The British Thermal Unit (BTU) is a traditional unit of energy commonly used in the United States, defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. In the International System of Units (SI), energy is measured in joules (J). The conversion between these units is precise: 1 BTU is equal to approximately 1,055.05585262 joules. To convert BTUs to joules, multiply the number of BTUs by this factor. Conversely, to convert joules to BTUs, divide the number of joules by 1,055.05585262. For example, 5 BTUs equal 5,275.2792631 joules, and 2,000 joules equal approximately 1.8956 BTUs. Understanding this conversion is essential in fields like heating, ventilation, and air conditioning (HVAC), as well as in energy consumption calculations. For quick conversions, online calculators are available to assist in accurately converting between BTUs and joules.