The 50/30/20 rule splits take-home pay into 50% needs, 30% wants and 20% savings. On ₹30,000 that is ₹15,000 for needs such as rent, groceries, transport and EMIs, ₹9,000 for wants such as eating out and shopping, and ₹6,000 for savings.
That leaves about ₹800 a day of spending room once savings are moved out on payday. Use take-home pay, not CTC, since the split only works on money that reaches your account.
The rule is a starting point. In an expensive city on a lower salary, needs can run well past 50%, and forcing 20% into savings means borrowing by the 25th. In that case, save what you can keep and raise it with each increment.
There is a table for every salary from ₹8,000 to ₹2,00,000 in the guide to budgeting your salary in India with the 50/30/20 plan.