAC equipment-size designation.
TR is a unit of refrigeration capacity.
Therefore, it is not technically correct to establish a universal:
1 HP = X TR
conversion for air-conditioning capacity.
If an HVAC supplier specifies equipment in HP, the actual manufacturer’s data sheet should be checked for the corresponding BTU/h or kW cooling capacity.
When preparing a professional HVAC quotation, tender, specification or engineering document, it is generally clearer to state the actual cooling capacity.
For example:
Cooling capacity: 24,000 BTU/h (7.03 kW, approximately 2 TR)
rather than simply:
2 HP air conditioner
The first specification gives considerably more useful engineering information.
The equipment model should also be included where precise equipment selection is required.
| Measurement | What It Represents | Direct Cooling Capacity? |
|---|---|---|
| BTU/h | Rate of heat removal | Yes |
| kW cooling | Rate of heat removal | Yes |
| TR | Refrigeration capacity | Yes |
| HP | Power / equipment designation | No, not directly |
BTU/h, kW and TR can be directly converted into one another because they express cooling capacity.
HP should be treated differently because it is not a direct universal measure of HVAC cooling capacity.