There is no formula to calculate this amount. The basic salary is generally around 40% to 50% of your total salary.
It is a part of the Cost to Company (CTC) that the employers pay to the employees for their services. Below is a list of the most common breakdown of the salary structure. The salary has many components that may vary among different employers. The amount they receive is usually mentioned in their contract as well as the pay slip.
In every professional field, employees get paid at the end of the month by their employers.