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Finance Formula

Retirement Formula

Published on July 05, 2026 • Last updated July 05, 2026

Mathematical Equation

$$\text{Target Corpus} = \text{Annual Expenses} \times \frac{1 - (1 + i)^{-n}}{i}$$

Variable Definitions

Target Corpus

Target Corpus

Total financial nest egg required at start of retirement

Annual Expenses

Annual Expenses

Estimated living expenses in the first year of retirement

i

i

Real rate of return (Expected Return - Inflation Rate)

n

n

Number of retirement years to plan for (life expectancy - retirement age)

Detailed Explanation

The retirement planning formula estimates the corpus required to sustain your current lifestyle during retirement. It accounts for inflation, which increases living costs, and calculates the necessary nest egg based on a real rate of return.

How to Calculate: Step-by-Step

1. Estimate your current annual living expenses. 2. Apply expected inflation rate to project expenses at the time of retirement. 3. Estimate life expectancy and retirement age to determine retirement years (n). 4. Calculate the real rate of return (i = (1 + R)/(1 + I) - 1, where R is return and I is inflation). 5. Compute the required target corpus.

Worked Calculation Example

If your projected annual expenses at retirement are INR 6,00,000, you plan for 25 years of retirement, and expect a real return of 2% (8% investment return minus 6% inflation): - Annual Expenses = INR 6,00,000 - Real Return (i) = 2% = 0.02 - Retirement Years (n) = 25 - Target Corpus = INR 11,713,934

Common Use Cases

  • Strategic retirement planning
  • Calculating required monthly savings to achieve target corpus

Frequently Asked Questions

The 4% rule suggests that if you withdraw 4% of your retirement corpus in the first year and adjust subsequent withdrawals for inflation, your savings should last at least 30 years.

Inflation erodes the purchasing power of money. A corpus that seems large today may buy much less in 20 or 30 years, which is why inflation must always be factored in.

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