BTU to Watts Calculator
Convert HVAC cooling or heating power from BTU/hr to electrical watts (W).
How to convert BTU to Watts
The formula is Watts = BTU/hr / 3.412142.
For example, a typical 12000 BTU/hr window air conditioner is equivalent to approximately 3517 W of thermal cooling power. This represents the heat removed, not necessarily the electrical draw.
Common BTU/hr to Watts Conversions
| BTU/hr | Watts (W) | Kilowatts (kW) |
|---|---|---|
| 5,000 BTU/hr | 1,465 W | 1.47 kW |
| 8,000 BTU/hr | 2,345 W | 2.35 kW |
| 12,000 BTU/hr | 3,517 W | 3.52 kW |
| 18,000 BTU/hr | 5,275 W | 5.28 kW |
| 24,000 BTU/hr | 7,034 W | 7.03 kW |
HVAC Cooling Capacity vs. Electrical Watts
In air conditioning, "BTU/hr" describes the thermal cooling capacity, while "Watts" describes the electrical power required to move that heat. The ratio between them is the unit's efficiency (EER/CEER). Here are typical figures for modern AC units:
| AC Unit Size | Cooling Capacity (Watts equivalent) | Typical Electrical Draw | Approx. CEER Efficiency |
|---|---|---|---|
| 5,000 BTU/hr (Small Window) | 1,465 W of heat removed | 450 - 500 W | 11.0 |
| 12,000 BTU/hr (1 Ton Mini-Split) | 3,516 W of heat removed | 900 - 1,100 W | 12.0 - 14.0 |
| 36,000 BTU/hr (3 Ton Central AC) | 10,550 W of heat removed | 2,800 - 3,300 W | 11.5 - 13.0 |
Notice that AC units pump significantly more heat energy (thermal watts) than they consume in electrical energy (electrical watts). A 12,000 BTU mini-split uses ~1,000W of electricity to move ~3,500W of heat outdoors.
Frequently Asked Questions
Is this the power my AC draws from the wall?
No. A 12,000 BTU/hr AC produces 3517 W of cooling power, but due to the refrigeration cycle (EER/SEER rating), it might only consume 1000 W to 1200 W of electrical power from your outlet.
What does BTU stand for?
British Thermal Unit. It is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.
What is the exact conversion factor?
One watt is equal to approximately 3.412142 BTU per hour.