BTU / Kilowatt Converter

The BTU / Kilowatt Converter converts between British Thermal Units per hour (BTU/hr) and kilowatts (kW), the two most common units for expressing heating and cooling power in HVAC and refrigeration engineering. It also converts to tons of refrigeration, a widely used US rating for air conditioning and chiller capacity.

The BTU (British Thermal Unit) is defined as the amount of heat required to raise one pound of water by one degree Fahrenheit. As a power unit, BTU/hr describes the rate of heat transfer. The kilowatt, the SI unit of power, represents 1000 joules per second. The conversion factor is: 1 kW = 3412.142 BTU/hr, or equivalently 1 BTU/hr = 0.000293 kW.

The ton of refrigeration is an American unit defined as the heat extraction rate needed to freeze one short ton (2000 lbs) of water at 32°F in 24 hours. This equals 288,000 BTU/day = 12,000 BTU/hr = 3.517 kW. HVAC equipment in the US is commonly rated in tons: a '5-ton AC' has 60,000 BTU/hr = 17.58 kW of cooling capacity.

These conversions are used constantly in: HVAC load calculations (Manual J for residential, ASHRAE loads for commercial), chiller and cooling tower selection, data center thermal management, industrial process cooling, and heat pump sizing. Understanding the relationship between BTU/hr and kW allows engineers and contractors to compare equipment rated in different unit systems.

In electrical terms, 1 kW of electrical power consumed by a resistive heater produces exactly 3412 BTU/hr of heat. This is the basis for comparing electric resistance heating to heat pumps — a heat pump with COP 3.5 produces 3.5 × 3412 = 11,942 BTU/hr of heat per kW of electricity, compared to 3412 BTU/hr for resistance heating. Heat pumps are thus 3.5× more efficient at converting electricity to heat.