Watt hours to British thermal units (IT) conversion calculator shown above calculates how many British thermal units (IT) are in 'X' watt hours (where 'X' is the number of watt hours to convert to British thermal units (IT)). In order to convert a value from watt hours to British thermal units (IT) (from Wh to BTU) just type the number of Wh to be converted to BTU and then click on the 'convert' button.