Retirement Planning Calculator

The three steps

1. Inflate today's expense to the retirement date: Expense at retirement = current expense × (1 + inflation)^(years to retirement).
2. Size the corpus using a real return during retirement (return adjusted for inflation) over your post-retirement years.
3. Grow current savings to retirement, subtract from the corpus, and solve for the monthly investment that fills the gap.

Worked example

Age 30, retire at 60, live to 85, ₹50,000/month expenses, 6% inflation, 11% pre-retirement and 7% post-retirement returns, ₹5,00,000 saved. The corpus works out to roughly ₹8–9 crore, needing an investment of the order of ₹25,000–30,000 a month, rising if you delay.

Assumptions to revisit every year

• Inflation: use your personal expense inflation, which may exceed headline CPI.
• Returns: keep the post-retirement return conservative — the portfolio should be lower-risk by then.
• Expenses: some fall in retirement (commute, EMIs) while healthcare rises.
• Longevity: planning to 85–90 gives a safety margin.

This model assumes level real spending through retirement and no pension, rental or other income. Add those separately by reducing the expense figure.