Retirement Corpus Calculator: How Much Do You Actually Need?

"How much have I saved" is the wrong question

Ask ten people how much they need to retire and most will answer with a round number pulled from a magazine article or a parent's old benchmark — a crore, five crore, a million dollars. Very few can explain why that number, specifically, is the right one for their life.

The right question is not "how much have I saved" but "how much do my actual expenses, my expected retirement length, and my withdrawal assumptions say I need." That reframes retirement corpus from a vague aspiration into a calculation you can run, check, and update every year.

This guide walks through the retirement corpus formula step by step, with full INR and USD examples, and flags the assumptions — especially around withdrawal rate — that carry real uncertainty and deserve conservative treatment rather than optimistic rounding.

The core retirement corpus formula

At its simplest, the retirement corpus formula is: Corpus needed = Annual expenses ÷ Withdrawal rate. If you spend ₹9,00,000 a year and plan to withdraw 4% of your corpus annually, you need roughly ₹2,25,00,000 (₹9,00,000 ÷ 0.04) in today's rupees.

The same math in USD: $54,000 in annual expenses at a 4% withdrawal rate implies a corpus of $1,350,000 ($54,000 ÷ 0.04). Multiplying annual expenses by 25 (the reciprocal of 4%) produces the identical result and is the more commonly cited shorthand.

This is the accumulation-phase target in today's money. It says nothing yet about inflation between now and your retirement date, or about how long your money needs to last once you start withdrawing — both of which we adjust for next.

Corpus multiple by withdrawal rate assumption

The withdrawal rate you choose has an outsized effect on the corpus you need, because it sits in the denominator. A more conservative (lower) withdrawal rate demands a proportionally larger corpus — and that conservatism is often justified for longer retirement horizons, as we cover in detail in our dedicated guide to the safe withdrawal rate and the 4% rule.

Why withdrawal rate assumptions should shift with horizon length

A withdrawal rate that survived historical 30-year U.S. retirement periods is not automatically safe for a 40- or 50-year horizon, which is exactly the situation many FIRE-focused early retirees face when leaving the workforce in their 30s or 40s rather than their 60s.

Longer horizons generally call for lower withdrawal rates (more conservative corpus multiples) because there is more time for a bad sequence of returns, unexpected expenses, or extended inflation to compound against a fixed nominal spending plan. This is a nuanced, genuinely debated area of retirement research — treat any single withdrawal rate as a planning starting point that should be stress-tested, not a guarantee, and revisit our safe withdrawal rate guide for the full caveats before finalizing a number for an early retirement horizon.

Adjusting for inflation between now and retirement

The corpus figure from the core formula is expressed in today's money. If retirement is 20 years away, your actual future annual expenses — and therefore your actual future corpus target — will be considerably higher in nominal terms, even though your real (inflation-adjusted) spending power stays the same.

For India, a common long-run planning inflation assumption is 5.5–6%, though healthcare and education have historically run hotter. For the U.S., 2.5–3% is a typical long-run baseline. Over a 20-year horizon at 6% inflation, today's ₹9,00,000 annual expense grows to roughly ₹28,80,000 in nominal terms by year 20 — which is the number that should actually feed your future corpus calculation, not today's ₹9,00,000.

The cleanest way to avoid confusion is to do all your planning in real (inflation-adjusted) terms: use today's expenses, a real (post-inflation) expected return, and a real withdrawal rate throughout. That keeps every number comparable without needing to separately inflate and deflate figures at each step.

Adjusting for a longer retirement horizon

A 60-year-old retiring with a 25–30 year horizon and a 45-year-old retiring with a 40–45 year horizon are solving different math problems, even with identical annual expenses. The early retiree's money needs to survive far more years, absorb more inflation compounding, and weather more market cycles.

This is why early retirement (FIRE) planning generally leans toward the lower end of the withdrawal-rate table above — 3–3.5% rather than 4–5% — and toward a larger cash or bond buffer to reduce the damage from a poorly timed downturn early in retirement, a risk explored fully in our sequence of returns risk guide.

Sensitivity: how corpus needs shift with retirement age

Retirement age affects the corpus calculation in two compounding ways: a longer remaining horizon typically calls for a more conservative withdrawal rate (a larger corpus multiple), and a longer horizon also means more years of accumulated inflation before you can stop contributing and start relying on the portfolio.

The table below illustrates how the corpus multiple alone shifts by retirement age, holding annual expenses in today's money constant. It does not include the separate, often larger effect of nominal inflation compounding over a longer accumulation period, which is addressed earlier in this guide.

Step-by-step: calculating your own retirement corpus

Step 1 — Establish your true annual expenses from actual trailing spending, not an aspirational budget. Include annual and irregular costs divided into a monthly or annual average.

Step 2 — Choose a withdrawal rate appropriate to your expected retirement length. Traditional retirees around age 60 with a ~30-year horizon often use 4%; early retirees with 40+ year horizons often use 3–3.5% for a larger safety margin.

Step 3 — Divide annual expenses by the withdrawal rate (or multiply by the corresponding corpus multiple) to get your base corpus in today's money.

