What’s Your FIRE Number? Calculate Your Real Financial Independence Target
Last updated: July 2026. Your “FIRE number” — the portfolio size where you could theoretically live off withdrawals indefinitely — is the central number in the Financial Independence, Retire Early movement, and it’s built on one specific, well-researched rule. Our free FIRE Number Calculator applies that rule to your actual annual expenses and shows how many years your current savings and contributions need to get there.
Where the 4% rule actually comes from
The 4% figure traces back to the “Trinity Study,” academic research that tested how various withdrawal rates would have performed across rolling historical 30-year periods of U.S. market returns. A 4% initial withdrawal, increased with inflation each year, held up in the large majority of those historical periods without depleting the portfolio — which is mathematically the same as needing roughly 25 times your annual expenses saved, since 1 ÷ 0.04 = 25. This is why you’ll hear FIRE described as “saving 25x your expenses” and “the 4% rule” interchangeably; they’re the same math stated two ways.
Why expenses matter more than income for this number
Because the FIRE number is built entirely from annual expenses, not income, two people earning identical salaries can end up with wildly different FIRE numbers depending on their lifestyle. This is also why cutting spending has a double effect on your timeline: it lowers the target you’re saving toward and frees up more money each month to save toward it. It’s the reason the FIRE community focuses so heavily on optimizing recurring expenses, rather than treating a higher income as the only lever available.
Adjusting the rate for a longer or shorter retirement
The 4% figure was tested against a roughly 30-year retirement horizon. Someone retiring in their 30s or 40s under FIRE is planning for a much longer retirement than that, which is why many FIRE planners use a more conservative 3–3.5% withdrawal rate instead — equivalent to a 28.6x–33.3x multiple of expenses rather than 25x. Try running the calculator at both 4% and 3.5% side by side to see how much that single assumption changes your target number and timeline.
What the 4% rule doesn’t account for
The 4% rule is a historical guideline, not a guarantee — it was tested against past market conditions, and future returns, inflation, and sequence-of-returns risk (a run of poor returns early in retirement) could all affect real-world outcomes differently. It also doesn’t account for Social Security or pension income, which can reduce the portfolio withdrawal actually needed later in a traditional retirement. Building in a margin of safety, whether through a lower withdrawal rate or a higher target, is a common and reasonable adjustment.
Calculate your own number
Head to the FIRE Number Calculator, enter your annual expenses, and see your target instantly, along with an estimated timeline based on your current savings and contribution rate. If you’re weighing a lower-risk milestone before full FIRE, our Millionaire Timeline Calculator can track progress toward any interim target along the way.
Disclaimer: Freedom Wealth Lab provides general financial education, not personalized advice. Investing involves risk, including possible loss of principal; past performance does not guarantee future results. Please read our full Disclaimer and Affiliate Disclosure before acting on anything you read here. The 4% rule is based on the “Trinity Study” (Cooley, Hubbard & Walz, 1998) using historical U.S. market data.
