Enter your numbers and get your coast date — the age your existing savings can compound to your full retirement number on their own — plus your Coast, Barista and Full FIRE numbers, and a 1,000-run Monte Carlo stress test over 98 years of historical market returns. Everything runs in your browser; nothing is uploaded.
1,000 simulated lifetimes, each year bootstrapped from 98 years of historical US stock & bond real returns (1928–2025, estimates). Bands show the 10th–90th and 25th–75th percentile range; the bright line is the median. Today's dollars throughout.
Download your full Coast FIRE number-by-age schedule (CSV), the year-by-year Monte Carlo projection (CSV), and a polished one-page PDF report — then save and reload unlimited named plans beyond Scenario A/B. Everything runs on your device; nothing is uploaded.
Try it now: demo code AV-COASTFIRE-SIM-DEMO previews every Pro feature on this device.
Once you hit coast, the job is simple: low fees, broad diversification, and don't touch it.
Track your progress to Coast, Barista and Full FIRE month by month — with the same math this simulator uses, plus net-worth milestones and a savings-rate dashboard. Join the list and we'll send it over.
Coast FIRE is the moment your retirement savings reach escape velocity. It's the point where the money you've already invested — left completely alone — is projected to compound into your full retirement number by your target retirement age. From that day on you can stop contributing to retirement accounts entirely. You still need a job to pay this month's rent and groceries, but every paycheck is yours to spend: no more "save 25% first." People use coast as permission to downshift to a lower-stress career, start a business, or go part-time decades before traditional retirement.
Two cousins are worth knowing. Barista FIRE means semi-retiring early and covering part of your spending with relaxed part-time work, while a (smaller) portfolio covers the rest. Full FIRE means the portfolio covers everything. This simulator computes all three numbers from the same four inputs.
Your Full FIRE number is annual spending divided by your safe withdrawal rate (at 4%, that's 25× spending). Your coast number at any age is that FIRE number discounted back by expected real growth:
The simulator walks forward month by month: your balance grows with returns and contributions while the coast target grows as your runway shrinks. The age where the two lines cross is your coast date — the headline number at the top of the page.
A single "7% per year" projection hides the thing that actually ruins early retirements: sequence-of-returns risk. Retiring into a 1973-74 or 2000-02 style crash can sink a plan that would have sailed through average markets. So alongside the simple projection, this tool runs 1,000 simulated lifetimes. Each simulated year draws a random year from our embedded table of historical US stock and 10-year Treasury real returns, 1928–2025 (estimates compiled from public sources; 2025 provisional), keeping stock and bond returns from the same year paired so crashes hit both sides realistically. Your portfolio contributes until your coast date, coasts until retirement, then withdraws your spending every year. The success probability is simply the share of those 1,000 lifetimes where money lasted to your plan-until age. The fan chart shows the spread: the middle line is the median lifetime, and the shaded bands are the 25–75% and 10–90% percentile ranges.
Across the 98 embedded years, stocks compounded at roughly ~6.7% real and 10-year Treasuries at roughly ~1.4% real — which is why the default deterministic assumption is a deliberately humbler 5% real.
The 4% rule comes from studies of 30-year retirements over US history, and it survived the Great Depression and 1970s stagflation in those backtests. But early retirees often face 40–60 year horizons, where many researchers suggest 3.25–3.75% instead. Rather than argue, edit the withdrawal rate in the assumptions panel and watch the success probability respond — that's the honest answer.
Coast FIRE keeps your full salary lifestyle but ends saving; Barista FIRE cuts your hours but requires a bigger portfolio than coast-at-the-same-age (because you start withdrawing the gap sooner). If your job is fine but saving feels suffocating, coast is the natural target. If the job itself is the problem, look at your Barista number.
Yes — by sidestepping it. Every figure is in today's dollars and every return in the simulation is a real (inflation-adjusted) return. "$48,000/yr spending" means $48,000 of today's purchasing power in every future year.
Anything invested for the long term and earmarked for retirement: 401(k)/IRA balances, taxable brokerage index funds, vested employer shares you intend to diversify. Leave out your emergency fund, home equity you'd never sell, and money for near-term goals.
It means that in 850 of 1,000 simulated market histories, your plan never ran out of money before your plan-until age. It is not a guarantee — and the remaining 15% isn't doom, either, because real people adjust spending in bad markets rather than withdrawing blindly. Most planners treat 80–90% as a solid plan with flexibility as the backstop.
Yes — both scenarios are encoded into the page URL as you type. Hit "Copy share link" and send it; the recipient sees exactly your inputs, including the A/B comparison.
Yes. Pick your country at the top and every figure — your savings, contributions, spending, the Coast, Barista, Lean, Full and Fat FIRE numbers, the chart and the exports — switches to your local currency. The model is currency-neutral, so your coast age and Monte Carlo success probability are identical in any currency; only the displayed amounts change. Rates are approximate planning estimates.
It's the lump sum that, invested at a given age with no further contributions, is projected to grow into your full FIRE number by your target retirement age. It climbs every year you wait, because there's less time left to compound — which is exactly why starting early is so powerful. The age-by-age table on this page shows that number beside your projected balance, and highlights the age where the two cross: your coast date.
The free tool gives you the full simulator, the 1,000-run Monte Carlo, the age-by-age coast table and A/B compare. Pro adds a CSV of the coast-by-age schedule, a CSV of the year-by-year projection (all five percentile bands), a one-page printable PDF report, and a saved-plan library you can reload anytime — every file generated on your device with nothing uploaded.
Keep building the plan: map your monthly cash flow with the Smart Budget planner, weigh buying a home against renting in the Rent vs Buy calculator, and check your fitness age and longevity odds with LongeviQ. Want to own this simulator offline? Get the Pro download in the store →