What is Financial Independence (FIRE)?
Financial Independence, Retire Early (FIRE) is a personal finance movement built on a simple idea: save and invest enough that your portfolio generates passive income to cover your expenses indefinitely — without ever needing to work again.
The classic milestone is reaching 25× your annual expenses — known as your "FI number". At a 4% safe withdrawal rate, this amount has historically sustained 30+ year retirements based on US market data (the Trinity Study).
How to calculate your FI number
FI number = Annual expenses ÷ Safe withdrawal rate
Example: $3,000/month in expenses → $36,000/year → FI number = $36,000 ÷ 0.04 = $900,000.
FIR€$ goes further than this simple formula. It simulates your portfolio year by year, accounting for salary growth, inflation, capital gains tax, debt repayment, pension income, and one-time events like inheritances or property purchases.
Key features
- Monte Carlo simulation
- Runs thousands of randomised market scenarios to estimate the probability that your portfolio survives throughout retirement. A success rate above 90% is generally considered robust.
- Year-by-year projections
- See exactly how your net worth, savings rate, and passive income evolve each year from today until end of life — in a sortable, paginated table.
- Sensitivity analysis
- Understand which variables matter most: how much does your FI date shift if returns drop 1%, or if you cut expenses by 10%? The sensitivity chart answers these questions instantly.
- Life changes & future events
- Schedule income or expense changes over time (part-time work, kids leaving home) and model one-time cash flows like inheritances, bonuses, or large purchases.
- 9 languages supported
- Available in English, French, German, Spanish, Portuguese, Italian, Dutch, Polish, and Chinese — automatically detected from your browser.
Frequently asked questions
- What is a safe withdrawal rate (SWR)?
- The safe withdrawal rate is the percentage of your portfolio you can withdraw each year without running out of money. The most cited figure is 4%, derived from the Trinity Study. FIR€$ lets you adjust this rate to match your risk tolerance.
- How long does it take to reach financial independence?
- It depends primarily on your savings rate. Saving 10% of income typically takes 40+ years; saving 50% can get you there in roughly 17 years; saving 75% in around 7 years. FIR€$ calculates your exact timeline based on your personal numbers.
- What is the difference between lean FIRE, fat FIRE, and barista FIRE?
- Lean FIRE means retiring on a minimal budget (below $40k/year). Fat FIRE targets a comfortable lifestyle ($100k+/year). Barista FIRE involves semi-retirement with part-time work to cover some expenses. You can model all three scenarios in FIR€$ by adjusting your monthly expenses.
- Does FIR€$ store my data?
- No. All calculations happen entirely in your browser. Your inputs are saved only in your local storage and never sent to any server. You can share your scenario via the Share button, which encodes all data directly in the URL.