Megajoules to British thermal units (IT) converter above calculates how many British thermal units (IT) are in 'X' megajoules (where 'X' is the number of megajoules to convert to British thermal units (IT)). In order to convert a value from megajoules to British thermal units (IT) (from MJ to BTU) simply type the number of MJ to be converted to BTU and then click on the 'convert' button.