How do I calculate my FIRE number?

Divide annual retirement spending by your chosen withdrawal rate. At 4%, FIRE number = spending × 25. At 3.5%, multiply by about 28.6; at 3%, multiply by about 33.3.

Is the 4% rule safe for early retirement?

The 4% starting point comes from historical U.S. research on multi-decade retirements. It is not a guarantee, especially for 40–50+ year early-retirement horizons. Many planners prefer 3–3.5% for longer plans. Pair this calculator with the SWR deep-dive guide.

What is Lean, Regular, and Fat FIRE?

They are informal spending labels, not academic categories. RetireFire’s example presets use about $40k / $60k / $100k annual spending — always substitute your real expenses, including healthcare.

Does the FIRE number include taxes and fees?

No. This is a pre-tax planning illustration. Effective after-tax spending needs, investment fees, and account types can require a larger portfolio than the simple formula suggests.

How should I stress-test my FIRE number?

Re-run at lower withdrawal rates and higher spending, compare Lean/Regular/Fat lifestyle bands, then use Years and Coast tools under the same shared assumptions. Sequence stress tests on Coast/Years show accumulation path ranges — not a full withdrawal backtest.

FIRE Number Calculator

Estimate the invested portfolio that can support your lifestyle at a chosen withdrawal rate. Defaults follow classic 4% / 25× math — fully adjustable.

Results below are educational illustrations under stated assumptions — not forecasts.

Methodology Disclaimer

Shared assumptions

One set of inputs powers every calculator. Changes sync to the URL for easy sharing. Export CSV for your notes (educational only).

Annual spending

Target lifestyle spend in today's dollars

Current portfolio

Annual contributions

Withdrawal rate4.0%

Expected real return5.0%

After inflation (today's dollars)

Return mode

Switch to Nominal to enter pre-inflation returns and set an inflation assumption.

FIRE Number Calculator

Portfolio size needed so a safe withdrawal covers annual spending. Presets are starting points — edit freely.

Core

Annual spending (today’s dollars)

Include housing, food, healthcare, travel, taxes, and fun.

Your FIRE number

$1,500,000

Portfolio multiple

25.0×

Monthly spend

$5,000

Sensitivity — withdrawal rate

Same spending ($60,000). Tap to apply to shared assumptions.

Formula: FIRE = annual spending ÷ withdrawal rate. At 4.0%, you need roughly 25.0× annual spending. Educational estimate — not advice. Methodology.

Savings rate → years to FIRE

Holding spending and your current portfolio fixed, higher savings rates (from higher income) shrink the timeline. Your approx. rate right now: 33.3%.

Table

Target: $1,500,000 · Return: 5.0% real · Withdrawal: 4.0%

Savings rate	Annual save	Years to FIRE
5%	$3,158	40.8
10%	$6,667	35.9
15%	$10,588	31.9
20%	$15,000	28.4
25%	$20,000	25.4
30%~ you	$25,714	22.7
40%	$40,000	18.1
50%	$60,000	14.2
60%	$90,000	10.8
70%	$140,000	7.7
75%	$180,000	6.3
80%	$240,000	4.9

Income is implied as spending ÷ (1 − savings rate) so lifestyle spend stays constant across rows. Starting portfolio is included. Not a personal plan.

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Ways a plan can miss

The numbers above are illustrations under stated assumptions. These six gaps are common reasons a tidy multiple does not hold up in life. Read the methodology and disclaimer.

HealthcareWatch item
Premiums, deductibles, and the years before Medicare are outside the simple FIRE multiple.
Healthcare before Medicare
HousingWatch item
Rent, insurance, maintenance, and location can move spending more than the withdrawal-rate nickname.
Budget and lifestyle notes
Sequence of returnsWatch item
The same long-run average can fail if poor markets arrive early in withdrawals.
Sequence-risk guide
TaxesWatch item
These tools illustrate pre-tax planning math. Account types and later withdrawals can raise the cash you need.
IRS Publication 590-A
LongevityWatch item
A longer retirement needs more years of spending than a 30-year historical rule of thumb.
SSA delayed retirement
LifestyleWatch item
Travel, family support, and spending creep change the target. Revisit the number when life changes.
Lean / Regular / Fat examples

How this fire number calculator works

Your FIRE number is the portfolio size that, at a chosen safe withdrawal rate (SWR), is meant to support a given annual spend without a traditional paycheck.

The classic starting point is the “4% rule” lineage (Bengen / Trinity Study): spending ÷ 0.04 equals 25× annual spending. Early retirees often stress-test 3–3.5% instead.

Use Lean, Regular, or Fat presets as starting spending levels, then replace them with your real budget. Taxes, healthcare, and housing usually matter more than the nickname.

Formula

FIRE number = Annual spending ÷ Withdrawal rate
Multiplier  = 1 ÷ Withdrawal rate

Example (4%): $60,000 ÷ 0.04 = $1,500,000 (25×)

Example: $60,000 spending at 4%

If you expect to spend $60,000 per year in retirement (today’s dollars) and use a 4% withdrawal rate, the FIRE number is $1,500,000.

At 3.5%, the same lifestyle needs about $1,714,000. At 3%, it needs $2,000,000. Lower rates buy more buffer for long early-retirement horizons and sequence-of-returns risk — at the cost of a larger nest egg.

When to use it

You want a clear portfolio target before modeling years-to-FIRE or savings rates.
You are comparing Lean vs Regular vs Fat lifestyle assumptions.
You want to stress-test 3%, 3.5%, and 4% withdrawal rates side by side.

Limitations

Illustrative only — not a guarantee markets will support a constant withdrawal rate for decades.
Does not model taxes, fees, Social Security, pensions, or home equity.
Spending often changes in retirement; revisit the number as your budget evolves.

Related guides & tools

FAQ

How do I calculate my FIRE number?: Divide annual retirement spending by your chosen withdrawal rate. At 4%, FIRE number = spending × 25. At 3.5%, multiply by about 28.6; at 3%, multiply by about 33.3.
Is the 4% rule safe for early retirement?: The 4% starting point comes from historical U.S. research on multi-decade retirements. It is not a guarantee, especially for 40–50+ year early-retirement horizons. Many planners prefer 3–3.5% for longer plans. Pair this calculator with the SWR deep-dive guide.
What is Lean, Regular, and Fat FIRE?: They are informal spending labels, not academic categories. RetireFire’s example presets use about $40k / $60k / $100k annual spending — always substitute your real expenses, including healthcare.
Does the FIRE number include taxes and fees?: No. This is a pre-tax planning illustration. Effective after-tax spending needs, investment fees, and account types can require a larger portfolio than the simple formula suggests.
How should I stress-test my FIRE number?: Re-run at lower withdrawal rates and higher spending, compare Lean/Regular/Fat lifestyle bands, then use Years and Coast tools under the same shared assumptions. Sequence stress tests on Coast/Years show accumulation path ranges — not a full withdrawal backtest.

Educational illustration only — not financial, investment, tax, or legal advice. Full disclaimer.

Methodology · Disclaimer · FAQ