FIRE Calculator
Find your Financial Independence number, exact Freedom Day date, and Monte Carlo survival rate. 4 FIRE types — Lean, Regular, Fat, Coast. Free, no signup.
Last reviewed: March 2026
What Is the FIRE Movement?
FIRE — Financial Independence, Retire Early — is a movement centered on saving aggressively (typically 50–70% of income) to build a portfolio large enough to sustain your lifestyle indefinitely from investment returns alone. The core math is simple: save until your portfolio is 25× your annual expenses (the "4% rule"), then retire.
Popularized by Vicki Robin and Joe Dominguez's Your Money or Your Life (1992) and modernized by bloggers including Mr. Money Mustache, ChooseFI, and Karsten Jeske ("Big ERN"), FIRE has grown into an active community on r/financialindependence and early-retirement.org, with variants including Lean FIRE (minimal spending), Fat FIRE (full lifestyle), Barista FIRE (part-time work covers some expenses), and Coast FI (stop saving and let compounding finish the job).
How to Calculate Your FIRE Number
The FIRE Formula
FI Number = Annual Expenses ÷ Safe Withdrawal Rate
Example: $50,000/yr expenses ÷ 0.04 = $1,250,000 FI Number
The 4% rule originates in William Bengen's 1994 SAFEMAX paper ("Determining Withdrawal Rates Using Historical Data") and was refined by the 1998 Trinity Study (Cooley, Hubbard, Walz), which found a 60/40 stock-bond portfolio supported 4% inflation-adjusted withdrawals across every rolling 30-year US market period from 1926 forward. For a 40–50 year early-retirement horizon, Karsten Jeske ("Big ERN") and Morningstar both recommend stress-testing at 3.25–3.5%.
Once you have your FI number, your years-to-FIRE depends on your savings rate. The Shockingly Simple Math of Early Retirement shows that a 50% savings rate means FIRE in ~17 years; 60% means ~12 years; 75% means ~7 years.
The 4 Types of FIRE — Which Path Is Right for You?
Lean FIRE
Retire on 50% of average US expenses (~$25,000/year). Maximum frugality. FI number ≈ 12.5× current expenses. Best for: minimalists, geographic arbitrageurs, those valuing freedom above lifestyle.
Regular FIRE
Retire maintaining your current lifestyle. FI number = 25× current annual expenses (4% rule). The classic FIRE target — retire without changing your spending habits.
Fat FIRE
Retire with 150%+ of current lifestyle expenses — luxury, travel, private schools. FI number ≈ 37.5× current expenses. Best for: high earners who don't want to compromise lifestyle.
Coast FI
You've saved enough that compound growth alone reaches your FI number by age 65 — no more contributions required. You can "coast" with lower-stress work, cover current expenses without saving, and let time do the heavy lifting.
The Savings Rate Is Your Superpower
Your savings rate — the percentage of income you invest — is the single biggest lever in your FIRE timeline. Even small increases have dramatic effects:
Assumes 7% real returns, starting from $0. Source: MMM "Shockingly Simple Math".
What Is Monte Carlo Simulation for Retirement?
Monte Carlo simulation runs thousands of randomized market scenarios to test your plan's robustness. Instead of assuming a steady 7% annual return, it uses historical volatility (S&P 500 std dev ≈ 17%) to simulate good years, bad years, and devastating crashes in sequence.
The most dangerous scenario for FIRE is a major crash in your first 3–5 years of retirement — called sequence-of-returns risk. Monte Carlo reveals this: a plan that "works" on average may only survive 75% of scenarios when you account for bad timing.
Most FIRE planners target 90%+ Monte Carlo survival. The FIRE community generally considers 95%+ "bulletproof." This calculator runs 1,000 simulations instantly in your browser.
Methodology & Assumptions
This calculator uses an iterative year-by-year simulation (not closed-form), which handles growing income, increasing expenses, and Social Security income more accurately than simple formulas. The accumulation phase projects your portfolio with real annual returns applied to the year-end balance plus contributions. The drawdown phase models annual withdrawals reduced by Social Security and part-time income.
