Calories (15 °C) to watt hours conversion calculator above calculates how many watt hours are in 'X' calories (15 °C) (where 'X' is the number of calories (15 °C) to convert to watt hours). In order to convert a value from calories (15 °C) to watt hours (from cal to Wh) just type the number of cal to be converted to Wh and then click on the 'convert' button.