Watts to BTU Calculator
Convert electrical heating or cooling power from watts (W) to BTU/hr.
How to convert Watts to BTU/hr
The formula is BTU/hr = Watts × 3.412142.
For example, a 1500 W space heater will output approximately 5118 BTU/hr. Resistive electric heating is 100% efficient, so the electrical watts equal the thermal watts output.
Common Watts to BTU/hr Conversions
| Watts (W) | BTU/hr |
|---|---|
| 100 W | 341 BTU/hr |
| 500 W | 1,706 BTU/hr |
| 1,000 W | 3,412 BTU/hr |
| 1,500 W | 5,118 BTU/hr |
| 2,000 W | 6,824 BTU/hr |
Calculating Heat Loads for IT and Server Rooms
In the world of thermodynamics, all electrical energy consumed by a device inside a room eventually turns into heat. HVAC engineers convert the electrical Watts consumed by computers into BTU/hr to size the air conditioning correctly.
- Standard Desktop PC & Monitors (300 W continuous):
BTU/hr = 300 × 3.412 = 1,023 BTU/hr. One person working at a desk adds about 400 BTU/hr of body heat, so the PC generates more than twice the heat of the human operator. - Small Server Rack (3,000 W):
BTU/hr = 3,000 × 3.412 = 10,236 BTU/hr. This single rack requires almost a full "ton" (12,000 BTU/hr) of dedicated air conditioning cooling capacity just to remain at room temperature. - 1,500 W Electric Space Heater:
BTU/hr = 1,500 × 3.412 = 5,118 BTU/hr. This is exactly why a 1,500W space heater outputs the same amount of heat as a dedicated 5,000 BTU gas heater.
Frequently Asked Questions
Why convert watts to BTU?
BTU is the standard measurement for HVAC systems in the United States, so converting electrical power to BTU helps you size a space heater or understand the cooling equivalent of your equipment.
Are all watts converted to heat?
For a purely resistive electric heater, yes, essentially 100% of the electrical watts are converted to heat (thermal watts), which equals 3.412 BTU/hr per watt.
Is a BTU the same as a ton of AC?
No, but they measure the same thing. One "ton" of refrigeration capacity is equal to 12,000 BTU/hr.