How to Convert BTUs to Watts (and vice versa)
When comparing air conditioners, space heaters, or evaluating energy consumption, you will often need to convert between BTUs (British Thermal Units) per hour and Watts (W). Understanding this conversion is straightforward with the core formula:
1 Watt = 3.41214 BTUs per hour
1 BTU/hr ≈ 0.29307 Watts
To convert BTUs to Watts, multiply the BTUs by 0.293071 (or divide by 3.41214).
Example: A 10,000 BTU/hr air conditioner provides about 2,931 Watts of cooling power.
To convert Watts to BTUs, multiply the Watts by 3.41214.
Example: A 1,500W electric space heater produces approximately 5,118 BTUs of heat per hour (1,500 × 3.412).
Quick Conversion Chart
Here is a handy reference chart for common BTU and Watt values found in typical HVAC and heating equipment:
| BTUs per Hour (BTU/hr) | Power in Watts (W) | Power in Kilowatts (kW) |
|---|---|---|
| 5,000 BTUs | 1,465 W | 1.47 kW |
| 8,000 BTUs | 2,345 W | 2.34 kW |
| 10,000 BTUs | 2,931 W | 2.93 kW |
| 12,000 BTUs (1 Ton) | 3,517 W | 3.52 kW |
| 18,000 BTUs (1.5 Tons) | 5,275 W | 5.28 kW |
| 24,000 BTUs (2 Tons) | 7,034 W | 7.03 kW |
*Note: These conversions are for the cooling or heating capacity, not necessarily the electrical power consumed by the unit (which depends on the unit's efficiency/SEER/EER rating).
Frequently Asked Questions
What is the difference between BTUs and Watts?
BTU (British Thermal Unit) is traditionally used to measure heat energy, while Watt is a unit of power in the International System of Units (SI). In HVAC, 'BTU' usually refers to 'BTUs per hour' (a rate of energy transfer), which directly correlates to Watts. 1 Watt is equal to approximately 3.412 BTUs per hour.
How many Watts are in a BTU?
1 BTU per hour is equivalent to approximately 0.293071 Watts. So, a 10,000 BTU/hr air conditioner has a cooling capacity equivalent to about 2,930 Watts.
Why do some appliances use BTUs and others use Watts?
It mostly comes down to regional conventions and the type of appliance. Heating and cooling equipment (like ACs, furnaces, and gas heaters) often use BTUs in North America. Electrical devices (like electric space heaters or light bulbs) typically use Watts because they measure electrical power consumption directly.