What is a Coast FIRE number?

It is the portfolio today that may grow to your full FIRE number by a chosen traditional retirement age without additional contributions, under an assumed real return.

Does Coast FIRE mean I can quit my job?

Usually no. Coast FIRE means you may not need aggressive retirement contributions anymore. You typically still work to cover living expenses until full FIRE or another income plan.

How is Coast FIRE different from Barista FIRE?

Coast focuses on stopping contributions while still working full-time (or not). Barista FIRE uses ongoing part-time income to shrink the portfolio needed to cover spending.

Do you include a sequence-of-returns stress test?

Yes — a free basic Monte Carlo stress test (1,000 paths) is available on the Coast FIRE calculator. It is educational, not a forecast or historical backtest. See Methodology and the how-to stress-test guide.

When can I stop saving for retirement?

Under Coast math, when portfolio ≥ coast number and life gates pass (healthcare, emergency fund, partner alignment, stress cases). Prefer keeping a savings floor and re-running after major life changes. Use the free Coast checklist.

Why does a lower assumed return raise my coast number?

Coast discounts full FIRE over n years at rate r. Lower r means less expected compounding, so you need more capital today for the same future target. Stress-test 4% real if your base case is 5%.

Coast FIRE Calculator

Calculate how much you need today so compound growth alone may reach full FIRE by a chosen traditional retirement age — then you can “coast” on savings rate.

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.

Coast FIRE Calculator

Nest egg that can grow — with no further contributions — to full FIRE by a traditional retirement age. Then you can stop aggressively saving.

Building

Current age

Traditional retirement age

Horizon for full FIRE if you stop saving after Coast.

Coast number (today)

$271,935

Full FIRE number

$1,500,000

Shortfall to coast

$121,935

At retirement if you stop now

$827,402

You need about $121,935 more invested to hit your coast number. Once there, growth alone for 35 years is modeled to reach full FIRE ($1,500,000) by age 65. With zero new savings, current assets alone would take roughly 12.2 years to reach the coast number.

Formula: coast = FIRE ÷ (1 + r)^years. Coast FIRE means you could stop saving — not that early retirement is funded yet. Educational only.

Sensitivity — real return

Coast number for full FIRE $1,500,000 by age 65. Lower r raises today's bar.

Coast FIRE by age

Full FIRE $1,500,000 by age 65. Primary r = 5.0%; stress column at 4.0%. Educational only.

Age	Years	Coast @ 5%	Coast @ 4%
25	40	$213,069	$312,434
30near you	35	$271,935	$380,123
35	30	$347,066	$462,478
40	25	$442,954	$562,675
45	20	$565,334	$684,580
50	15	$721,526	$832,897
55	10	$920,870	$1,013,346

Formula: coast = FIRE ÷ (1+r)^years. Not early retirement funding. Sequence risk is not in this table — use the stress test below.

The main calculators assume a smooth return every year. Markets bounce. This stress test runs 1,000 random paths with the same average real return and a fixed volatility, then shows how often terminal wealth meets Full FIRE under a simple definition.

Volatility (illustrative)

Free1,000 paths · success rate · p10/p50/p90 · stays freeComing Pro5,000+ paths, regimes, historical engines (planned)See Pro

Success rate

13%

132 / 1,000 paths ≥ target

p10 terminal

$185,317

Lower tail (illustrative)

Median terminal

$594,087

p50 of simulated endings

p90 terminal

$1,685,316

Upper tail (illustrative)

Sample paths (worst / median / best by terminal)

Terminal wealth distribution

Model: independent annual shocks r = 5.0% ± σ·Z (Z standard normal), end-of-year contributions, seed 42 for reproducibility. Mean return 5.0%, σ 15.0%, horizon 35 years, 1,000 paths. Not historical backtesting, not tax-aware, not advice. Details: Methodology · Approach.

Historical retirement scenarios

Data gate

Historical scenarios are unavailable until the source data is independently verified.

Production historical results remain disabled until the submitted series can be independently reproduced from a documented source, transformation method, coverage, and checksum.

Historical scenarios are not future probabilities. See the methodology for the data and calculation limits.

Loading calculators…

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 coast fire calculator works

Coast FIRE asks a different question than classic FIRE: do you already have enough invested that, with no further contributions, compound growth may reach full FIRE by a traditional retirement age?

If yes, you might stop aggressive saving (or save only for near-term goals) while still working for lifestyle, purpose, or benefits. Coast FIRE is not permission to stop working tomorrow.

The coast number is essentially a discounted full FIRE target: the longer the runway and the higher the assumed real return, the smaller the nest egg you need today.

Formula

Coast number ≈ Full FIRE ÷ (1 + r)^n

T = full FIRE target
r = real return
n = years until traditional retirement age

Example: $1.5M full FIRE, 20 years runway, 5% real

If full FIRE is $1,500,000, traditional retirement is 20 years away, and you assume 5% real growth, coast number ≈ $1,500,000 ÷ (1.05)^20 ≈ $565,000.

With about $565k invested today and no further contributions (under those assumptions), the model says the portfolio could grow to the full target by traditional retirement age.

When to use it

You want to know when aggressive saving can slow without abandoning long-term FI.
You are comparing shortfall vs surplus under conservative return assumptions.
You are planning a “work optional later, not unemployed today” path.

Limitations

Not early retirement — coasters usually still need earned income for years.
Healthcare, emergency funds, and debt plans still matter.
Constant real returns are not guaranteed; use return sensitivity, age tables, and the free sequence stress test for ranges.

Related guides & tools

FAQ

What is a Coast FIRE number?: It is the portfolio today that may grow to your full FIRE number by a chosen traditional retirement age without additional contributions, under an assumed real return.
Does Coast FIRE mean I can quit my job?: Usually no. Coast FIRE means you may not need aggressive retirement contributions anymore. You typically still work to cover living expenses until full FIRE or another income plan.
How is Coast FIRE different from Barista FIRE?: Coast focuses on stopping contributions while still working full-time (or not). Barista FIRE uses ongoing part-time income to shrink the portfolio needed to cover spending.
Do you include a sequence-of-returns stress test?: Yes — a free basic Monte Carlo stress test (1,000 paths) is available on the Coast FIRE calculator. It is educational, not a forecast or historical backtest. See Methodology and the how-to stress-test guide.
When can I stop saving for retirement?: Under Coast math, when portfolio ≥ coast number and life gates pass (healthcare, emergency fund, partner alignment, stress cases). Prefer keeping a savings floor and re-running after major life changes. Use the free Coast checklist.
Why does a lower assumed return raise my coast number?: Coast discounts full FIRE over n years at rate r. Lower r means less expected compounding, so you need more capital today for the same future target. Stress-test 4% real if your base case is 5%.

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

Methodology · Disclaimer · FAQ