In HVAC, power is commonly measured in two units: Watts and British Thermal Units per hour (BTU/hr).
In the realm of HVAC, Power is often expressed in two different units:
 Watts (W)
 BTUs per hour (BTU/h)
HVAC Power Units: Watts and BTUs per Hour (BTU/h)
Unit  Description 
British Thermal Unit (BTU) 

Watts 

Stating that BTUs can be directly converted into watts is somewhat misleading since BTUs represent energy, while watts measure the rate of energy transfer.
When discussing the conversion of BTUs into watts, what is actually meant is the conversion of BTUs per hour (BTU/h) into watts.
If you have the wattage or BTU/h value needed to heat or cool your space, you can easily calculate using a simple formula / convert them into your preferred unit of measurement.
How to convert BTU/h to Watts?
The conversion formula between these two units of power can be represented as follows:
or
The following table addresses the most frequently asked questions about converting BTUs to Watts and Kilowatts:
BTU  Watts  Kilowatts 
How many Watts does 5,000 BTU Air Conditioner use?  1465  1.465 
How many Watts does 6,000 BTU Air Conditioner use?  1758  1.758 
How many Watts does 7,000 BTU Air Conditioner use?  2051  2.051 
How many Watts does 8,000 BTU Air Conditioner use?  2344  2.344 
How many Watts does 9,000 BTU Air Conditioner use?  2637  2.637 
How many Watts does 10,000 BTU Air Conditioner use?  2930  2.930 
How many Watts does 11,000 BTU Air Conditioner use?  3223  3.223 
How many Watts does 12,000 BTU Air Conditioner use?  3516  3.516 
How many Watts does 13,000 BTU Air Conditioner use?  3809  3.809 
How many Watts does 14,000 BTU Air Conditioner use?  4102  4.102 
How many Watts does 15,000 BTU Air Conditioner use?  4395  4.395 
How many Watts does 16,000 BTU Air Conditioner use?  4688  4.688 
How many Watts does 17,000 BTU Air Conditioner use?  4981  4.981 
How many Watts does 18,000 BTU Air Conditioner use?  5274  5.274 
How many Watts does 19,000 BTU Air Conditioner use?  5567  5.567 
How many Watts does 20,000 BTU Air Conditioner use?  5860  5.860 
How many Watts does 21,000 BTU Air Conditioner use?  6153  6.153 
How many Watts does 22,000 BTU Air Conditioner use?  6446  6.446 
How many Watts does 23,000 BTU Air Conditioner use?  6739  6.739 
How many Watts does 24,000 BTU Air Conditioner use?  7032  7.032 
To get the most accurate calculation though, refer to the manufacturer’s specifications or label to find the exact EER rating.
How to convert Watts to BTU/h?
Conversely, if you want to do the conversion from Watts to BTU/h, use these formulas:
or
Ensuring precision in air conditioner energy consumption measurement
In reality though, the actual amount of Watts depends on the thermostat setting and the ambient temperature, the insulation, ceiling height, number of people in the room, how many hours it operates a day, and of course, upon the size and age of the unit, on the EER rating, or its efficiency, and other factors.
For the most accurate figures, it is advisable to test the actual values using a Watthour meter or kW/h meter.
Watt meters, such as the Poniie PN2000 Plugin kilowatt electricity usage monitor are plugged into the power socket and then your air conditioner is plugged into the watt meter.
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The meter will then provide a digital readout, indicating the kilowatts consumed by your air conditioning unit per hour.