Simple FIRE Calculator: How Much Do I Need to Retire?
Multiply what you spend in a year by 25. That is your starting number: this tool shows the arithmetic behind it.
- One honest number: your FIRE target from the only input that really drives it: yearly spending.
- The withdrawal rate is yours to set: move it and watch 25x become 33x or 20x in real time.
- When you get there: a projection of your savings against that target, year by year.
- Nothing hidden: every step of the math is on this page, and nothing leaves your browser.
How this calculator works & its assumptions
The calculator does two things. It turns your monthly spending into a FIRE number by dividing your yearly spending by the withdrawal rate you choose, and it grows your current net worth forward one year at a time, adding the gap between your income and expenses, then applying your expected return, until it crosses that number. The age where the two lines meet is your estimated FIRE age.
- Your FIRE number is annual spending divided by your withdrawal rate: at a 4% rate that is the familiar 25x multiple.
- Market returns are entered after inflation (a real return), so every figure is in today’s dollars and needs no separate inflation adjustment.
- The same return is applied every year; real markets vary widely from one year to the next.
- You save the gap between your income and expenses each month, and that gap stays constant.
- Taxes, pensions, state benefits, and one-off windfalls are all excluded.
Every data source, formula and default across this site is documented on the methodology page.
This calculator is for educational purposes only. Consult a qualified financial professional for advice specific to your situation.
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Results
FIRE Target: $900K
FIRE Age: 47
FIRE Year:
Saving 40% of take-home
Current Age
30 years
Current Net Worth
$100K
Monthly Income (After Taxes)
$5K
Monthly Expenses
$3K
Market Returns (real, inflation-adjusted)
6%
Safe Withdrawal Rate
4%
Net Worth Projection
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Understanding the Calculator
Market Returns
A real return is the growth left over once inflation is taken out. If a portfolio gains 9% in a year and prices rise 3%, you end the year roughly 6% richer in things you can actually buy. That 6% is the real return, and it is the figure this slider takes.
The headline returns you see quoted are usually nominal, meaning inflation is still inside them. Entering one of those here would make the plan look faster than it is, because nothing in this calculator ever takes inflation back out.
Nothing here inflates, by design. Your spending, your saving and your target all stay fixed in today's money, so a target of $900,000 means what that buys today, not the larger sticker price it would carry decades from now. It also means a raise that only keeps pace with prices does nothing here.
A 6% real return approximates the long-term historical average for a diversified stock portfolio (the S&P 500, after inflation), which is why this calculator defaults to it. Actual returns will vary year to year.
Safe Withdrawal Rate (SWR)
The SWR is how much you can safely withdraw from your portfolio each year in retirement. The traditional 4% rule suggests you can withdraw 4% of your initial portfolio value annually, adjusted for inflation, with a high probability of your money lasting 30+ years. A lower rate is more conservative, while a higher rate is more aggressive.
FIRE Target
Your FIRE target is calculated as: (Monthly Expenses × 12) ÷ SWR. For example, with $3,000 monthly expenses and 4% SWR, you'd need $900,000 ($36,000 ÷ 0.04) to reach financial independence. This is also known as your "FI number" or "retirement number".
How much do I need to retire?
Take what you expect to spend in a year and divide it by the withdrawal rate you plan to use. At a 4% withdrawal rate that division is the same as multiplying by 25, which is why you hear the FIRE number called the 25x rule. It depends on what you spend rather than what you earn: two people on very different salaries who spend the same amount need the same portfolio.
Worked through with this calculator's default values:
- Start with monthly spending of $3,000.
- Multiply by 12 to get yearly spending: $36,000.
- Divide by the withdrawal rate (4%), the same as multiplying by 25.
- Your FIRE number is $900,000.
That is the whole calculation. Change the spending slider and the target moves with it; every dollar of yearly spending you can permanently avoid removes 25 dollars from the amount you need to save.
This number is a target, not a timeline. For how long reaching it takes at your current saving rate, the savings rate calculator turns that rate into years, and for the balance that would grow into it on its own without saving another dollar, the coast FIRE calculator works out when you could stop.
