Hi, @Annonymous
You may find many Excel formats regarding the Salary Calculation on this Website.
It's very important to understand the salary structure as per your state govt. Laws.
Generally, there will be following components.
Basic, DA (Dearness Allowance), HRA (House rent Allowance), Medical Allowance, Children Education Allowance, LTA (Leave Travel Allowance), Conveyance Allowance, Etc.
Please note concept of salary structure
Basic + allowances = Gross Salary (ESIC & PT will be calculated on Gross Salary)
Gross Salary + Employee's Contribution to PF & ESIC = CTC.
Now, Answer of your Question. (Example 20 k Salary)
Basic (10000) + other allowances = Gross Salary
Gross + PF + ESIC + PT = CTC
Hope this will help to understand & design your own salary structure.