Liter-atmosphere to megacalories conversion calculator shown above calculates how many megacalories are in 'X' liter-atmosphere (where 'X' is the number of liter-atmosphere to convert to megacalories). In order to convert a value from liter-atmosphere to megacalories (from L atm to Mcal) type the number of L atm to be converted to Mcal and then click on the 'convert' button.