Step 4 — Project that expense figure forward to your target retirement date using a reasonable inflation assumption, then recalculate the nominal corpus needed at that future date — or simply keep everything in real terms and skip this step, provided you also use a real return assumption for accumulation.

Step 5 — Add buffers for healthcare, long-term care, and any known large future expenses (a child's education, a parent's care) that are not part of routine annual spending.

Step 6 — Subtract the present value of any guaranteed income you'll receive in retirement — pension, EPS, annuity, or Social Security — from the required corpus, since that guaranteed income reduces how much your portfolio alone needs to fund.

Corpus needed by expense level (INR and USD)

The table below shows how the corpus target scales across expense levels and withdrawal rate assumptions, so you can locate your own situation and see how sensitive the target is to the withdrawal rate you choose.

Worked example: an Indian professional retiring at 55

Vikram, 38, plans to retire at 55 — a 17-year accumulation horizon and an expected 35-year retirement given family longevity. His current annual expenses are ₹10,80,000 (₹90,000/month). Because his post-retirement horizon is long, he chooses a conservative 3.5% withdrawal rate rather than the traditional 4%.

Base corpus in today's money: ₹10,80,000 ÷ 0.035 ≈ ₹3.09 crore. Assuming 6% inflation over 17 years, his expenses in nominal terms at age 55 grow to roughly ₹27,45,000/year, implying a nominal corpus target at retirement of approximately ₹7.84 crore.

Vikram expects a modest EPS pension of about ₹1,20,000/year in nominal terms at 55, which reduces the portfolio-funded portion of his expenses slightly. He also adds a 10% healthcare buffer given the long horizon, nudging his working target corpus to roughly ₹8.4–8.6 crore nominal — a number he revisits and adjusts annually as actual inflation and expenses come in.

Because a 17-year, then 35-year, combined horizon is unusually long to project with confidence, Vikram treats this nominal figure as a directional planning target rather than a fixed commitment, and plans to re-run the calculation with updated real inflation and expense data every year rather than anchoring rigidly to today's projection a decade from now.

Worked example: a U.S. professional retiring at 60

Sarah, 45, plans to retire at 60 — a 15-year accumulation horizon and an expected 30-year retirement. Current annual expenses are $60,000. Given the more traditional 30-year horizon, she uses the standard 4% withdrawal rate.

Base corpus in today's money: $60,000 ÷ 0.04 = $1,500,000. Assuming 2.8% average inflation over 15 years, her expenses in nominal terms at 60 grow to roughly $90,700/year, implying a nominal corpus target of approximately $2,267,500.

Sarah expects Social Security benefits of roughly $28,000/year in today's dollars starting at 62–67 depending on the claiming age she chooses, which meaningfully offsets her portfolio-funded need once benefits begin — though she conservatively models her corpus assuming a later claiming age and treats early benefits as a bonus buffer rather than a core assumption.

Healthcare and long-term care buffers

Healthcare costs tend to rise faster than headline inflation and tend to concentrate later in retirement, which is exactly when a portfolio has the least time left to recover from a shortfall. A dedicated buffer — commonly 10–20% added to the base corpus, or a separate ring-fenced healthcare/long-term-care fund — is a reasonable adjustment for both Indian and U.S. retirees.

In India, comprehensive health insurance that continues into retirement (rather than relying solely on an employer policy that ends at retirement) is a critical input that should be priced into the annual expense figure, not treated as an afterthought. In the U.S., Medicare eligibility typically begins at 65, which creates a coverage gap for anyone retiring earlier that must be explicitly budgeted for — marketplace premiums before 65 can be a substantial line item that early retirees frequently underestimate.

Pension, EPS, Social Security, and annuity offsets

Any guaranteed income stream in retirement — a defined-benefit pension, EPS in India, Social Security in the U.S., or an annuity — reduces the amount your investment portfolio alone needs to fund, and should be subtracted from your gross expense figure before applying the withdrawal-rate formula.

Be conservative when estimating these offsets. Social Security benefit estimates can change with policy, EPS payouts depend on contribution history and rules that can shift, and annuity income depends on the issuer's ongoing solvency. Model guaranteed income at a discount to the official estimate, and treat the difference as an additional margin of safety rather than fully relying on the headline projected figure.

Calculating corpus for a household, not just an individual

Most retirement corpus calculators, including the formula in this guide, implicitly assume a single expense figure — but households with a spouse, dependents, or aging parents need to model shared and individual expenses carefully rather than simply doubling an individual's number.

Shared fixed costs — housing, utilities, one household's worth of insurance — do not scale linearly with the number of people, while genuinely individual costs — healthcare, personal spending, education for children — should be modeled per person and added on top of the shared base. Two working spouses each independently calculating a full individual corpus based on their personal share of household spending, without coordinating, commonly overstates or understates the true household target depending on how costs were allocated.

For joint retirement planning, it is usually cleaner to build one combined annual household expense figure, apply the corpus formula once to that combined figure, and then track progress against a single shared corpus target rather than maintaining two separate individual calculations that need constant reconciliation.

