How Do Companies Calculate Salaries with Varying Working Days Each Month?

I am working in an IT Company with a staff of approximately 50. Do companies follow a standard number of working days when calculating salary? Mostly, salaries are calculated based on the formula: (Monthly Gross * (number of days present / 26)). Generally, 26 working days are considered. But then, is it 26 working days for a 31-day month and 25 for a 30-day month? What about February? Also, what about national holidays? All your comments and suggestions will be highly appreciated.

Regards, Manidipa (HR Manager)

Normally, 26 days are used as a standard for calculating the wages per month. The Gratuity Act also considers 26 days as a base for calculating one day's wages.

Thank you.