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FIRE Number Calculator: What Is Your FIRE Number, and Will You Reach It in Time?

How much do you need invested before work becomes a choice? That amount is your FIRE number. Type what you plan to spend in retirement, what you have invested today, and what you add each month, and this page reads you your FIRE number, the pot your current path builds by your target age, and the age your pot crosses the line. The math runs in your browser; the numbers you type are never sent to us.

Your numbers

You and your retirement

Your current age

Age you want to reach your FIRE number

Your current age has to be younger than your target age: the years between them are the years your path gets to grow.

Your money

Yearly spending in retirement ($)

What a year of your retired life costs, in today's dollars. A rough figure is fine; you can test a leaner and a fuller one.

Invested today ($)

Everything you have invested for retirement, added together. Zero is an honest answer if you are starting now.

What you add, and your assumptions

Monthly contribution ($)

What you add to your investments each month. Zero is an honest answer if you are not adding right now.

Yearly return (%)

Your assumption, not a forecast and not a promise. Past returns do not guarantee future ones, so test a careful figure too.

Withdrawal rate (%)

The standard is 4 percent, a rule of thumb, not a promise. You can set it from 2 to 6 percent and watch the answer move.

Your FIRE number Your number is waiting

Type your numbers above to see your FIRE number.

Pot at your target age $0 What your current path builds by your target age.

Invested today $0 The pot this calculation starts from.

Still to go at target age $0 The distance between your pot at target age and your FIRE number.

Crossing age 0 The age your pot reaches your FIRE number on this path.

Years to target age 0 years From your current age to your target age.

FIRE number = yearly spending divided by withdrawal rate. Pot at target age = what you have, grown at your return, plus each year of monthly savings grown the same way.

The formula in plain words: your FIRE number sizes the whole pot from your yearly spending. Your path then has two engines: the money already invested, growing every year, and the money you add each month, grouped into a year of savings at a time and grown the same way. This page adds both engines up at your target age and compares the total with the number.

Picture the morning your pot reaches this number: work becomes a choice, not a bill.

What this free calculator did not calculate. No year-by-year table: this page gives you the headline numbers for one path, not a year-by-year path. No Lean, Standard, Fat, Coast, or Barista tiers: one spending figure in, one FIRE number out. No what-if moves: it does not test saving more, spending less, or retiring later side by side. No taxes or investment fees. No inflation split: spending and returns are both in today's dollars, the simple standard way. The paid FIRE spreadsheet runs the full picture: your FIRE number, your years to freedom, your progress across all five tiers, and a savings engine that tests five what-if moves and names the lever that buys you the most time.

Take your FIRE number with you

Your FIRE number is above, and it is yours to keep. Join KOLLAZ Modern Money for one plain-number email a week, and get the free Know Your Date sheet as a welcome gift.

How the FIRE number calculator works

Updated November 2026

What a FIRE number is

FIRE stands for financial independence, retire early. Your FIRE number is the size of the pot that makes work a choice: once your investments reach it, your yearly spending in retirement can come out of the pot year after year, at the withdrawal rate you set. It is not a retirement date and it is not a promise. It is a target with a dollar figure on it, which is what makes it useful.

The formula, in plain words and symbols

Three steps, and the calculator above runs exactly these:

Step 1: your FIRE number. FIRE number = yearly spending in retirement / (withdrawal rate / 100). At the standard 4 percent rule of thumb, that is your yearly spending divided by 0.04, which is 25 times your yearly spending. The 4 percent figure is a rule of thumb, stated openly, not a promise.

Step 2: grow what you have. The money you have invested today grows at your assumed return for every year until your target age: invested today x (1 + return / 100) ^ years. At a 7 percent return over 20 years, the growth factor is about 3.87: a dollar invested today becomes about $3.87, if that return actually happens every year, which real markets never do so smoothly.

Step 3: grow what you add. Your monthly contribution is grouped into a year of savings at a time, added at the end of each year and grown at the same return. The two grown amounts added together are your pot at your target age. If that pot is at or past your FIRE number, your current path reaches it in time. If it falls short, the gap is the distance, and the crossing age tells you when this path gets there if you keep going past the target age.

