Time until retirementHigh modeled impact
Higher input lowers the modeled result
More time allows more assumed real compounding before retirement.
Retire · No-contribution threshold
Coast FIRE Calculator
Estimate how much invested today could grow toward a modeled retirement target if no additional contributions are made.
Educational scenario $0 future contributions Inflation-adjusted math
Your result
Coast FIRE threshold today
$344,439
The amount that could grow to this scenario’s retirement target with $0 of future contributions modeled.
$0 future contributions modeledOnly the portfolio already invested is compounded.
Years to retirement30
Real annual return4.39%
Retirement FIRE target$1,250,000
Portfolio-funded spending$50,000
Current portfolio$350,000
Projected at retirement$1,270,180
Under these assumptions, the current portfolio is about $5,561 above the modeled threshold. This does not mean future saving is unnecessary.
Current portfolio vs. threshold101.61%
Current portfolio$350,000
Threshold today$344,439
Above modeled threshold$5,561
This is a comparison with one modeled threshold, not confirmation of retirement readiness.
No-contribution growth path
Today to planned retirement
Both paths use the same constant real return and include no future contributions.
Threshold path Current portfolio path Retirement target
Threshold today$344,439
Target at retirement$1,250,000
Current portfolio projected$1,270,180
Return sensitivity
Five nominal-return scenarios
Each row keeps age, spending, other income, withdrawal rate, and inflation unchanged. A higher assumed return lowers today’s modeled threshold; no return is recommended.
5.0%
$606,662
6.0%
$456,510
7.0%Current input
$344,439
8.0%
$260,563
9.0%
$197,620
Nominal returns from 5% through 9%, adjusted for 2.5% inflation, produce different thresholds today.
Through the Lens
What drives this result?
Controlled, deterministic sensitivity around your current inputs reveals which assumptions move the Coast FIRE threshold today most.
Nominal returnHigh modeled impact
Higher input lowers the modeled result
Higher return lowers the amount modeled as necessary today.
Annual spendingHigh modeled impact
Higher input raises the modeled result
Spending not covered by other income sets the funded need.
Withdrawal rateHigh modeled impact
Higher input lowers the modeled result
A lower withdrawal assumption increases the retirement target.
InflationModerate modeled impact
Higher input raises the modeled result
Higher inflation reduces the real return and raises today’s threshold.
High modeled impact means an input changes this output substantially around the current scenario. Rankings compare controlled 10% input changes; they do not measure risk, probability, personal importance, controllability, suitability, advice, or forecasts.
Meaning
What this means
The threshold works backward from a future portfolio target.
A modeled threshold of $344,439 at age 35 is the amount that would compound for 30 years at a 4.39% real annual return to reach the $1,250,000 target at age 65.
Threshold today→Future target
The target represents $50,000 of annual portfolio-funded spending at the entered withdrawal-rate assumption.
Implication
The current $350,000 portfolio is projected to become $1,270,180 in today’s dollars if the constant return assumptions hold and no more is contributed.
This is a narrow compounding scenario. Being at or above the threshold does not remove the value of future saving, and it does not establish retirement readiness.
Methodology
How the calculator works
Years to retirement
planned retirement age − current agePortfolio-funded spending
max(annual spending − other annual income, 0)Modeled FIRE target
portfolio-funded spending ÷ (withdrawal rate ÷ 100)Exact real annual return
((1 + nominal return) ÷ (1 + inflation)) − 1Coast FIRE threshold today
FIRE target ÷ (1 + real return) ^ years to retirementCurrent portfolio at retirement
current portfolio × (1 + real return) ^ years to retirementModeled progress
current portfolio ÷ Coast FIRE threshold × 100Rates are converted to decimals before calculation. The real return is not estimated by simply subtracting inflation from the nominal return. The progress bar is visually capped at 100%, although the numerical result can be higher.
Guardrails
Assumptions and limitations
This educational scenario assumes:
- No future contributions after the current invested portfolio
- A constant annualized nominal return and constant inflation rate
- Spending and other income entered in today’s dollars
- The entered withdrawal rate remains unchanged
Actual market returns and inflation vary.
Taxes, investment fees, trading costs, sequence-of-returns risk, changes in spending or income, healthcare, longevity, and one-time expenses are excluded. Results are scenarios—not forecasts or financial advice.
Negative real-return scenarios are allowed.
When the nominal return is below inflation, purchasing power declines. The threshold today can therefore be greater than the future target.
Known-answer checks
Examples used to validate the engine
Standard caseAt ages 35 to 65, $50,000 funded spending at 4% produces a $1,250,000 target and about a $344,439 threshold.
Exact real return7% nominal and 2.5% inflation equals 4.3902439% real—not 4.5%.
Time and returnWith positive real growth, more years or a higher return lowers the amount required today.
Income covers spendingIf other income covers spending, the portfolio-funded target and Coast threshold are $0 without making a readiness claim.
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