SWP Goal — Reverse-Engineering Your Retirement Corpus
This solves the inverse SWP problem: given a target monthly income and horizon, what lump sum do you need today? The present-value annuity formula is PV = W · [1 − (1+i)⁻ⁿ] / i, with monthly compounding.
Stress-test the result against inflation: a flat-rupee withdrawal loses ~50% of its purchasing power over 12 years at 6% inflation. For a real-income target, escalate withdrawals annually or oversize the corpus by 25–40%.