Retirement Corpus and Monthly Investment Gap Calculator

Q: How much corpus do I need to retire comfortably?

It depends on your expected post-retirement annual expenses (adjusted for inflation to your retirement year), how many years you expect to be in retirement, and what return your corpus can safely generate during retirement. There is no single number — use the calculator with your own expense and horizon estimates.

Q: Why does the calculator use inflation-adjusted expenses instead of today's expenses?

Because retirement may be years or decades away, today's expenses will cost significantly more by then due to inflation — using today's figure directly would understate your real retirement need.

Q: What if I can't afford the monthly investment gap shown?

Consider adjusting the levers available to you: extending your working years, increasing your expected investment return (within your risk tolerance) by reviewing asset allocation, or realistically revising planned retirement expenses — closing a large gap usually needs a combination of these rather than one alone.

Project retirement funding

This is a deterministic projection; actual returns, inflation, taxes and longevity will vary.

Required corpus at retirement

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Projected funding gap

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Measure	Amount
First-year retirement expense	—
Projected corpus from current plan	—
Required total monthly investment now	—
Additional monthly investment	—

How This Is Calculated

This calculator projects your target retirement corpus (based on inflation-adjusted expenses and years in retirement), compares it against your current savings trajectory, and shows the monthly investment gap — the additional amount you'd need to invest regularly to close the shortfall, given your expected pre-retirement rate of return.

Frequently Asked Questions

How much corpus do I need to retire comfortably? ▼

Why does the calculator use inflation-adjusted expenses instead of today's expenses? ▼

What if I can't afford the monthly investment gap shown? ▼

Methodology, assumptions and sources

Scope: Computes the retirement corpus required to sustain a target post-retirement monthly expense, and the monthly investment gap between what the user is currently saving and what is required.

Calculation logic

Required retirement corpus = using the entered post-retirement monthly expense (inflated to the retirement year), retirement duration (life expectancy − retirement age), expected post-retirement return and inflation, computed via the present value of a growing annuity (to account for the corpus needing to sustain inflation-adjusted withdrawals through retirement).

Future value of current retirement savings and ongoing monthly investment (if any) is projected forward to retirement age using standard compound growth.

Investment gap = Required additional monthly SIP to bridge the shortfall between the projected corpus (from current savings/investment) and the required corpus, solved using the standard SIP future-value formula.

Inputs and assumptions

Life expectancy/retirement duration, and pre- and post-retirement expected return rates, are user-entered planning assumptions, not guarantees.

Post-retirement expense is assumed to grow with inflation throughout the retirement period, and the corpus is assumed to earn a (typically lower, more conservative) post-retirement return as entered.

Exclusions and edge cases

Does not separately model pension income (EPS, NPS annuity, etc.) unless the user nets it out of the required post-retirement monthly expense before entering it.

Does not model healthcare cost inflation separately from general inflation unless the user adjusts the expense assumption.

Sources

No specific external regulatory source applies beyond general market-linked instrument mechanics.

Review status: reviewed and approved by CA Nikhil Gupta on 14 July 2026.