FIRE Calculator

Your FIRE number is the portfolio large enough that withdrawing from it covers your living expenses indefinitely. One division does it:

At the classic 4% rule, that's just 25× your annual spending. Spend $50,000 a year and you need $1,250,000. Spend $80,000 and you need $2,000,000. Drop the withdrawal rate to 3.5% and the same $50,000 spender needs about $1,430,000 instead — a 14% larger portfolio for a safety margin that a 40-year retirement arguably requires.

Notice what isn't in the formula: income. Two people earning $200,000 can have FIRE numbers a million dollars apart, because only spending sets the target. Income determines how fast you get there; spending determines where “there” is.

That's also why cutting an expense is worth roughly 25 times what it looks like. Trimming $400 a month — $4,800 a year — takes $120,000 off your FIRE number while simultaneously freeing $4,800 a year to invest. No raise does both.

Once your spending sets the target, the only thing that decides the timeline is what share of your take-home pay you invest. Starting from zero, at a 5% real return and a 4% withdrawal rate, the years to financial independence run like this:

Read the jumps, not the rows. Going from a 10% savings rate to 20% cuts fourteen years off. Going from 50% to 60% cuts five. The curve is steepest where most people start, which is why the first serious cut to spending is the most valuable thing an aspiring early retiree ever does. To find where you sit on this table today, run your income and monthly savings through the savings rate calculator.

Every dollar you stop spending works twice: it raises the numerator of your savings rate and lowers the FIRE number in the denominator of the goal. A raise you spend entirely does neither. And the sooner those dollars are invested, the more of the work compounding does for you — the green portion of the chart above is money you never had to earn.

The FIRE community sorts itself by annual spending. The labels are informal — nobody issues certificates — but they capture a real difference in what the same math demands of you. All three use the same 25× rule; only the input changes.

Lean FIREgets you out fastest, because a small target and a high savings rate reinforce each other. The cost is margin. A $900,000 portfolio funding $36,000 a year has almost no slack for a medical surprise, a bad first decade of returns, or a child you didn't plan on. Lean FIRE assumes you stay flexible — willing to earn a little, move somewhere cheaper, or cut back for a year.

Fat FIREbuys that margin back. Retiring on $120,000 a year means a $3,000,000 portfolio and, for most people, a decade or more of extra work. In exchange, you never change your lifestyle, a 30% drawdown doesn't threaten your plan, and a 3.5% withdrawal rate is affordable rather than aspirational.

Most people land in between, and many pass through the neighbors on the way. Barista FIRE covers most expenses from the portfolio and the rest from part-time work — often for the health insurance. Coast FIRE comes earlier still: you stop contributing entirely and let compounding carry the balance to your FIRE number by a normal retirement age. Run yours in the Coast FIRE calculator — it's usually reached years before people expect.

The 4% rule comes from the Trinity Study, which tested 30-year retirements against historical market data. Someone leaving work at 40 is planning for 50 years, and the rule was never tested there. Three adjustments are worth making:

• Consider 3.25–3.5% instead of 4%.It raises your FIRE number from 25× spending to roughly 29–31×. Run both in the calculator — the gap between the two timelines is the price of the safety margin, and it's usually smaller than people fear.
• Sequence risk is the real threat.A bad first few years of returns, while you're selling shares to live on, does permanent damage that an identical crash a decade later would not. The average return in your plan says nothing about the order it arrives in.
• Flexibility beats precision. Retirees who trim spending in down years, or earn a little, survive scenarios that a rigid inflation-adjusted withdrawal does not. A part-time year early on is worth more than a percentage point of assumed return.

One more assumption worth naming: the calculator above uses a realreturn, so your spending stays in today's dollars and inflation is already netted out. If you enter a 10% nominal return next to today's spending, you'll shave years off a timeline that hasn't actually moved. See what inflation does to a nominal number in the inflation-adjusted returns calculator.