Tip: BTU (without “per hour”) is energy. HVAC sizing usually uses BTU/h, which converts directly to watts.
BTU to Watts Conversion Guide
If you are comparing heaters, air conditioners, heat pumps, or any HVAC equipment, you will often see two power ratings: BTU/h and watts. This calculator helps you convert between them instantly so you can compare products correctly.
What is BTU/h?
BTU stands for British Thermal Unit. One BTU is the amount of heat needed to raise one pound of water by one degree Fahrenheit. In appliance ratings, manufacturers usually use BTU per hour (BTU/h), which represents a rate of heating or cooling power.
What is a watt?
A watt (W) is the SI unit of power. It tells you how quickly energy is transferred or used. Electrical devices are commonly rated in watts or kilowatts (kW).
Conversion Formula
Watts = BTU/h × 0.29307107
BTU/h = Watts × 3.412141633
These are reciprocal formulas. You can convert in either direction using the same physical relationship between imperial and metric power units.
Quick Reference Values
- 1,000 BTU/h ≈ 293.07 W
- 5,000 BTU/h ≈ 1,465.36 W
- 9,000 BTU/h ≈ 2,637.64 W
- 12,000 BTU/h ≈ 3,516.85 W
- 18,000 BTU/h ≈ 5,275.28 W
- 24,000 BTU/h ≈ 7,033.71 W
How to Use This Calculator
- Enter a number in BTU/h to convert to watts, then click Convert BTU/h → Watts.
- Enter a number in Watts to convert to BTU/h, then click Convert Watts → BTU/h.
- Use Clear to reset both fields and start over.
Common Use Cases
1) Sizing an air conditioner
Window and mini-split AC systems are often labeled in BTU/h (for example, 12,000 BTU/h). If you want to estimate electrical power in watts, this conversion gives a direct unit comparison. Keep in mind: actual electrical input depends on efficiency (EER/SEER/COP), not only cooling capacity.
2) Comparing electric heaters
Space heaters are usually listed in watts. Converting to BTU/h can help compare heating output with HVAC specs or building load calculations.
3) Generator and inverter planning
If an appliance is rated in BTU/h and your backup power system is rated in watts, conversion helps you estimate required output before purchase.
Important Notes
- Do not confuse BTU (energy) with BTU/h (power).
- This calculator converts ideal unit values. Real appliance consumption may vary by duty cycle and efficiency.
- For total energy cost, also consider runtime (hours) and electricity price per kWh.
FAQ
Is 1 watt equal to 3.41 BTU?
More precisely, 1 watt = 3.412141633 BTU/h. Rounding to 3.41 is common for quick estimates.
How many watts is 12,000 BTU?
12,000 BTU/h is approximately 3,516.85 watts.
Can I use this for both heating and cooling?
Yes. BTU/h and watts are both power units, so the same conversion works for heating and cooling capacity.