FinanceCalcs
Financial Independence (FIRE) Calculator
Calculate your FI number - the portfolio size that lets you retire and live off investment returns indefinitely. See how many years until you reach financial independence based on your current savings rate, and compare Lean FIRE, Regular FIRE, and Fat FIRE targets.
Based on the 4% safe withdrawal rule and Trinity Study research. Adjust your spending, savings rate, and return assumptions to model your own path.
Financial Independence (FIRE) Calculator
Savings Rate: 0% | SWR: 4%
FI in -- years - Age --
- Portfolio
- FI Target
Your FIRE Journey - Year by Year
| Age | Annual Savings | Portfolio | FI Target | % of FI | Years to FI |
|---|
FIRE Variants Comparison
| Type | Annual Spend | FI Number |
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Post-FIRE Sustainability
"Financial independence is not about being rich. It's about having options."
- JL Collins, The Simple Path to Wealth
How the FIRE calculation works
The FIRE (Financial Independence, Retire Early) framework rests on two core concepts: the FI Number and the safe withdrawal rate.
Your FI Number is the portfolio size at which you can live indefinitely off investment returns without depleting principal. It's calculated as: Annual Spending ÷ Safe Withdrawal Rate. At the 4% rule, that's 25× your annual expenses. If you spend $60,000/year, your FI number is $1,500,000.
The 4% rule comes from the Trinity Study (1998), which found that a portfolio of 50-75% stocks / 25-50% bonds had a 95%+ success rate over 30-year retirement periods at a 4% initial withdrawal rate (inflation-adjusted). More recent research suggests 3.3-3.5% may be safer for early retirees with 40-60 year horizons, but 4% remains the community standard.
How long it takes depends almost entirely on your savings rate. At a 10% savings rate it takes about 43 years. At 50% it takes about 17 years. At 75% it takes about 7 years. The relationship is highly non-linear - small increases in savings rate dramatically shorten the timeline, especially at higher rates.
lightbulb Years to FIRE by Savings Rate
Assumes 7% real return, starting from zero, spending all non-saved income:
| Savings Rate | Years to FIRE | FI Age (starting 30) |
|---|---|---|
| 10% | ~43 years | 73 |
| 20% | ~37 years | 67 |
| 30% | ~28 years | 58 |
| 40% | ~22 years | 52 |
| 50% | ~17 years | 47 |
| 65% | ~10.5 years | 41 |
| 75% | ~7 years | 37 |
The savings rate is the most powerful lever in the FIRE equation - far more impactful than investment return assumptions over the accumulation phase.
FIRE FAQs
What are the different types of FIRE?
Lean FIRE - achieving FI on a very frugal budget (typically under $40K/year). Requires a smaller portfolio but leaves little margin for unexpected expenses. Regular FIRE - FI at your current lifestyle spending. Fat FIRE - FI with significant spending above current lifestyle ($100K+/year), providing maximum security and flexibility. Barista FIRE - partially FI but still doing part-time work for income, health insurance, or enjoyment.
Is the 4% rule safe for early retirees?
The original Trinity Study modeled 30-year retirements. For early retirees with 40-60 year horizons, many researchers suggest 3.0-3.5% is more conservative. The FIRE community often uses 4% as the baseline but builds in flexibility - reducing spending in bad market years ("variable withdrawal strategies") or maintaining some income sources like part-time work or rental income.
Does the FI number account for inflation?
Yes - in the 4% rule framework, withdrawals increase with inflation each year. The FI number represents today's dollars in spending, and the investment return assumption should be a real (inflation-adjusted) return. This calculator uses your stated inflation rate to adjust the FI target and portfolio projections.
What about Social Security and other income?
Any guaranteed income you'll receive in retirement reduces your FI number. If you'll get $20,000/year from Social Security and need $70,000/year in expenses, you only need to cover $50,000/year from your portfolio - so your FI number is $1,250,000 instead of $1,750,000. Use the "Other Retirement Income" field to account for this.
FIRE terminology
FI Number (Financial Independence Number)
The portfolio size at which you can retire sustainably. Formula: Annual Retirement Spending ÷ Safe Withdrawal Rate. At 4% SWR, your FI number = 25× annual spending.
Safe Withdrawal Rate (SWR)
The percentage of your portfolio you can withdraw in year one (then adjust for inflation annually) with high historical confidence of not running out of money. The 4% rule comes from the 1998 Trinity Study. Lower rates (3-3.5%) are more conservative for longer retirements.
Savings Rate
Annual savings divided by annual gross income. The single most important lever in the FIRE equation. At a 50% savings rate, for every year you work you save enough to fund roughly one year of retirement. The math is that direct.
Sequence of Returns Risk
The risk that poor investment returns early in retirement permanently impair a portfolio, even if long-run averages are fine. A 30% market drop in year 2 of retirement at 4% withdrawal is far more damaging than the same drop in year 20. This is why most FIRE practitioners hold 2-5 years of expenses in bonds/cash as a buffer.
Coast FIRE
The point at which your current portfolio, if left untouched, will grow to your FI number by traditional retirement age - meaning you no longer need to save, just cover living expenses. Many use Coast FIRE as an intermediate milestone.
Barista FIRE
A hybrid approach: partially FI but working part-time for supplemental income, health insurance, or purpose. Named after a common example - barista jobs at chains like Starbucks historically offered health insurance to part-time employees.
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