BTU to Watts Converter: Complete Guide to Converting BTU/hr to Watts
BTU (British Thermal Unit) and watts are the two dominant units for measuring heating and cooling power worldwide. HVAC equipment in the United States is rated in BTU/hr while European and international specifications use watts or kilowatts. A 12,000 BTU/hr air conditioner — the ubiquitous "1-ton" unit — equals 3,516.85 watts (3.52 kW). Understanding this conversion is essential for electrical planning, energy billing, equipment comparison, and international product compatibility.
The Exact Relationship: 1 BTU/hr = 0.29307 Watts
One BTU per hour equals exactly 0.29307107017 watts. This conversion derives from the BTU itself: 1 BTU = 1055.06 joules, and 1 watt = 1 joule/second. Since BTU/hr measures joules per hour: 1055.06 ÷ 3600 seconds = 0.29307 W. The formula is: W = BTU/hr × 0.29307.
1 watt = 3.41214 BTU/hr
Formula: W = BTU/hr × 0.29307
kW = BTU/hr × 0.00029307
Common references:
5,000 BTU/hr = 1,465 W (small window AC)
12,000 BTU/hr = 3,517 W (1 ton AC)
24,000 BTU/hr = 7,034 W (2 ton AC)
36,000 BTU/hr = 10,551 W (3 ton AC)
48,000 BTU/hr = 14,068 W (4 ton AC)
Air Conditioning and HVAC
Air conditioner capacity is rated in BTU/hr in the US, but electrical consumption is measured in watts. A 12,000 BTU/hr window AC draws approximately 900–1,200 watts electrically — the BTU/hr figure describes cooling capacity, not power consumption. However, BTU/hr and watts describe the same physical quantity (power), so the conversion is exact. A 1-ton AC = 12,000 BTU/hr = 3,516.85 watts of cooling capacity. For mini-split systems marketed in kW internationally: a 3.5 kW unit = 3,500 W = 11,945 BTU/hr ≈ 12,000 BTU/hr (1 ton).
Heating Systems
Gas furnaces, boilers, and electric heaters all intersect the BTU/watt boundary. A 60,000 BTU/hr gas furnace = 17,584 watts = 17.58 kW of heat output. Electric baseboard heaters are sold in watts: a 2,000 W heater = 6,824 BTU/hr. Infrared heaters: a 1,500 W unit = 5,118 BTU/hr. Boilers for European homes are rated in kW; US equivalents in BTU/hr. A 30 kW boiler = 102,364 BTU/hr — knowing this lets you compare systems across markets.
Electrical Planning
When installing HVAC equipment, the electrical circuit must handle the actual wattage. A 24,000 BTU/hr unit = 7,034 watts of cooling capacity. The EER (Energy Efficiency Ratio) gives actual watt consumption: EER = BTU/hr ÷ watts. A 24,000 BTU unit with EER 12 consumes 24,000 ÷ 12 = 2,000 watts of electricity. This calculation requires the BTU-to-watt conversion at every step.
How to Use This Converter
Enter any BTU/hr value to see watts instantly. Quick buttons cover common AC sizes from 5,000 to 60,000 BTU/hr. The flame visualizer animates heat intensity. The power meter shows the equivalent wattage on a radial gauge. The AC context panel compares your value against 4 standard unit sizes. All units display simultaneously: watts, kilowatts, AC tons, kcal/hr, and horsepower.