A worked example

Take the numbers this calculator opens with. Age 35, aiming at 55, planning to spend $60,000 a year in retirement, with $100,000 invested today and $1,000 added each month, at a 7 percent return and the standard 4 percent withdrawal rate.

Step 1: $60,000 / 0.04 gives a FIRE number of $1,500,000.00. Step 2: the $100,000 grows by a factor of about 3.87 over 20 years, to about $386,968. Step 3: the $1,000 a month, a year of savings at a time, grows to about $491,946. Together the pot at age 55 is $878,914.35, which leaves a gap of $621,085.65 at the target age. Keep the same path going and the pot crosses $1,500,000.00 at age 61.9, about seven years late. That is an honest answer, and it points at the levers: more added each month, a later target age, or lower spending in retirement each move the crossing age. Change any one input above and every one of those numbers moves; that is what the fields are for.

How to read your result

Your FIRE number is the headline: the full target, sized from your spending. The pot at your target age is what your current path actually builds. The gap is the distance between the two at the age you picked, and the crossing age is the same story told as an age: when this path reaches the full number if nothing changes. Test a lower return before you trust a cheerful answer; a plan that only works at a high return is not a safe plan.

What the math takes as given, and what it leaves out

The math holds your return steady every year, which real markets never do, and it works in today's dollars, with no split for inflation. It leaves out taxes, investment fees, pensions and government benefits. It runs one path only: it does not compare saving more against spending less or retiring later. It is a headline check, priced honestly: it tells you the size of the target and whether this path reaches it, not what every year between here and retirement will look like.

The coast point on the same road

Your FIRE number is where the road ends. Partway along it sits a quieter milestone: the point where the money you have already invested would grow into the full number on its own, even if you stopped adding. That milestone has its own math, and the Kollaz Money guide Coast FIRE Calculator: Could You Stop Saving for Retirement Today? walks through it with worked dollar figures.

Sources

The method is the standard FIRE number definition: the full pot sized from yearly spending and the withdrawal rate, tested against a path of growth plus steady contributions. It is the same starting point the paid workbook builds on: FIRE Calculator Spreadsheet (Kollaz, KM-011), which adds the five tiers and the what-if savings engine.
The 4 percent figure is a rule of thumb for sizing a retirement pot, labelled as one everywhere on this page. It is not a guarantee, and this calculator lets you replace it with any rate from 2 to 6 percent.

Educational information only, not financial advice. Consider a qualified professional for decisions about your specific situation.

Frequently asked questions

What is a FIRE number?

Your FIRE number is the total amount you need invested so that your yearly spending in retirement can come out of the pot year after year. This page works it out from the yearly spending you type in and your withdrawal rate. It is a target to aim at, not a promise about any market.

How is the FIRE number worked out?

Two steps. First, your FIRE number is your yearly spending in retirement divided by your withdrawal rate: at the standard 4 percent, that is 25 times your yearly spending. Second, this page grows the money you have today, plus the amount you add each month, at your assumed return, and checks whether the pot reaches that number by your target age, and at what age it crosses.

What return should I assume?

That is your call, and this page treats it as your assumption, never as a forecast. The return field is editable so you can test a careful figure and a hopeful one and watch the answer move. Past returns are not a promise of future returns, and a plan that only works at a high return is a plan that needs more saving, not more hope.

What does the 4 percent rule mean?

It is a rule of thumb that says a retirement pot can pay out about 4 percent of its value per year. Turned around, it sizes the pot: yearly spending divided by 4 percent gives a FIRE number 25 times your yearly spending. It is a rough guide, not a promise and not a guarantee. This calculator lets you set the rate from 2 to 6 percent so you can see how much the answer moves.

Where does my information go when I use this calculator?

The calculation runs entirely in your browser on your own device, and the numbers you type are never sent to us or stored. Like every Kollaz page, this one counts visits with cookies only if you accept them; the consent banner explains that choice, and it is yours to decline. The signup form on this page sends only the email address you type into it, and your first name if you add it, when you press its button. Signing up takes one more step: we email you a link, and clicking it is what subscribes you.

Is this financial advice?

No. It is arithmetic on the numbers you type, using the standard FIRE number formula. It does not know your debts, your health, your pension, or your life. For decisions about your specific situation, talk to a qualified professional.