Therms to BTU Converter

The Therms to BTU Converter converts energy from therms to British Thermal Units (BTU), megajoules (MJ), and kilowatt-hours (kWh) using the exact definition 1 therm = 100,000 BTU. The therm is a standard unit for measuring natural gas consumption in the United States and is fundamental to energy billing and HVAC engineering.

Natural gas utilities in the US typically bill customers in therms. One therm represents the energy content of approximately 100 cubic feet (CCF) of natural gas, though the exact energy content varies slightly with gas composition. Understanding how therms relate to other energy units is essential for comparing fuel costs, evaluating heating system efficiency, and performing building energy analysis.

The therm was legally defined by the EC Directive 80/181/EEC as exactly 100,000 BTU_IT. Using the International Table BTU value of 1,055.05585262 J, one therm equals approximately 105,505,585 J ≈ 105.506 MJ. In electrical terms, one therm equals about 29.3 kWh, which provides a direct comparison between gas and electric heating costs.

For home energy analysis, knowing the therm-to-kWh conversion is particularly valuable. If natural gas costs $1.00 per therm and electricity costs $0.12 per kWh, then gas heating costs about $1.00 per 29.3 kWh while electric heating costs about $3.52 for the same energy (29.3 × $0.12). This explains why gas heating is typically cheaper per unit of energy, though heat pump efficiency can change the equation.

Our converter provides three output units — BTU for HVAC applications, megajoules for international engineering standards, and kilowatt-hours for electrical energy comparison — making it versatile for energy analysis across disciplines.