Two numbers, one comparison
The projected corpus from steady saving (₹10,00,000 already saved, ₹10,000/month, 10% return, 30 years to retirement) is ₹4,02,42,655.51. The corpus actually needed to sustain a ₹50,000-a-month lifestyle through a 25-year retirement, adjusted for inflation, is ₹5,71,11,047.49. The gap between them: ₹1,68,68,391.98.
Turning the gap into an additional monthly SIP
Feeding that exact ₹1,68,68,391.98 gap into a SIP goal calculation — at the same 10% expected return, over the same 25 years — gives a required additional monthly SIP of ₹12,608.20. Investing that much more each month, on top of the original ₹10,000, would be projected to close the entire shortfall by retirement.
Why this three-step chain matters
Each calculator alone gives an incomplete picture: a projection alone doesn't say whether the result is enough, and a corpus target alone doesn't say how to get there from where someone actually is. Chaining all three — project, size the real target, then solve for the gap — turns two separate numbers into one concrete action: increase the SIP by a specific, calculated amount.
What could change this result
A higher expected return, a longer time horizon, or a lower target expense in retirement would all reduce the required additional SIP — this chain can be re-run with any of those adjusted to see how sensitive the shortfall is to each assumption.