Monte Carlo uses Box-Muller transformed Gaussian random variables with mean = your expected return and standard deviation = 17% (S&P 500 historical). All calculations run entirely in your browser. No financial data leaves your device.
Frequently Asked Questions
What is the FIRE number formula?
FIRE number = Annual expenses ÷ Safe withdrawal rate. Using the 4% rule (Bengen 1994 SAFEMAX): $50,000/year × 25 = $1,250,000. At that portfolio size, a 60/40 stock-bond mix historically supported 4% inflation-adjusted withdrawals across every rolling 30-year US market period from 1926 forward without depletion.
Should I use a 3.5% or 4% safe withdrawal rate?
The 4% rule was calibrated by Bengen (1994) and the Trinity Study (Cooley, Hubbard, Walz 1998) for 30-year retirements. For a 50–60 year early-retirement horizon, Karsten Jeske ("Big ERN") argues for ~3.25–3.5% in his Safe Withdrawal Rate Series. Morningstar's 2023 "State of Retirement Income" research revised the starting-safe rate up to 4.0% given current bond yields, so 3.5% is conservative, 4% is mainstream, 4.5% is aggressive for early retirees.
What is Coast FI?
Coast FI is the portfolio size at which compound growth alone — with zero new contributions — reaches your full FIRE number by age 65. Formula: Coast FI = FIRE number ÷ (1 + r)^(65 − current age). At r = 7% real, a 30-year-old needs only ~$170K invested to coast to a $1.25M FIRE number by 65. You keep working to cover current expenses but stop saving.
What is Lean FIRE vs Fat FIRE vs Barista FIRE?
Lean FIRE: retire on ~$25–40K/year (≈12.5× expenses × 25). Regular FIRE: maintain current lifestyle (25× current expenses). Fat FIRE: ≥150% of current lifestyle (~37.5× expenses). Barista FIRE: portfolio plus part-time income covers expenses — often chosen to access subsidized health insurance. The right target depends on your spending floor, geographic flexibility, and healthcare strategy.
What is sequence-of-returns risk?
A 30–40% market drop in years 1–5 of retirement, combined with fixed withdrawals, can permanently deplete a portfolio even if long-term average returns are normal. Retirees who started in 1966 or 2000 faced this and several Trinity-style cohorts failed. The Monte Carlo engine here runs 1,000 randomized sequences (mean = your expected return, σ = 17%, the S&P 500 historical standard deviation) to expose this risk explicitly rather than masking it in an average.
What savings rate do I need to retire in 10 years?
From a $0 starting portfolio at 7% real returns, a ~65% savings rate reaches 25× expenses in about 10 years. This is the core insight of Mr. Money Mustache's "Shockingly Simple Math of Early Retirement" (2012): 50% saved → ~17 years, 65% → ~10 years, 75% → ~7 years. A meaningful starting portfolio (e.g., 5–10× expenses already invested) cuts the required rate substantially — run your numbers above to see your specific timeline.
Does the 4% rule still work in 2026?
Yes, though with caveats. Morningstar's 2023 update ("The Good News on Safe Withdrawal Rates") raised its recommended starting rate to 4.0% for 30-year horizons, reversing a 2021 downgrade, citing improved bond yields. For early retirement horizons of 40–60 years, Jeske ("Big ERN") and others have shown the 4% rule fails in a meaningful minority of historical sequences, which is why Monte Carlo survival rates and flexible withdrawal strategies (guardrails, CAPE-based rates) matter more than a single static number.
Should I include home equity in my FIRE number?
No — unless you plan to downsize or sell. A primary residence does not produce withdrawable cash flow and your annual expenses already include housing costs (mortgage, property tax, maintenance). The ChooseFI and r/financialindependence consensus: exclude home equity from your invested assets total. Include only taxable brokerage, 401(k)/IRA, HSA, and cash reserves that you can realistically draw down at 4%.