Willian's line follows the law (where b = A constant representing the shape of the Willian's line, a = Another constant i.e. no load consumption per hour, I.P. = Indicated power, and m = Steam consumption per hour)

• I.P. = a x m + b
• m = a + b x I.P.
• I.P. = b x m + a
• m = b/I.P. - a