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FIRE Number Calculator25x Rule · Financial Independence Target

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The FIRE number calculator instantly tells you the total investment portfolio you need to achieve financial independence. Enter your expected annual expenses in retirement and your chosen withdrawal rate to calculate your exact FIRE number using the proven 4% rule - a single number that represents complete financial freedom.

All calculations use standard published formulas. Results are for informational use only.

FIRE Number Details

Expense entry

Annual expenses ($)

Withdrawal rate (%)

To retire on $50,000 per year at a 4.0% withdrawal rate, you need a total investment portfolio of $1,250,000 - equivalent to 25.0x your annual spending. This portfolio generates approximately $4,167 per month in passive income at your chosen withdrawal rate.

FIRE number

$1,250,000

25.0x your annual spending

$50,000

Annual expenses

25.0x

Multiplier

$4,167

Monthly passive income

Annual Expenses 4.0%Remaining Portfolio 96.0%

Getting started

How to Use This FIRE Number Calculator

Enter your expected retirement expenses

Choose whether you want to enter monthly or annual expenses, then provide the total amount you expect to spend per year once you stop working.

Select your withdrawal rate

The default 4% is based on the Trinity Study. Lower rates are more conservative for longer retirements. Adjust the rate to see how it impacts your goal.

Read your results

Your FIRE number appears instantly, along with the portfolio multiplier and estimated monthly passive income it would generate.

Definitions

What is a FIRE Number?

Your FIRE number is the total value of your investment portfolio at which point you are financially independent - meaning your portfolio can generate enough passive income through dividends, interest, and capital appreciation to cover all of your living expenses indefinitely, without needing to work.

The concept comes from the 4% rule, popularised by financial researchers William Bengen (1994) and the Trinity Study (1998). The research found that withdrawing 4% of an initial portfolio value annually - adjusted upward for inflation each year - had historically survived 30-year retirements with a success rate above 95% using a diversified US stock and bond portfolio.

The 4% rule converts to a simple shortcut: your FIRE number equals 25 times your annual spending. If you expect to spend $60,000 per year in retirement, your FIRE number is $1,500,000.

The calculation

FIRE Number Formula

Identify Annual Expenses and Withdrawal Rate

Expenses = $60,000 Withdrawal Rate (WR) = 4% (0.04)

Divide Expenses by WR

FIRE Number = Annual Expenses ÷ WR FIRE Number = $60,000 ÷ 0.04

FIRE Number = $1,500,000

Shortcut: The Multiplier Method

Multiplier = 100 ÷ WR At 4% WR: Multiplier = 100 ÷ 4 = 25 FIRE Number = $60,000 × 25

FIRE Number = $1,500,000

FIRE number at common spending levels

Annual spending	3% WR	3.5% WR	4% WR	5% WR
$25,000	$833,333	$714,286	$625,000	$500,000
$35,000	$1,166,667	$1,000,000	$875,000	$700,000
$50,000	$1,666,667	$1,428,571	$1,250,000	$1,000,000
$60,000	$2,000,000	$1,714,286	$1,500,000	$1,200,000
$75,000	$2,500,000	$2,142,857	$1,875,000	$1,500,000
$100,000	$3,333,333	$2,857,143	$2,500,000	$2,000,000

Examples

Real-Life FIRE Number Examples

Lean FIRE

$35,000/year

$35K expenses · 4% WR

$875,000

Monthly passive income: $2,917

Regular FIRE

$55,000/year

$55K expenses · 3.5% WR

$1,571,429

Monthly passive income: $4,583

Fat FIRE

$120,000/year

$120K expenses · 3.5% WR

$3,428,571

Monthly passive income: $10,000

Analysis

Choosing the Right Withdrawal Rate

Your withdrawal rate is one of the most consequential decisions in FIRE planning. A higher withdrawal rate means a smaller FIRE number but a greater risk of running out of money - particularly over long retirements of 40-50+ years.

Withdrawal Rate	Multiplier	Best For
3.0%	33.3x	Very early retirement (20s-30s); maximum safety margin.
3.5%	28.6x	Early retirement (30s-40s); conservative long-horizon planning.
4.0%	25x	Standard FIRE target; based on Trinity Study for 30-year retirements.
5.0%	20x	Traditional retirement (60+); shorter retirement horizon.

FAQ

Frequently asked questions

What is a FIRE number?

Your FIRE number is the total investment portfolio value you need to retire and live entirely off investment returns. It is calculated by dividing your expected annual retirement expenses by your planned withdrawal rate. At a 4% withdrawal rate your FIRE number is exactly 25 times your annual spending - for example, $50,000 in annual expenses requires a FIRE number of $1,250,000.

How do you calculate your FIRE number?

FIRE Number = Annual Expenses / Withdrawal Rate. Using the standard 4% rule: FIRE Number = Annual Expenses x 25. For a 3.5% withdrawal rate: x 28.6. For a 3% withdrawal rate: x 33.3. Enter your annual expenses and withdrawal rate into the calculator above for an instant result.

What expenses should I include in my FIRE number calculation?

Include all recurring annual expenses you expect in retirement: housing (rent, mortgage, or maintenance), food, utilities, transport, healthcare, travel, entertainment, and any subscriptions or memberships. Add a 10-15% buffer for irregular costs and consider that healthcare costs tend to rise significantly with age.

Is the 25x rule the same as the FIRE number?

Yes - the 25x rule and the FIRE number are the same concept. Multiplying annual expenses by 25 is identical to dividing by 0.04 (4%). Both give you the portfolio size at which a 4% annual withdrawal covers your expenses. The 25x shortcut is simply easier to calculate mentally.

What withdrawal rate should I use for my FIRE number?

The 4% rule is the most commonly cited starting point, based on the Trinity Study which found it sustained a 30-year retirement with a high probability of success. For early retirement (40+ year horizon), many FIRE practitioners prefer 3.5% or 3%, which increases the FIRE number but provides a larger safety margin. The lower the withdrawal rate, the more conservative and robust the plan.

Should I use pre-tax or post-tax expenses for my FIRE number?

Use your actual spending including taxes. If you plan to withdraw from a traditional 401(k) or IRA, your withdrawals will be taxed as ordinary income. Factor tax liability into your annual expenses estimate or add an additional 10-25% depending on your expected tax bracket in retirement.

Can inflation affect my FIRE number?

Yes. The standard 4% rule is designed as a real (inflation-adjusted) withdrawal, meaning withdrawals increase with inflation each year while the portfolio compounds nominally. If you use this calculator with today's expenses, the FIRE number is already expressed in real (today's dollar) terms - assuming you use a real return rate for any portfolio growth projections.

Does my FIRE number change over time?

Your FIRE number is based on your retirement expenses and withdrawal rate. If your expected lifestyle costs change - due to paying off a mortgage, adding children, relocating, or changing health needs - recalculate your FIRE number. It is worth reviewing annually as your plans become more concrete.

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