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.
Two coworkers, same $95,000 salary, a $750,000 gap
John and Wei work the same job, earn the identical $95,000 salary, and both plan to retire under the standard 4% rule. John lives in a modest apartment, cooks most meals at home, and keeps his annual spending to $40,000 — his FIRE number is $40,000 × 25 = $1,000,000. Wei carries a bigger mortgage, leases a newer car, and travels several times a year, landing his annual expenses at $70,000 — his FIRE number is $70,000 × 25 = $1,750,000, a $750,000 gap between two people with the identical paycheck.
Assuming both save aggressively and invest at a 7% average return, that $750,000 gap doesn’t just change the finish line, it changes how many working years separate them — John could plausibly reach financial independence close to a decade before Wei, purely from the expense side of the equation, with no difference in income at all. If you want to see exactly how a lower target compounds into an earlier date given your own contribution rate, our Compound Interest Calculator lets you run both targets side by side.
The common mistake: forgetting healthcare when you retire early
One of the most common gaps in a DIY FIRE number is healthcare. Someone retiring at 62 with employer coverage simply continues paying the same premium they always did through COBRA or a new plan; someone retiring at 40 loses employer coverage decades before Medicare eligibility at 65, and has to buy an individual health plan on the open market for the entire gap. A mid-tier individual or family marketplace plan commonly runs $700–$1,200 a month, or roughly $8,400–$14,400 a year, and that cost usually isn’t in a retiree’s pre-FIRE budget at all because an employer was quietly absorbing most of it.
Added to annual expenses before multiplying by 25, that single line item raises a FIRE number by roughly $210,000 to $360,000. For someone planning an early retirement decades before Medicare kicks in, running the calculator once with your current expenses and once with a realistic healthcare premium added is one of the more sobering — and useful — five minutes you can spend on this plan.
Healthcare isn’t the only pre-retirement cost that quietly disappears once you have a job. Employer 401(k) matches, subsidized commuter benefits, and even the simple structure of a workplace can mask the true cost of your lifestyle. It’s worth building a bare “post-paycheck” budget from scratch rather than assuming your current spending, minus a few obvious line items, is the real number your FIRE target should be built on.
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 genuinely 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.
Why the accumulation phase matters as much as the number itself
A FIRE number tells you where the finish line is, but it says nothing about how you get there, and the path matters more than people assume. Two savers with the identical $1,000,000 target and identical $500 monthly contribution can arrive years apart depending on their assumed return, their starting balance, and how consistently they genuinely keep contributing through market downturns rather than pausing when a portfolio drops. Our Compound Interest Calculator lets you model that accumulation phase directly — starting balance, monthly contribution, and return — so you can see not just your target but a realistic path and timeline toward it.
It’s also worth revisiting your FIRE number periodically rather than calculating it once and filing it away. Rent increases, a growing family, or a move to a higher cost-of-living area can all push annual expenses up meaningfully, and because the FIRE number is 25 times that figure, even a modest $5,000 increase in yearly spending raises the target by $125,000. Recalculating annually, alongside a normal budget review, keeps the number honest rather than anchored to whatever your expenses happened to be the year you first ran it.
The same logic runs in reverse, too. Someone who successfully trims a recurring subscription, refinances a car loan, or moves to a lower cost-of-living city doesn’t just save money in the moment — they permanently lower their FIRE number by 25 times whatever that annual saving turns out to be. A $200-a-month reduction in ongoing expenses, sustained indefinitely, is $2,400 a year, which lowers the FIRE target by $60,000. Small, permanent changes to a monthly budget tend to matter more to this particular number than most people expect on first glance.
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.
