Milliwatts to BTU (IT) per hour converter above calculates how many BTU (IT) per hour are in 'X' milliwatts (where 'X' is the number of milliwatts to convert to BTU (IT) per hour). In order to convert a value from milliwatts to BTU (IT) per hour (from mW to BTU/h) simply type the number of mW to be converted to BTU/h and then click on the 'convert' button.