How do you calculate your FIRE number?

Divide your annual spending by your chosen safe withdrawal rate. At a 4% rate that is annual spending multiplied by 25, so $48,000 a year of spending gives a FIRE number of $1,200,000. At a 3% rate the same spending needs about $1,600,000.

Why is the FIRE number based on spending rather than income?

Because the portfolio has to replace what you spend, not what you earn. Two people on very different salaries who spend the same amount have the same FIRE number; the higher earner simply reaches it sooner.

Where does the 25× rule come from?

It is the arithmetic inverse of a 4% withdrawal rate, which was popularised by the 1998 Trinity Study of historical US portfolio survival over thirty-year retirements. The multiplier is arithmetic and exact; the 4% figure it rests on is an empirical result about one country's past with well-known limitations.

Should your house count toward your FIRE number?

Generally not on the asset side, because you cannot withdraw 4% a year from a house you live in. Owning it outright reduces the spending the number has to cover, which lowers the target from the other direction.

What return should you assume?

Use a real return — after inflation — so the target stays in today's money. Anything you assume is a guess about the future; the honest use of this calculator is to try several and see how much the answer moves, which is usually more than people expect.

selftickr

FIRE number calculator

Last checked 3 September 2026

The portfolio that would cover your spending, and roughly how long it takes to build. Every assumption is adjustable, because every one of them is a guess.

Annual spendingWhat you spend in a year, not what you earn.Already investedInvested assets only.Saving per yearContributions, not returns.

Withdrawal rate

Assumed return after inflation: 5.0%Real, not nominal — so the target below is in today’s money and does not need adjusting for inflation later.

Runs entirely in your browser. Nothing you type is sent to selftickr or stored.

What is a FIRE number?

A FIRE number is the size of invested portfolio at which its expected withdrawals would cover your annual spending indefinitely, calculated as annual spending divided by a chosen safe withdrawal rate — most commonly 4%, which is the same as multiplying spending by 25.

FIRE number

annual spending ÷ withdrawal rate

At 4% this is annual spending × 25. At 3%, × 33. At 5%, × 20.

The number is driven entirely by spending. Somebody who spends $40,000 a year needs $1,000,000 at a 4% rate whether they earn $60,000 or $600,000 — the higher earner just gets there faster. This is why reducing a recurring cost does double work: it raises what you can save and lowers the target at the same time.

What the same spending needs at different rates

Annual spending	At 5%	At 4%	At 3%
$30,000	$600,000	$750,000	$1,000,000
$48,000	$960,000	$1,200,000	$1,600,000
$75,000	$1,500,000	$1,875,000	$2,500,000
$120,000	$2,400,000	$3,000,000	$4,000,000

The spread across that row is the honest headline. Moving from a 4% assumption to a 3% one raises the target by a third, and neither is a fact — they are positions on how much uncertainty you want to absorb in advance.

What this calculator will not tell you

It does not quote a success probability, and that is deliberate. The Trinity Study’s table of survival rates is among the most reproduced sets of numbers in personal finance and among the least often checked against the original article. Repeating it here on trust, on a page whose whole claim is that its figures are sourced, would undermine the point of the page.

Three things move the real answer more than the arithmetic does. Sequence of returns — a poor first few years of retirement does far more damage than the same years later, because withdrawals lock the losses in. Retirement length — a fifty-year early retirement is a materially harder problem than the thirty-year one the 4% figure was derived from. And flexibility — being willing to spend less in bad years does more for a portfolio’s survival than choosing a lower starting rate and never revisiting it.

It also ignores state pensions, future inheritance, part-time income, healthcare costs and tax, any of which can move a real plan substantially in either direction.

Frequently asked questions

How do you calculate your FIRE number?: Divide your annual spending by your chosen safe withdrawal rate. At a 4% rate that is annual spending multiplied by 25, so $48,000 a year of spending gives a FIRE number of $1,200,000. At a 3% rate the same spending needs about $1,600,000.
Why is the FIRE number based on spending rather than income?: Because the portfolio has to replace what you spend, not what you earn. Two people on very different salaries who spend the same amount have the same FIRE number; the higher earner simply reaches it sooner.
Where does the 25× rule come from?: It is the arithmetic inverse of a 4% withdrawal rate, which was popularised by the 1998 Trinity Study of historical US portfolio survival over thirty-year retirements. The multiplier is arithmetic and exact; the 4% figure it rests on is an empirical result about one country's past with well-known limitations.
Should your house count toward your FIRE number?: Generally not on the asset side, because you cannot withdraw 4% a year from a house you live in. Owning it outright reduces the spending the number has to cover, which lowers the target from the other direction.
What return should you assume?: Use a real return — after inflation — so the target stays in today's money. Anything you assume is a guess about the future; the honest use of this calculator is to try several and see how much the answer moves, which is usually more than people expect.

A target is easier to hit when you can watch it move

selftickr renders your net worth as a live ticker — daily change, rating, chart — so progress toward a number like this is something you see rather than something you recalculate.

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