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Retirement / FIRE Calculator
Corpus needed, monthly saving and the 4% rule — with SWR sensitivity, coast-FIRE, real return, and a Monte-Carlo survival check. Accurate, instant and free — for US · India.
What these mean:
What these mean:
What these mean:
You need $2,093,778 by age 65 to fund 30 years of retirement.
Remaining balance
360 mosHow retirement corpus, monthly saving, and decumulation are calculated
This calculator combines three engines: (1) inflate today's expenses to the retirement date; (2) divide by the chosen SWR to size the corpus; (3) invert the SIP/FV formula to find the required monthly saving. Decumulation runs a year-by-year drawdown using the SWP engine, rising with inflation each year. Real return always uses the Fisher relation — never naive subtraction.
Corpus sizing (SWR method)
Inflate expenses → divide by SWR
Eₑ = E₀ × (1 + inflation)^years
corpus = Eₑ ÷ SWR
- E₀ = today's annual expense
- Eₑ = expense at retirement
- SWR = Safe Withdrawal Rate (default 4%)
- 4% SWR → 25×; 3.5% → 28.57×; 3% → 33.3×
Real return — Fisher relation
Not nominal − inflation
real = (1 + nominal) ÷ (1 + inflation) − 1
- 6% nominal, 3% inflation: 1.06/1.03 − 1 = 2.91%
- Naive subtraction (6%−3% = 3%) is wrong
- 9 bps error compounds to ~2% on corpus over 30 years
All accumulation and decumulation steps use Fisher real return.
Required monthly SIP (inversion)
How much to save each month
SIP = (C − S×(1+i)^n) × i ÷ ((1+i)^n − 1)
- C = corpus needed
- S = current savings (compounded forward)
- i = monthly real return
- n = months to retirement
Existing savings are grown forward and netted before sizing the SIP.
Decumulation (year-by-year drawdown)
Does the corpus last?
corpusₙ₊₁ = (corpusₙ − withdrawalₙ) × (1 + post-ret. return)
withdrawalₙ = Eₑ × (1 + inflation)^(year − 1)
- Withdrawals rise with inflation each year (not flat)
- Flags the year corpus depletes (or survives)
- Pre-retirement return ≠ post-retirement return allowed
- 1US / FIRE — 4% SWR vs 3.5% SWR on $40,000/yr: $40,000/yr at 4% SWR: corpus = $40,000 ÷ 0.04 = $1,000,000 (25×). At 3.5% SWR (early-retiree, 50–60 yr horizon): $40,000 ÷ 0.035 = $1,142,857 (28.57×) — $142,857 more. To reach $1M from $0 in 25 years at 5% real return (annual SIP): $1,000,000 × 0.05 / ((1.05)^25 − 1) ≈ $20,950/yr ≈ $1,746/mo (annual-compounding convention). Monthly compounding (this calculator) gives ≈ $1,679/mo — a 4% difference from the period convention.
- 2India — ₹50,000/mo today, 6% inflation, retire in 30 years: Expense at retirement: ₹50,000 × 12 × (1.06)^30 ≈ ₹34.5 lakh/yr (≈ ₹2.87 lakh/mo). At 4% SWR: corpus ≈ ₹8.6 crore. This is the 25×-snapshot floor — the SWP decumulation with rising withdrawals over a long Indian retirement (6–7% CPI) can require materially more. The snapshot multiplier is a sizing reference; the year-by-year drawdown table is the survival test.
- 3Fisher real return — 6% nominal / 3% inflation: Fisher: (1.06 / 1.03) − 1 = 2.91% real. Naive subtraction: 6% − 3% = 3% — an overstatement of 9 bps. Over 30 years on $1,000: 3% grows to $2,427; 2.91% to $2,375 — a $52 gap per $1,000. On a $1M corpus, the compounding error is ~$52,000 in sizing.
