What is a retirement Calculator?
Retirement planning has two moving targets at once: your expenses will be higher by the time you retire (inflation), and that inflated expense needs to be funded for decades after you stop earning, while what's left keeps growing. This calculator projects your monthly expense forward to your retirement age, sizes the corpus needed to fund it for your expected lifespan, and checks that against what your current savings and monthly investment are on track to become.
If there's a shortfall, it also shows the additional monthly SIP needed to close the gap.
How the required corpus is estimated
The "real rate" is your post-retirement return adjusted for inflation — it’s what lets the corpus keep paying out a rising, inflation-matched expense for n years (your years in retirement) rather than a flat amount that loses purchasing power.
This model necessarily simplifies a genuinely complex, personal decision — it doesn’t account for pension income, EPF/NPS payouts, or lump-sum expenses like a child’s education. Treat the output as a directional check, not a plan to follow to the rupee.
Worked example: the default scenario, and why inflation moves it so much
A 30-year-old with ₹50,000 in current monthly expenses, retiring at 60 and planning to age 85, with 6% assumed inflation, 11% pre-retirement and 7% post-retirement returns, ₹5,00,000 in existing savings and a ₹15,000 monthly SIP already running: that same ₹50,000 monthly expense becomes roughly ₹2,87,175 a month by retirement, purely from 30 years of inflation. Funding that inflated expense for a 25-year retirement requires a corpus of roughly ₹7.71 crore. The current savings trajectory is projected to reach about ₹5.58 crore — a shortfall of roughly ₹2.13 crore, closeable with an additional ₹7,540 a month on top of the existing SIP.
Now change only the inflation assumption, from 6% to 8%, leaving every other input untouched: the required corpus jumps to roughly ₹16.91 crore — more than double. Nothing else about the plan changed; a 2-percentage-point difference in a single assumption, compounded over 30 years of accumulation and 25 years of withdrawal, did that entirely on its own.
Why this calculator is a starting point, not a full plan
Retirement planning has moving parts this model doesn’t attempt to capture: medical costs that historically inflate faster than general expenses, a lump-sum need like a child’s education or wedding landing mid-plan rather than spread evenly, a pension or annuity income stream that reduces how much the corpus itself needs to fund, or a desire to leave money behind rather than draw the corpus to zero. Use this to sanity-check the *order of magnitude* of the gap between where you’re headed and where you need to be — and treat a real retirement plan, especially within a decade of retiring, as worth building with a financial planner who can account for what a single calculator can’t.
Frequently asked questions
What return should I assume before vs. after retirement?
Pre-retirement, many people use a higher, more equity-heavy assumption (10–12%) since the horizon is longer. Post-retirement, a more conservative, capital-preservation-oriented rate (6–8%) is common since the money needs to last with less risk.
Does this include my EPF, NPS or pension?
Only if you include it in "existing savings" — the calculator doesn’t automatically add any other income sources. For a fuller picture, add your expected EPF/NPS maturity value to the existing savings field.
Why does a small inflation change move the required corpus so much?
Because inflation compounds over both the accumulation and withdrawal years — a 2% swing in assumed inflation, stretched over 30–40 years, changes the target corpus far more than intuition suggests. The worked example above shows this exact effect with real numbers.
What if the calculator shows a "surplus" instead of a shortfall?
It means your current savings and monthly investment, projected forward at your assumed pre-retirement return, are on track to exceed the corpus needed — a reasonable position to be in, though it’s still worth re-checking periodically as your actual expenses, returns and life plans evolve.
Should I use my current expenses or my expected retirement expenses?
Enter your current monthly expenses — the calculator inflates them forward to estimate what the equivalent lifestyle costs at retirement. Some expenses (commuting, a home loan EMI that ends) may fall in retirement while others (healthcare) typically rise; this model doesn’t split that out, so treat "current expenses" as a reasonable proxy rather than a precise forecast.
How often should I recalculate this?
At least once a year, or whenever a major input changes — a raise, a new monthly SIP, a change in your target retirement age. Small annual course-corrections are far easier to make than a large one discovered a few years before retiring.
Does the required additional SIP account for the step-up most people apply to their SIP over time?
No — it assumes a flat, unchanging monthly SIP for the entire accumulation period. If you plan to increase your investment amount over time (which most people’s income allows), use the Step-Up SIP Calculator to see how a smaller starting increase can close the same gap.