Retirement Corpus Calculator
Find the corpus you actually need to retire — adjusted for inflation eating into your future expenses — and see whether your current savings and SIP are already on track.
How retirement numbers add up
Today's expense isn't tomorrow's
At 6% inflation, a ₹50,000 monthly expense today becomes roughly ₹1,60,000 in 20 years — your retirement corpus has to fund that larger number, not today's.
Growing vs preserving capital
Pre-retirement, you can usually afford more equity exposure for higher growth. Post-retirement, capital preservation usually matters more, which is why this calculator uses two separate return assumptions.
Small increases now, large effect later
If there's a shortfall, the additional monthly SIP needed to close it gets larger the longer you wait — closing even part of the gap today is easier than catching up in your 50s.
- 01What is a retirement corpus, and why a number matters
- 02Why inflation changes the entire calculation
- 03How the required corpus is actually calculated
- 04A worked example, step by step
- 05Closing a shortfall: the earlier, the easier
- 06Why this calculator uses two different return rates
- 07Common retirement planning mistakes to avoid
- 08How to use this calculator
What is a retirement corpus, and why a number matters
Your retirement corpus is the total invested sum you need to have accumulated by the day you retire, large enough that it can fund your living expenses for the rest of your life without running out. "Save as much as possible" is well-meaning advice but not actionable — a specific target number, even an estimate, is what lets you check whether you're actually on track today, years before retirement, while there's still time to adjust.
This calculator combines four things that are each individually well-understood, but rarely modelled together correctly: inflation eating into your future expenses, the corpus's own growth before retirement, the corpus's growth (and depletion) during retirement, and the gap-closing contribution needed if your current trajectory falls short.
Why inflation changes the entire calculation
The most common and most damaging mistake in retirement planning is sizing the corpus around today's monthly expenses, ignoring that those expenses will be considerably higher by the time retirement actually arrives, and will keep rising throughout retirement itself.
At 6% annual inflation, a ₹50,000 monthly expense today becomes roughly ₹2,87,000 per month in 30 years — not because your lifestyle changed, but purely because prices rose. A retirement plan built around today's ₹50,000 figure would fall dramatically short.
How the required corpus is actually calculated
This calculator works through four sequential steps:
- Inflate today's expense forward to the year you actually retire: Expense at Retirement = Current Expense × (1 + inflation)years to retirement.
- Size the corpus as a real-rate annuity that needs to fund this inflating expense stream for your full expected retirement duration, discounted at your post-retirement return rate net of ongoing inflation (since expenses keep rising even after you've retired).
- Project your current trajectory — what your existing savings and ongoing SIP are on track to become by retirement, using the same compounding formulas as the Lumpsum and SIP calculators.
- Compare the two — if your projected corpus falls short of the required corpus, solve for the additional monthly SIP needed to close that specific gap.
A worked example, step by step
A 30-year-old planning to retire at 60, expecting to live to 85, currently spending ₹50,000/month, assuming 6% inflation, a 12% pre-retirement return, and a 7% post-retirement return, with ₹10,00,000 already saved and a current ₹20,000/month SIP.
| Metric | Value |
|---|---|
| Years to retirement | 30 |
| Years in retirement | 25 |
| Monthly expense at retirement (inflated) | ₹2,87,175 |
| Required corpus at retirement | ₹7,67,57,369 |
| Projected corpus (savings + SIP) | ₹10,05,58,198 |
| Result | Surplus of ₹2,38,00,829 |
In this example, the current savings and SIP trajectory comfortably exceeds the inflation-adjusted target — but change the monthly SIP to a more modest ₹5,000 and the same plan can flip to a substantial shortfall, illustrating how sensitive the outcome is to the actual monthly contribution.
Closing a shortfall: the earlier, the easier
When projected corpus falls short of the required corpus, this calculator runs the shortfall through the same reverse-SIP solver used by the Goal Planning Calculator, showing the additional monthly investment needed to close the gap by retirement. The further away retirement is, the smaller this additional amount needs to be — a gap that requires a large top-up SIP at age 50 might have required only a modest one if identified and addressed at age 30, purely because compounding had three fewer decades to work in the later scenario.
Why this calculator uses two different return rates
Pre-retirement and post-retirement portfolios typically serve different purposes and carry different risk tolerances. Before retirement, with years or decades for volatility to smooth out, a higher equity allocation and higher expected return (commonly modelled at 10–12%) is standard. After retirement, capital preservation and stable income usually matter more than growth, leading to a more conservative allocation and lower expected return (commonly modelled at 6–8%). This calculator lets you set both rates independently to reflect that shift.
Common retirement planning mistakes to avoid
- Ignoring inflation entirely. Sizing a corpus around today's expenses, without inflating them forward to the retirement date and throughout retirement, is the single most common and most damaging error.
- Using the same return assumption before and after retirement. Most financial plans should shift to a more conservative allocation (and lower expected return) after retirement begins.
- Underestimating life expectancy. Planning for a 20-year retirement when you may well live 30+ years risks a corpus that runs out with years of expenses still ahead.
- Treating the result as fixed and final. Inflation, market returns, and your own circumstances will all drift from any single set of assumptions — revisit this calculation every year or two, adjusting contributions as needed.
How to use this calculator
- Enter your current age, planned retirement age, and expected life expectancy.
- Enter your current monthly expense and an inflation assumption (6% is a commonly used long-term planning figure for India).
- Set separate pre-retirement and post-retirement return assumptions.
- Enter your current savings and ongoing monthly SIP.
- Read the required corpus, your projected corpus, and if there's a shortfall, the additional monthly SIP needed to close it.
Frequently asked questions
Because the calculation accounts for two compounding effects most rough estimates miss: your monthly expense itself grows with inflation throughout retirement (not just up to the retirement date), and the corpus needs to keep generating returns to sustain an inflating expense stream for potentially 20-30+ years, not just cover a fixed multiple of today's expense.
6% is a commonly used long-term planning assumption for India, broadly consistent with historical CPI inflation over multi-decade periods, though actual year-to-year inflation varies considerably. Using a higher figure produces a more conservative (larger) required corpus; a lower figure produces a smaller one - when in doubt, erring toward a slightly higher assumption is the safer planning choice.
Because the appropriate investment allocation typically changes at retirement. Before retirement, with years for volatility to smooth out, a higher-growth, more equity-heavy allocation is standard. After retirement, when you're actively drawing down the corpus, capital preservation and income stability usually matter more, leading most financial plans to shift toward a more conservative, lower-return allocation.
The calculator will show a larger required additional monthly SIP, reflecting the reduced time available for compounding to work. This is exactly the scenario where starting now, even with imperfect numbers, beats waiting longer - the gap-closing contribution only grows as retirement approaches.
No. This calculator models your corpus from current savings and SIP contributions alone. If you have EPF, NPS, a defined pension, or other guaranteed income streams, you should treat the required corpus shown here as the portion needed beyond those sources, not the total - reduce your effective monthly expense input accordingly, or treat any pension as reducing the corpus you personally need to build.
At least once a year, or whenever your income, savings rate, or major life circumstances change meaningfully. Retirement planning is not a calculation you do once and forget - revisiting it periodically lets you catch and correct a drifting shortfall while there's still time for compounding to help close it.