Retirement Corpus Calculator

How to Calculate Your Retirement Corpus

A retirement corpus is the pool of money you need at retirement so that your future expenses can be funded without regular salary income. The first step is to estimate your current monthly expenses. Then calculate how much those expenses may become by the time you retire. This page compounds your current monthly expenses by the expected inflation rate for the number of years left until retirement.

After that, the calculator estimates the corpus required at retirement. It assumes your retirement expenses continue to rise with inflation each year, while your post-retirement investments earn the return rate you enter. The corpus is calculated by discounting each year of future inflated expenses back to your retirement year. This is more realistic than simply multiplying expenses by the number of retirement years because it considers both investment returns and inflation.

The Impact of Inflation on Retirement

Inflation is one of the biggest risks in retirement planning. A monthly expense of ₹50,000 today can become much larger after 25 or 30 years. At 6% annual inflation, prices roughly double every 12 years. That means rent, groceries, healthcare, travel and lifestyle costs can look very different when you retire. Planning only with today’s expenses can lead to under-saving.

For India, inflation planning is especially important because healthcare and urban living costs may rise faster than broad averages. A good retirement plan should stress-test different inflation assumptions and not rely on one perfect number.

The 4% Withdrawal Rule Explained

The 4% withdrawal rule is a popular retirement rule of thumb. It says a retiree may withdraw about 4% of the starting retirement corpus in the first year, then adjust withdrawals for inflation each year. It became famous from research on historical retirement portfolios, especially work associated with William Bengen and the Trinity Study. However, it is not a guarantee.

The rule was based on assumptions about portfolio mix, historical returns and retirement duration. If you retire early, expect a 40-year retirement, hold very conservative investments, or face high inflation, a 4% withdrawal rate may be too aggressive. For Indian investors, taxes, debt-equity mix, rupee inflation and healthcare costs should also be considered. Use the 4% rule as a starting idea, not a final plan.

Real Example

Amit is 28 and plans to retire at 60, giving him 32 years to prepare. His household needs ₹50,000 a month in today’s money, and he expects to plan until age 85, or 25 retirement years. Using 6% annual inflation, the calculator first increases today’s ₹50,000 monthly expense for 32 years: ₹50,000 × 1.06³² is about ₹1.32 lakh per month at retirement. His first retirement-year expense is therefore about ₹15.5 lakh. If Amit assumes his retirement portfolio earns 8% annually while expenses keep rising 6%, the calculator discounts each of those 25 years of future spending back to his retirement date. This produces a required corpus of roughly ₹7.3 crore. The calculation is not a promise: taxes, medical costs, investment returns, and lifestyle changes can move the answer. Amit can turn it into an action plan by reviewing how much he already has invested, estimating the SIP needed to close the gap over 32 years, increasing contributions after salary hikes, and keeping a separate health and emergency buffer. Re-running the calculator each year will help him adjust before retirement is close.

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