BTU (IT) per second to watts conversion calculator above calculates how many watts are in 'X' BTU (IT) per second (where 'X' is the number of BTU (IT) per second to convert to watts). In order to convert a value from BTU (IT) per second to watts (from BTU/s to W) type the number of BTU/s to be converted to W and then click on the 'convert' button.