For calculation of EL under Factories Act, 1948 we are to go through chapter VIII of this Act but if the establishment is covered under the Bombay Shops Act then we are to grant EL as under:
An employee who has worked for not less than two hundred and forty days during a year irrespective of the date of commencement of his service, shall be allowed leave, consecutive or otherwise, for a period of not less than twenty-one days.
I hope that you are remembering 21 days leaves as per this shops act.