1. Retirement Planner
You can use this to find out how much corpus you will need to retire.
2. Advanced Savings Calculator
I understand that your monthly savings are not constant for the next n years. You might increase your savings on a yearly basis. You can add that input here as well.
3. Reverse Savings
You input the goal and the number of years you have achieve it, this will tell you how much you need to start saving every month from now.
Note: Read the notes in each of the page to understand how the calculator works and the factors that are taken into account.