Use this free financial independence calculator to find your FI number - the invested portfolio size at which you no longer need to work - and estimate how many years it will take to get there. Based on the Financial Independence, Retire Early (FIRE) formula and the 4% safe withdrawal rate rule.
FI Number = Annual Expenses / Safe Withdrawal Rate
At 4% SWR: FI Number = Annual Expenses x 25
Annual Surplus = Annual Income - Annual Expenses
Savings Rate = Annual Surplus / Annual Income x 100
Current Passive Income = Current Savings x SWR
Example: Annual expenses $48,000, withdrawal rate 4%. FI Number = $48,000 / 0.04 = $1,200,000. With $120,000 already saved and $36,000/year to invest at 7% annual return, monthly simulations project FI in approximately 17 years.
Financial independence rests on a simple principle: if your invested assets generate enough annual return to cover your expenses, you have no need for employment income. The challenge is that this requires a large investment base relative to typical savings rates.
The safe withdrawal rate determines the required multiple of annual expenses. At 4%, you need 25x. At 3%, you need 33x. Reducing your annual expenses not only lowers your FI number directly but also increases your annual surplus (the amount you're investing each year), accelerating the timeline from both directions simultaneously.
The current passive income stat shows what your existing portfolio already generates at your withdrawal rate. This number grows as your portfolio grows, giving you increasing financial runway even before full FI. Many people find this figure motivating to watch grow over time.
| Withdrawal rate | FI multiplier | Notes |
|---|---|---|
| 5.0% | 20x | Aggressive; risk of premature depletion over 30+ years |
| 4.0% | 25x | Trinity Study standard; strong historical success over 30 years |
| 3.5% | 28.6x | Conservative; preferred for 40-50 year early retirements |
| 3.0% | 33.3x | Very conservative; high confidence for extreme longevity |
| 2.5% | 40x | Ultra-safe; used for perpetual endowments and multi-generational wealth |
Your FI number is a direct function of your annual expenses and your chosen withdrawal rate. It tells you the exact portfolio size at which you could stop working and live off investment returns indefinitely based on historical market data. The most powerful way to lower it is to reduce annual expenses - every $1,000 per year you cut saves $25,000 in required FI portfolio.
Your savings rate is the single most important variable in determining your FI timeline. It is not just about how quickly you accumulate wealth - it also tells you how little you need to retire. A 50% savings rate means you live on half your income, so your expenses are low, and your FI number is lower too. This double effect makes each percentage point of savings rate disproportionately valuable.
This is the annual income your current portfolio theoretically generates at your safe withdrawal rate. It grows as your portfolio grows, providing a real-time gauge of your FI progress. When your passive income equals your annual expenses, you are FI. Tracking this number yearly (or quarterly) is more motivating than tracking portfolio balance alone.