Why your withdrawal rate is the whole ballgame
Because the target is a division, the withdrawal rate you pick moves it more than any other choice you make. Dropping from 4% to 3% makes your goal a third bigger. Here is the same yearly spending of $36,000 run at three common rates:
| Withdrawal rate | Multiple of yearly spending | FIRE number |
|---|---|---|
| 3% | 33.3x | $1,200,000 |
| 4% | 25x | $900,000 |
| 5% | 20x | $720,000 |
A lower rate buys safety and costs years of saving; a higher rate does the reverse. Which one is right depends on how long your money has to last and how willing you are to adjust your spending if markets disappoint, neither of which this quick estimate can see.
What this quick estimate deliberately ignores
Four things, all of them on purpose. A first number is more useful when it is simple enough to check by hand, so this tool leaves out the complications below, but you should know they exist before you treat the result as a plan.
- Taxes: Withdrawals are treated as if they land in your pocket whole. In reality the account a dollar sits in changes what you keep, and your spending figure should be what you need after tax. If your withdrawals will be taxed, raise that figure accordingly, or use the full planner, which models a withdrawal tax rate directly.
- Sequence-of-returns risk: This tool grows your portfolio by the same return every single year. Real markets do not, and the ORDER of returns matters enormously: a bad run in the first few years of retirement does far more damage than the same run twenty years in, because you are selling while prices are down. A single average return cannot show you that risk.
- Variable spending: Your spending is assumed flat forever. Most real retirements are not: there are mortgage payoffs, children leaving home, an expensive early travel phase, and later care costs. Flat spending is a reasonable first approximation, not a forecast.
- Pensions and state benefits: No pension, social security, annuity, or other future income stream is counted. Any of them reduces what your portfolio has to cover, so treating them as zero makes this estimate deliberately conservative.
When the quick number stops being enough, there are two next steps on this site. The full FIRE plan calculator adds taxes, housing equity and a year-by-year projection of your actual finances. The historical FIRE simulator replays your plan against more than 150 years of real market history, which is the only honest way to see sequence-of-returns risk rather than assume it away.
Frequently asked questions
How much do I need to retire?
Divide the amount you expect to spend in a year by your withdrawal rate. At a 4% withdrawal rate that is the same as multiplying annual spending by 25, so $36,000 a year needs about $900,000. That is your FIRE number: the invested capital whose withdrawals cover your spending indefinitely. It depends on what you spend, not on what you earn.
Is the 4% rule still valid?
It is a useful starting point, not a law. The 4% rule came from studying historical US market returns over 30-year retirements, and the mechanism it rests on, that a diversified portfolio has usually grown faster than a 4% withdrawal drains it, has not changed. What the rule cannot tell you is whether YOUR retirement lands on a good or a bad stretch of market history, which matters more the earlier you retire and the longer your money has to last. Backtest a plan against real historical sequences rather than trusting a single average.
Does this include my pension or social security?
No. This calculator assumes your portfolio covers all of your spending on its own, which makes the target deliberately conservative. Any pension, state benefit, or annuity income reduces what your portfolio must cover: subtract that expected annual income from your annual spending first, then divide what is left by your withdrawal rate.
How much do I need to retire at 40?
The target itself does not change with age: it is still annual spending divided by your withdrawal rate. What changes is the margin for error. Retiring at 40 means funding perhaps fifty years instead of thirty, so the same portfolio has to survive far more market cycles, and many early retirees choose a lower withdrawal rate to compensate. Move the withdrawal rate slider down and watch the target rise to see exactly what that caution costs.
What withdrawal rate should I use?
Lower means safer and slower. The rate is simply the share of your portfolio you plan to spend each year, and it drives the target more than any other input: every percentage point you drop makes the number you are saving toward meaningfully larger. Longer retirements, lower risk tolerance, and no willingness to earn again later all argue for a lower rate.
Does this account for inflation?
Yes, by working entirely in today’s dollars. You enter the market return you expect AFTER inflation, a real return, so the FIRE number this produces is already in money you can compare to today’s prices. There is no separate inflation setting to tune, and no scary-looking future figure to mentally discount.
Is my data stored anywhere?
No. Everything runs in your browser. There is no account and no server: the only place your inputs go is your own browser’s local storage, and only if you choose to save them. Close the tab and nothing follows you.