FinMathFinMath

FIRE / Retirement Calculator

When can you retire? Project your Financial Independence date using real returns, the 4% rule, and Monte Carlo simulation.

How to read this calculator (click to collapse)

FIRE stands for Financial Independence, Retire Early. You are financially independent when your invested portfolio is large enough that withdrawing a small percentage each year — classically 4% — covers your annual expenses indefinitely. "Retirement" here means freedom from wage income, not an age.

Rule of thumb: once your assets reach 25× your annual expenses, you can safely draw 4% per year (adjusted for inflation) and the portfolio has historically lasted 30+ years (Trinity Study, 1998).

What each input means

InputWhat it is
CurrencyAll amounts use this currency — keep it consistent.
Current AgeYour age today.
Current Invested SavingsMoney already invested in stocks, bonds, ETFs, mutual funds — not idle cash or bank savings.
Monthly ContributionHow much you add to investments every month (retirement accounts + taxable).
Annual Expenses in RetirementYour expected cost of living per year, in today's money. The calculator inflates it automatically.
FIRE MultiplierTarget = multiplier × annual expenses. 25 = 4% rule. Use 28–33 for conservative (Lean/Safe FIRE).
Withdrawal RateThe inverse of the multiplier (1/25 = 4%). Set this or the multiplier — they update together.
Expected Return (nominal)Your portfolio's expected annual return before subtracting inflation. A globally diversified stock portfolio has historically returned ~8–10% nominal.
InflationAssumed annual inflation rate. Indonesia ≈ 4–5%, USA ≈ 2–3%, Eurozone ≈ 2%.
Return Volatility (σ)Year-to-year swings used for Monte Carlo. Stock-heavy ≈ 15–20%, balanced 60/40 ≈ 10–12%, bond-heavy ≈ 5–8%.

How to read the results

  • Time to FIRE — years needed to reach the target. FIRE at age = your current age + years to FIRE.
  • FIRE Target — total portfolio value you need (in today's money). Equals multiplier × annual expenses.
  • Real Return — your nominal return after inflation, via the Fisher equation (1+rnom)/(1+π) − 1. If this is negative, your purchasing power is shrinking every year and FIRE becomes very slow or impossible.
  • Monthly Income (Withdrawal) — expected monthly payout in retirement = annual expenses ÷ 12.
  • Success Rate (MC) — across 1,000 Monte Carlo simulations with random yearly returns, the share that reach the target within the horizon. Aim for ≥ 85%.
  • Chart — the dashed yellow line is the FIRE Target; the solid cyan curve is the expected path (deterministic); the shaded band is the p10–p90 range across Monte Carlo scenarios (worst 10% to best 10%).

Common pitfall

If you enter an Expected Return that is lower than Inflation, the real return goes negative and the Time to FIRE explodes. That is not a calculator bug — it reflects the fact that cash or very low-yield portfolios lose ground to inflation. For a realistic plan, use an expected return that matches your actual allocation (e.g. 8–10% nominal for a diversified stock-heavy portfolio).

Your Numbers

$
$
Total of all retirement accounts + taxable investment contributions per month.
$
Estimate your cost of living in retirement, in today's money. This calculator handles inflation automatically.
25 = 4% rule. Use 28–33 for conservative (Lean/Safe FIRE).
%
%
%
Time to FIRE
—
—
USD
FIRE Target
—
Real Return
—
Monthly Income (withdrawal)
—
Success Rate (MC)
—

What Is FIRE?

FIRE — Financial Independence, Retire Early — is a framework for ending wage dependence as early as possible by saving aggressively and investing in broad-market assets. The core mechanic: once your portfolio is large enough that a safe withdrawal rate covers your annual expenses, you're financially independent. Work becomes optional.

The 4% Rule Explained

The famous "4% rule" comes from the 1998 Trinity Study, which back-tested US stock/bond portfolios over rolling 30-year windows. It found that a 4% initial withdrawal rate (adjusted annually for inflation) had a very high historical success rate — roughly 95%+ for 50/50 or 60/40 allocations over 30 years.

Converting this to a target: if you spend $40,000/year, you need $40,000 / 0.04 = $1,000,000 — that is, 25× annual expenses. This calculator defaults to 25× but lets you set a more conservative multiplier (28×, 33×) for longer retirement horizons or Lean/Safe FIRE.

Real Returns, Not Nominal

A 30-year retirement plan denominated in today's dollars must use real returns, not nominal. The Fisher relation:

rreal = (1 + rnominal) / (1 + inflation) − 1

A 7% nominal return with 3% inflation gives a ~3.88% real return. That single adjustment can change your FIRE date by 5-10 years. All projections on this page are in real terms — both the target and the growth curve.

Monte Carlo vs Deterministic Projection

Constant-return projections are misleading because returns vary. A 7% average might mean +22%, -5%, +12%, +18%, -14%, +9% — and the order matters a lot in the withdrawal phase (sequence-of-returns risk).

Enable Monte Carlo to run 1,000 random paths using your expected return and volatility assumptions. The "Success Rate" is the percentage of paths that reach the FIRE target within the projected horizon. For a robust plan, aim for 85-95% success.

Savings Rate Is the Dominant Variable

Counterintuitive but true: your savings rate matters far more than your return. Classic Mr. Money Mustache math:

  • Save 10% of income → ~51 years to FIRE
  • Save 25% → ~32 years
  • Save 50% → ~17 years
  • Save 70% → ~8.5 years

Every 1% increase in savings rate cuts years off your FIRE date, regardless of market returns. Focus on the income-expense gap, not on squeezing extra basis points from your portfolio.

Variants of FIRE

  • Lean FIRE — minimalist lifestyle, target $500K-$1M, 25-30× expenses
  • Standard FIRE — ~$1M-$2.5M, 25× expenses, 4% rule
  • Fat FIRE — higher lifestyle, $2.5M+, 25-33× expenses
  • Coast FIRE — accumulate enough that compounding alone reaches FIRE by traditional retirement age; stop contributing
  • Barista FIRE — portfolio covers most expenses; part-time work covers the rest and provides healthcare

Regional Considerations

The 4% rule is US-centric. Indonesian, Russian, and Indian savers face higher inflation and often higher returns — adjust assumptions accordingly. For example, Indonesia's multi-decade inflation has averaged ~4-5%, so a 10% nominal equity return translates to ~5% real. European savers with 2-year negative rates (2020-2022) have historically needed higher savings rates.

Limitations

This tool simplifies: constant volatility (no regime-switching), no Social Security / pension integration, no tax-account segregation (pre-tax vs Roth vs taxable), no changing expenses across life stages. For more advanced modeling, see the VaRisk Kancil platform (portfolio-level risk analytics).

Related Tools