Legacy and inheritance goals

If leaving an inheritance or funding a specific legacy goal matters to you, that changes the corpus math meaningfully. A pure "spend it all down responsibly" retirement plan can tolerate a slightly higher withdrawal rate than a plan that also aims to preserve a meaningful principal balance for heirs or a cause.

A common adjustment is to plan withdrawals against a lower rate (for example, 3% instead of 4%) so that the corpus is more likely to remain largely intact rather than depleting toward zero, effectively building in a legacy buffer as a byproduct of a more conservative baseline withdrawal assumption.

Corpus needs differ by FIRE variant

The corpus formula is identical across FIRE variants — what changes is the annual expense figure you plug in. Lean FIRE plans around a minimal, tightly controlled expense base, producing a smaller corpus target. Fat FIRE plans around a more comfortable, higher-spending lifestyle, producing a proportionally larger target for the same withdrawal rate.

Barista FIRE and Coast FIRE both assume some continued part-time or passive income alongside portfolio withdrawals, which effectively lowers the corpus your investments alone need to cover, since a portion of expenses is met from ongoing work income rather than withdrawals. We explore each variant's specific trade-offs and typical numbers in dedicated guides elsewhere in this series — this guide focuses on the underlying corpus math that applies regardless of which variant you're targeting.

Underestimating your corpus: common mistakes

Mistake 1 — Basing the expense figure on current spending while ignoring known future increases like a mortgage payoff timeline, children's education costs, or planned relocation.

Mistake 2 — Applying today's expenses directly to a future retirement date without adjusting for inflation, which understates the true nominal corpus needed by a wide margin over long horizons.

Mistake 3 — Using the traditional 4% withdrawal rate for a 40+ year early retirement horizon without adjusting toward a more conservative rate, understating the corpus needed for the added years of exposure.

Mistake 4 — Ignoring healthcare cost inflation, which often outpaces general inflation and disproportionately affects later retirement years.

Mistake 5 — Overestimating guaranteed income offsets (pension, EPS, Social Security) based on optimistic official projections rather than conservative, discounted estimates.

Mistake 6 — Calculating a household corpus by simply adding two individually estimated numbers without reconciling shared fixed costs, which can meaningfully overstate the true combined target.

Overestimating your corpus: the hidden cost of over-saving

Corpus anxiety cuts both ways. Extremely conservative assumptions stacked on top of each other — a very low withdrawal rate, high inflation assumption, large buffers, and discounted guaranteed income all applied simultaneously — can produce a corpus target so large that it demands working years, or savings sacrifice, well beyond what is actually necessary.

Every additional year spent accumulating beyond a genuinely well-reasoned corpus target is a year of income, health, and time not spent on whatever retirement was meant to free up. Stack reasonable, individually defensible assumptions rather than maximally conservative ones at every single step, and revisit the target with updated real data annually rather than freezing it at an overly cautious estimate made years earlier.

From a single number to a probability-based target

Every calculation in this guide produces a single point estimate based on fixed assumptions. Real portfolios experience volatility, and a single corpus number cannot tell you the probability that your actual retirement, with actual market returns in actual sequence, will succeed.

As you approach your target date, it's worth running your corpus and spending plan through a Monte Carlo simulation, which models thousands of randomized return sequences and reports a success probability alongside percentile outcome ranges — a fundamentally more honest way to evaluate whether a specific corpus is "enough." Our guide to Monte Carlo simulation for retirement planning walks through exactly how to do this.

Tracking your progress toward your corpus target

A corpus target is only useful if you can see how close you actually are to it, updated with real numbers rather than a mental estimate. Consolidating retirement accounts, mutual funds, EPF/PPF/NPS, and brokerage holdings into a single tracked net worth view turns "I think I'm on track" into a specific, current percentage of your target.

Capitallytics tracks multi-asset net worth automatically and pairs it with free retirement and FI calculators, so you can compare your live invested corpus against your calculated target without rebuilding a spreadsheet every few months.

Annual corpus recalculation checklist

Update your annual expense baseline from actual trailing spending, including any new recurring costs.

Recheck your inflation assumption against recent actual inflation trends, without overreacting to a single unusual year.

Reconfirm your chosen withdrawal rate is still appropriate for your (possibly shifting) expected retirement horizon.

Re-estimate guaranteed income offsets conservatively based on the latest official figures available to you.

Compare your live tracked net worth against the recalculated corpus target and note the gap or surplus.

If you're within striking distance of your target, run a probability-based simulation before making any irreversible retirement decision.

Conclusion: a defensible number beats a round number

"How much do I need to retire" has a real, calculable answer once you commit to actual expenses, a horizon-appropriate withdrawal rate, and honest inflation and offset assumptions — not a round number borrowed from someone else's plan.

Build the calculation conservatively but not paranoically, recalculate it every year as your life and the economy change, and escalate to probability-based modeling before making irreversible decisions like leaving a stable income. The goal is a corpus target you can actually defend, not just recite.

Educational content only — not personalized financial, tax, or investment advice. Verify numbers for your situation and consult a qualified professional when decisions are material.