Projections assume constant returns — real sequences vary
The 4% rule — where it comes from, and when to use 3.25–3.5%
The 4% rulehas a specific, citable origin: it is not a rule of thumb invented by bloggers. William Bengen's 1994 study across rolling US 30-year windows found that 4% was the highest withdrawal rate (the SAFEMAX) that never depleted a portfolio in any historical period. The Trinity Study (1998) confirmed it with a “portfolio success rate” framing across 1926–1995. Both studies assume a 30-year horizon and a balanced portfolio.
4% SWR — standard
30-yr horizon (Bengen/Trinity)
25×
annual expenses
$40,000/yr → $1,000,000
Calibrated for retire-at-65, plan-to-95 (30 years).
3.5% SWR — early retiree
~50-yr horizon (FIRE at 40–50)
28.57×
annual expenses
$40,000/yr → $1,142,857
ERN, madFIentist, Vanguard consensus for 50–60 yr horizons.
3% SWR — ultra-conservative
60+ yr or high-uncertainty
33.3×
annual expenses
$40,000/yr → $1,333,333
Conservative buffer for non-US markets or very early retirement.
Early retirees: use 3.25–3.5%, not 4%
- 1Bengen (1994) — the SAFEMAX origin: William Bengen, “Determining Withdrawal Rates Using Historical Data,” Journal of Financial Planning (1994). Analyzed rolling US 30-year periods from 1926–1993. Found 4% was the highest rate that never depleted a 50/50 stock-bond portfolio in any historical window — called the SAFEMAX.
- 2Trinity Study (1998) — portfolio success rates: Cooley, Hubbard & Walz, “Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable,” AAII Journal (1998). Framed the 4% rule as a portfolio success rateacross 1926–1995 — e.g. “95% of 30-year periods survived a 4% withdrawal rate on a 75/25 portfolio.” Popularized the rule for practitioners and the public.
- 3Why 30-year studies don't cover FIRE: A 40-year-old retiring today with a 90-year life expectancy has a 50-year horizon— far outside both studies' window. Historical 50-year success rates at 4% are lower. The adjustable SWR in this calculator lets you choose 3.25–3.5% explicitly. A SWP Calculator can run the year-by-year drawdown at your chosen rate.
Why a constant-return line misleads — and how survival probability changes the picture
A deterministic projection — “your $1M at 5% real return lasts 30 years” — is a single path through one assumed average. Real returns arrive in a sequence, not an average. A bad first decade (2000–2009 US equities: −0.95%/yr real) can permanently impair a corpus even if the 30-year average “works out” on paper.
Sequence — bad decade first
$1M, 4% SWR, 6% avg but −5% yr 1–5
Even if years 6–30 average 10%, the portfolio has taken $40K+/yr withdrawals on a shrunken base for five years.
Historical example: retire in 2000 with a 60/40 portfolio — by 2010, the “average return” line said corpus survived; the actual corpus was severely depleted.
Sequence matters more than average in the first decade of retirement.
Sequence — good decade first
Same avg return, growing first
Strong early returns mean withdrawals come from a larger base. The portfolio's remaining compounding power is preserved.
A retiree who retired in 2010 (post-GFC) with identical inputs had a materially better outcome than one who retired in 2000, despite similar long-run market returns.
Same inputs, opposite sequence → opposite outcome.
- 1Lower your SWR — the primary lever: Moving from 4% to 3.5% is not just a 0.5% adjustment — it builds a 12.5% larger corpus ($1,142,857 vs $1,000,000 on $40K/yr) that can absorb a bad first decade while still withdrawing the inflation-adjusted amount.
- 2Cash buffer / bucket strategy: Hold 2–3 years of expenses in cash or short-duration bonds. Avoid selling equities in down years by drawing from the cash bucket. Refill the bucket from equities when markets recover. This does not change the long-run SWR math but reduces the probability of forced selling at the worst time.
