Retirement Planning — The Mathematics of Financial Freedom
The corpus needed at retirement is the present value of an inflation-adjusted annuity that funds your expected lifestyle for the remainder of life. The model uses the real rate of return post-retirement to neutralise inflation drag on withdrawals.
Formula
Future monthly expense: E × (1+i)ᵗ. Corpus: PV annuity at real rate (1+r)/(1+i) − 1. Required SIP back-solved from FV-of-annuity-due formula.