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Coast FIRE Calculator

Find the invested amount that could grow to your retirement target without any more contributions — then test whether your current plan gets there.

Published by GrowThenDraw Editorial Team · Editorial policy · Methodology & sources

Your Coast FIRE scenario

Include investments intended for retirement; avoid counting the same asset twice.

Use today's purchasing power; inflation is applied automatically.

For example, a cautious pension or Social Security estimate.

Editable planning assumption — not a guaranteed safe rate.

Optional simplification. Use 0 for a tax-sheltered scenario.

Your Coast FIRE number today
$366,668
The planned contributions do not reach Coast by retirement
Retirement target
$1,853,944
Projected at retirement
$1,409,549
Modeled Coast age
Not reached
Required starting monthly
$1,492

Your planned balance funds 76% of the modeled target. Start around $1,492/month to reach it under these assumptions.

$927K$1.9MAge 36: $119,128 planned balance — $391,224 Coast thresholdAge 36: $119,128 planned balance — $391,224 Coast thresholdAge 37: $139,786 planned balance — $417,425 Coast thresholdAge 37: $139,786 planned balance — $417,425 Coast thresholdAge 38: $162,081 planned balance — $445,381 Coast thresholdAge 38: $162,081 planned balance — $445,381 Coast thresholdAge 39: $186,128 planned balance — $475,209 Coast thresholdAge 39: $186,128 planned balance — $475,209 Coast thresholdAge 40: $212,049 planned balance — $507,034 Coast thresholdAge 40: $212,049 planned balance — $507,034 Coast thresholdAge 41: $239,975 planned balance — $540,991 Coast thresholdAge 41: $239,975 planned balance — $540,991 Coast thresholdAge 42: $270,046 planned balance — $577,223 Coast thresholdAge 42: $270,046 planned balance — $577,223 Coast thresholdAge 43: $302,411 planned balance — $615,880 Coast thresholdAge 43: $302,411 planned balance — $615,880 Coast thresholdAge 44: $337,229 planned balance — $657,127 Coast thresholdAge 44: $337,229 planned balance — $657,127 Coast thresholdAge 45: $374,670 planned balance — $701,136 Coast thresholdAge 45: $374,670 planned balance — $701,136 Coast thresholdAge 46: $414,915 planned balance — $748,092 Coast thresholdAge 46: $414,915 planned balance — $748,092 Coast thresholdAge 47: $458,159 planned balance — $798,193 Coast thresholdAge 47: $458,159 planned balance — $798,193 Coast thresholdAge 48: $504,608 planned balance — $851,650 Coast thresholdAge 48: $504,608 planned balance — $851,650 Coast thresholdAge 49: $554,484 planned balance — $908,686 Coast thresholdAge 49: $554,484 planned balance — $908,686 Coast thresholdAge 50: $608,021 planned balance — $969,543 Coast thresholdAge 50: $608,021 planned balance — $969,543 Coast thresholdAge 51: $665,472 planned balance — $1,034,475 Coast thresholdAge 51: $665,472 planned balance — $1,034,475 Coast thresholdAge 52: $727,105 planned balance — $1,103,756 Coast thresholdAge 52: $727,105 planned balance — $1,103,756 Coast thresholdAge 53: $793,207 planned balance — $1,177,676 Coast thresholdAge 53: $793,207 planned balance — $1,177,676 Coast thresholdAge 54: $864,084 planned balance — $1,256,547 Coast thresholdAge 54: $864,084 planned balance — $1,256,547 Coast thresholdAge 55: $940,063 planned balance — $1,340,701 Coast thresholdAge 55: $940,063 planned balance — $1,340,701 Coast thresholdAge 56: $1,021,493 planned balance — $1,430,490 Coast thresholdAge 56: $1,021,493 planned balance — $1,430,490 Coast thresholdAge 57: $1,108,745 planned balance — $1,526,292 Coast thresholdAge 57: $1,108,745 planned balance — $1,526,292 Coast thresholdAge 58: $1,202,218 planned balance — $1,628,511 Coast thresholdAge 58: $1,202,218 planned balance — $1,628,511 Coast thresholdAge 59: $1,302,335 planned balance — $1,737,575 Coast thresholdAge 59: $1,302,335 planned balance — $1,737,575 Coast thresholdAge 60: $1,409,549 planned balance — $1,853,944 Coast thresholdAge 60: $1,409,549 planned balance — $1,853,944 Coast threshold364146515660
Funded toward thresholdGap to CoastAbove Coast threshold
Current investments: $100,000Future contributions: $384,364Modeled growth: $925,186
Current investmentsFuture contributionsModeled growth
Stress-test before trusting the headline

At a 5.0% return and 3.5% withdrawal rate, the Coast number becomes $689,320. This is a sensitivity check, not a worst case.