- 3Flexible spending — reduce withdrawals in bad years: Research (Pfau, Kitces) shows that accepting a 10–15% withdrawal cut in years of negative returns dramatically improves survival rates. Variable spending rules (e.g., Guyton-Klinger) outperform rigid constant-dollar withdrawals on long horizons. This calculator uses a constant-withdrawal baseline; adjust the SWR downward for a conservative plan.
Monte Carlo survival bands
Healthcare inflates at 8–10% — not 3%. Why a single inflation rate under-sizes your corpus
General CPI inflation in the US runs roughly 3%; in India roughly 6–7%. But healthcare — which grows as a share of retirement spending from ~10% at 65 to ~30%+ at 80 — inflates at 8–10% per year in the US (KFF, CMS actuarial data). Using a single general CPI rate for all retirement expenses materially understates the corpus needed for late-retirement years.
| Expense bucket | Share at 65 | Inflation rate | 20-yr corpus impact |
|---|---|---|---|
| General living (housing, food, leisure) | ~90% | 3% (US CPI) | baseline |
| Healthcare (premiums, out-of-pocket, LTC) | ~10% → 30%+ at 80 | 8–10% p.a. | +15–25% corpus |
Healthcare inflation estimate: KFF Health System Tracker, CMS National Health Expenditure data. “+15–25% corpus” is an illustrative range; exact impact depends on healthcare share, years in retirement, and individual health trajectory.
- 1Split your budget into two buckets: General expenses (housing, food, travel, leisure) and healthcare (insurance premiums, Medicare/Medigap, long-term care insurance, out-of-pocket). Use ~3% for general and 8–10% for healthcare.
- 2Compound each bucket separately to retirement age: General bucket: today_general × (1.03)^years. Healthcare bucket: today_healthcare × (1.09)^years. Sum the two inflation-adjusted streams to get total retirement expense_at_retirement, then divide by SWR for corpus. This gives a more accurate corpus than a single blended rate.
- 3In the decumulation table, escalate each bucket at its own rate: Healthcare's share of total spending rises with age, compounding the late-retirement shortfall risk. A corpus sized at 65 using a single 3% rate may appear sufficient until the mid-70s, when healthcare becomes the dominant expense.
India: medical inflation runs 6–10% vs 6–7% general CPI
Coast FIRE: when you can stop saving — and honest depletion age
Coast FIRE is the savings level at which your current portfolio, left to compound without further contributions, will grow to your full retirement corpus by your target retirement age. Once you reach it, you only need to earn enough to cover current expenses — savings can stop.
Coast FIRE number
How much you need invested today
coast = corpus ÷ (1 + real)^years_to_retire
- $1,000,000 corpus at 65, 5% real, age 35 (30 yrs):
- coast = $1,000,000 / (1.05)^30 = $231,377
- Once invested, zero further contributions needed
Honest depletion age
When does the corpus run out?
The decumulation table shows the year the corpus hits zero— or confirms it survives to life expectancy. A plan that “works at the average” may deplete at 82 with a bad sequence.
Depletion age is the honest output. This calculator will not clamp to “lasts forever” when the math says otherwise.
- 1What changes when you hit coast FIRE: You can switch to a lower-paying job, go part-time, take a sabbatical, or pursue passion work — as long as current earned income covers current expenses. You no longer need to generate surplus for retirement savings.
- 2What doesn't change — you still need to fund current life: Coast FIRE is not regular FIRE. You cannot stop working entirely (unless income covers current expenses without touching the invested corpus). The portfolio is untouched and compounding; withdrawals only begin at the planned retirement date.
- 3The coast number shrinks dramatically with time invested: The 30-year example above requires $231,377. At age 25 (40 years to retirement), the coast number at 5% real drops to $1,000,000 / (1.05)^40 = $142,046 — $89,000 less than the age-35 number. Every year of early investing cuts the coast target. See the Compound Interest Calculator to model the time-value effect.
