Setting the Target — How Much You Actually Need for FI

Your FIRE number is the multiple of your annual retirement spending that lets you stop working. At a 4% withdrawal rate, that multiple is 25× — so $50,000 of annual spending implies $1,250,000 invested. Spend less and the target falls. Pick a more conservative withdrawal rate and the target rises. Almost everything else in FI is a story about closing the gap between today and this number.

Financial independence has many definitions floating around but only one piece of arithmetic at its core: a portfolio that can support your annual spending forever. "Forever" is doing a lot of work in that sentence, and the framework for converting "forever" into a single dollar figure is what this page is about. The math is small; the implications are not. Most people who would benefit from knowing their number have never actually written it down.

The formula is one line

Your FIRE number equals your projected annual retirement spending divided by your safe withdrawal rate. At a 4% withdrawal rate that division is the same as multiplying by 25, which is why the rule of thumb you have probably already heard is "25× annual spending." The formula does not care about your income, your career, or your savings rate — those determine how fast you get there, not where "there" is.

The two levers

The formula has only two inputs, which makes the calculator easy to use and the underlying question harder than it looks. The first lever is spending. A retiree spending $40,000/year needs $1,000,000 at 4%; a retiree spending $80,000/year needs $2,000,000. Every dollar of recurring annual spending costs you twenty-five dollars of portfolio. That is the strongest argument ever made for examining whether a subscription, a second car, or a third bedroom is actually worth what it pretends to be — the portfolio cost is roughly twenty-five times the sticker.

The second lever is the withdrawal rate. Pick 4% and you are using the standard baseline calibrated for a 30-year retirement. Pick 3.5% and you have built in a margin appropriate for a longer horizon or for someone who is uncomfortable depending on portfolio math at the edge. Pick 4.5% and you are accepting more risk that a poor first decade of returns forces a spending cut. The sandbox shows all three rates simultaneously so you can see how sensitive the target is to the choice. It is sensitive — moving from 4% to 3.5% lifts the target by about 14%.

Lean, Standard, Fat — same math, different lifestyles

The FI community has informal names for common spending tiers. They are not different rules; they are the same formula applied to different spending levels. Lean FIRE describes a minimalist retirement around $30,000/year, often involving lower cost of living, modest housing, and a deliberately simple lifestyle. Standard FIRE sits around $60,000/year, roughly the spending of a comfortable middle-class household. Fat FIRE begins above $100,000/year and describes a retirement that preserves a high-income household's pre-retirement lifestyle, including travel, dining, and discretionary spending.

The portfolio targets scale linearly. At 4%, Lean is $750k, Standard is $1.5M, and Fat is $3.0M. The arithmetic is identical; the lifestyle decision is upstream. Which tier you aim for is one of the most consequential choices in personal finance because it sets the runway. The sandbox above lets you place yourself on the spectrum and see the corresponding target without committing to any of the labels.

Where the formula understates

The single-number target is honest about what it is — a target — and dishonest about what it leaves out. Taxes: a 4% gross withdrawal from a pre-tax 401(k) is not the same as 4% of spending. If your money is mostly pre-tax, gross up the spending number by your expected retirement tax rate before applying the multiple. Healthcare: pre-Medicare healthcare can cost $10,000–$25,000 a year for a couple and belongs in the spending number, not handled as an afterthought. Lifestyle creep: today's spending number is rarely the spending number you arrive at in fifteen years. Build in honest cushion.

The largest omission is sequence risk. A 4% withdrawal works in most decades and fails in the worst ones — the retiree who started in early 2000 or in 1966 spent a decade watching their portfolio shrink while withdrawing from it. A single-number target cannot capture this. The Monte Carlo engine in the full simulator runs your withdrawal across thousands of randomized market histories and reports the probability that your target actually holds; the deterministic target on this page tells you where to aim, and Monte Carlo tells you how forgiving the aim needs to be.

What to do today

1. Write down your spending number. Not last year's spending — your projected retirement spending. Mortgage gone? Kids independent? Healthcare added? The honest number is rarely the same as last year's bank statements.

2. Pick a withdrawal rate you can defend. 4% is the default for a reason; if you choose otherwise, be able to explain why. Longer horizon, conservative temperament, or a desire to never see the portfolio shrink all argue for 3.25–3.5%.

3. Compare to your current portfolio. The chip above the chart shows the progress percentage and the remaining gap. This is the first time many people see the number written out, and the reaction is almost always either "less than I thought" or "more than I thought" — both of which are useful signals.

Where to go from here

The number is the target; getting there is the rest of the journey. The Compounding Engine covers the savings-rate math that closes the gap. The Coast FIRE Checkpoint identifies the moment your portfolio will grow into the target on its own. The Drawdown Stress Test covers what happens after you hit the target — when the portfolio has to actually support the spending. And the full simulator stitches them together: accumulation, milestones, and drawdown, modeled year-by-year against your specific plan.