AgeCoast thresholdNo more contributionsPlanned balanceStatus
36$391,224$106,697$119,128Below Coast
37$417,425$113,843$139,786Below Coast
38$445,381$121,467$162,081Below Coast
39$475,209$129,602$186,128Below Coast
40$507,034$138,282$212,049Below Coast
41$540,991$147,543$239,975Below Coast
42$577,223$157,424$270,046Below Coast
43$615,880$167,967$302,411Below Coast
44$657,127$179,216$337,229Below Coast
45$701,136$191,218$374,670Below Coast
46$748,092$204,025$414,915Below Coast
47$798,193$217,689$458,159Below Coast
48$851,650$232,268$504,608Below Coast
49$908,686$247,823$554,484Below Coast
50$969,543$264,420$608,021Below Coast
51$1,034,475$282,129$665,472Below Coast
52$1,103,756$301,023$727,105Below Coast
53$1,177,676$321,184$793,207Below Coast
54$1,256,547$342,694$864,084Below Coast
55$1,340,701$365,645$940,063Below Coast
56$1,430,490$390,133$1,021,493Below Coast
57$1,526,292$416,260$1,108,745Below Coast
58$1,628,511$444,138$1,202,218Below Coast
59$1,737,575$473,883$1,302,335Below Coast
60$1,853,944$505,620$1,409,549Below Coast

What Coast FIRE means

You reach Coast FIRE when the money already invested could grow to your chosen retirement target without further contributions, assuming the return, fees, tax drag, inflation and withdrawal rate you entered. You would still need income for today's living costs; the idea is that retirement saving could become optional under that mathematical scenario.

The green Coast number is the balance needed now. The chart then moves the threshold forward each year and compares it with your planned balance. If your balance crosses the threshold, the calculator identifies the first modeled month and age when the plan could begin to coast.

How the Coast FIRE number is calculated

First, the calculator subtracts reliable retirement income entered in today's money from desired annual retirement spending. It inflates the remaining portfolio-funded spending to retirement, then divides it by the selected withdrawal rate to estimate a retirement portfolio target.

That future target is discounted back month by month using the assumed return after annual fees and the optional tax-drag estimate. The result is today's Coast FIRE number. Contributions are added at the beginning of each month, and an annual contribution increase applies after each completed year.

Why the withdrawal rate is editable

The often-cited 4% rule came from historical US market research, not a universal guarantee. Retirement length, portfolio mix, sequence of returns, investment costs, tax, country and future inflation can all change what is sustainable. Early retirees may need to plan for a horizon much longer than 30 years.

Use 4% only as a starting scenario. Try a lower rate such as 3% or 3.5% and a lower return to see how sensitive the Coast number is. A higher Coast number in the conservative case is useful information, not a failed plan.

What the model includes — and what it cannot predict

The model includes current investments, monthly contributions, annual contribution increases, inflation, fees, an optional user-estimated tax drag and reliable retirement income. Currency changes the display only; the calculation is the same in every country.

It does not simulate volatile yearly returns, sequence-of-returns risk, changing tax laws, pension eligibility, account limits or one-off expenses. Treat the output as a transparent planning scenario, not a forecast or a recommendation to stop saving.

Frequently asked questions

What is my Coast FIRE number?

It is the invested balance needed today to grow to your selected retirement portfolio target without further contributions, under the exact return, fee, tax-drag, inflation and withdrawal assumptions shown.

Does Coast FIRE mean I can retire now?

No. Coast FIRE normally means retirement contributions may no longer be required in the modeled scenario. You still need to fund all living costs until retirement and the investment outcome is uncertain.

Should I use a 4% withdrawal rate?

Four percent is a commonly cited historical starting point, not a universal safe rate. Test lower rates and consider retirement length, costs, tax, portfolio mix and your country before making decisions.

How should I enter a pension or Social Security?

Enter the reliable annual amount you expect in today's money. The calculator subtracts it from desired retirement spending before calculating the portfolio target. Use a cautious estimate and do not include income that is already counted elsewhere.

What is tax drag?

Tax drag is an optional simplified annual reduction to investment return. It can represent recurring tax leakage in a taxable account, but it is not a country tax calculation. Leave it at zero for a tax-sheltered scenario or when you prefer to model tax separately.

Why does my Coast FIRE number change so much with return?

The target compounds over many years. A small return change affects every future month, so the amount required today can move substantially. Comparing several return scenarios is more informative than relying on one result.

Research context: William Bengen's 4% rule research and FINRA on managing retirement income. Formula and source notes are documented in our methodology.