Frequently asked questions
Divide your inflation-adjusted annual retirement expenses by your Safe Withdrawal Rate (SWR). At 4% SWR: corpus = expense ÷ 0.04 = 25×. At 3.5% SWR: 28.57×. Always inflate today's expenses first:expense_at_retirement = today × (1+inflation)^years. Then divide by SWR. A SIP Calculator can compute the monthly saving needed to reach that corpus, and a SWP Calculator can model the annual drawdown through retirement.
The 4% rule was established by William Bengen in “Determining Withdrawal Rates Using Historical Data,” Journal of Financial Planning (1994) — the SAFEMAX study across rolling 30-year US windows. It was popularized and stress-tested by the Trinity Study (Cooley, Hubbard & Walz, 1998), which modeled “portfolio success rates” over 1926–1995. Both assume a 30-year horizon and a balanced portfolio. Corpus multipliers: 4% → 25×, 3.5% → 28.57×, 3% → 33.3×. See the NPS Calculator for a pension-backed corpus baseline.
No — not comfortably. The 4% rule was calibrated for a 30-year horizon (retire at 65, plan to 95). For a FIRE retirement spanning 50–60 years, both historical-cohort and Monte Carlo analyses show a materially higher failure rate at 4%. The early-retiree consensus (ERN, madFIentist, Vanguard) is to use ~3.25–3.5% SWR. At 3.5%, the 25× rule becomes 28.57×: $40,000/yr requires $1,142,857 — $142,857 more than at 4%. Use the Compound Interest Calculator to model your accumulation, and the SWP Calculator to stress-test drawdown over your target horizon.
Use the Fisher relation: real = (1+nominal) / (1+inflation) − 1. At 6% nominal, 3% inflation: 1.06 / 1.03 − 1 = 2.91% — NOT 3% (the naive 6% − 3% is wrong by ~9 bps). Over 30 years on $1,000: 3% → $2,427; 2.91% → $2,375 — a $52 gap per $1,000 of corpus. This calculator uses Fisher throughout. For a nominal return view, compare with the PPF Calculator (sovereign nominal rate) or Compound Interest Calculator.
Coast FIRE is the savings threshold at which your current portfolio, compounding without further contributions, reaches your full retirement corpus by target retirement age: coast_number = corpus_needed / (1+real)^years. Example: $1,000,000 corpus at 65, 5% real return, age 35 → coast number = $231,377. Once reached, you stop optimising savings and can work for income or passion only. Related: a SIP Calculator models the accumulation path; an NPS Calculator adds a pension floor; the PPF Calculator provides a sovereign-backed safe base.
Method, assumptions & references
Methodology: corpus = inflation-adjusted annual expense ÷ SWR (4% SWR → 25×; 3.5% → 28.57×; 3% → 33.3×). Inflation adjustment: expense_at_retirement = today's expense × (1+inflation)^years. Real return: Fisher relation (1+nom)/(1+infl)−1 — not naive subtraction. Required SIP: FV inversion netting existing savings. Decumulation: year-by-year with inflation-adjusted withdrawals; flags depletion age honestly. Worked goldens: US $40K/yr @ 4% SWR = $1,000,000; @ 3.5% = $1,142,857; India ₹50K/mo, 30yr, 6% infl = ₹8.6 crore. SWR provenance: Bengen (1994) SAFEMAX, Trinity Study (1998). Early-retiree caveat (50–60 yr horizon): use 3.25–3.5%, not 4%. Fisher real return: 6% nom / 3% infl = 2.91%, not 3%.
Related calculators
How we calculate this
Reviewed by Reckonist Editorial · Last reviewed 16 June 2026. Figures follow the methods and sources set out in our editorial standards.
Projections assume constant returns; sequence-of-returns risk is real; SWR is a planning reference, not a guarantee. Bengen (1994) and Trinity (1998) assume a 30-year horizon and US historical data — early retirees with 50–60 year horizons should use 3.25–3.5% SWR. Fisher real return used throughout (not naive subtraction). Healthcare inflation (8–10%) materially raises the corpus beyond CPI-only models. Not financial advice — consult a CFP or SEBI-registered investment adviser for personal retirement planning.
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