Two growth streams, added together
For someone aged 30 with ₹10,00,000 already saved, contributing ₹10,000 a month, expecting a 10% annual return, retiring at 60: the existing ₹10,00,000 compounds on its own to ₹1,74,94,022.27 by retirement, while the ongoing ₹10,000 monthly contributions grow to ₹2,27,93,253.24. Added together, the projected total corpus is ₹4,02,42,655.51.
Why the contributions grow to more than the starting savings
Even though the total amount actually contributed over 30 years (₹46,00,000, including the original ₹10,00,000) is far less than either growth figure alone, monthly contributions made every month for three decades — even the ones added in the final few years — collectively outgrow a single lump sum that only had less time in some ways but more compounding room in others. Both streams benefit from the same 10% return, just applied differently.
What this projection assumes
This assumes a constant 10% annual return for the full 30 years and a constant ₹10,000 monthly contribution — real returns fluctuate, and many people increase their contributions as income grows over a career.
What this projection doesn't answer
This shows what corpus you're on track to reach — it says nothing about whether that corpus is actually enough to retire comfortably. That's a different, backward-looking question, covered in the companion article on calculating the corpus you actually need.