Watt seconds to megawatt hours conversion calculator above calculates how many megawatt hours are in 'X' watt seconds (where 'X' is the number of watt seconds to convert to megawatt hours). In order to convert a value from watt seconds to megawatt hours (from Ws to MWh) simply type the number of Ws to be converted to MWh and then click on the 'convert' button.