Coast FIRE Calculator
Find your Coast FIRE number — the invested amount needed today so compound growth alone reaches your retirement goal without further contributions.
About this calculator
Coast FIRE is the point at which your existing invested assets are large enough that compound growth alone -- with zero further contributions -- will reach your retirement number by your target retirement age. This calculator works backward from that idea: Coast FIRE Number divides Target Retirement Number by (1 + Expected Annual Return) raised to the power of Years of Growth Remaining (Retirement Age minus Current Age), which is the amount you'd need invested today to compound, untouched, into your target. Already Coast FIRE? compares that number to your Current Investments and reports Yes if you've already crossed the threshold.
Projected Value at Retirement separately shows what your Current Investments alone would grow to by Retirement Age at the entered return, assuming no more money goes in -- a useful sanity check even if you haven't hit Coast FIRE yet, since it shows how far short (or how far over) your current trajectory lands. Reaching Coast FIRE doesn't mean you should stop earning; it means you could stop actively saving for retirement and instead cover current living expenses from income alone (including lower-paying, more flexible work -- the idea behind the related 'Barista FIRE' concept), while your existing portfolio does the rest of the compounding on its own. The 'expected annual return' input should reflect a REAL (inflation-adjusted) return if Target Retirement Number is expressed in today's dollars, since mixing a nominal return assumption with a real-dollar target overstates how close you are.
Financial Disclaimer
This calculator is for educational purposes only and does not constitute financial advice. Results are estimates based on the inputs provided. Consult a qualified financial advisor before making investment or financial planning decisions.
Inputs
Results
Coast FIRE Number
$140,494.41
≈ 9 used cars
How to Use This Calculator
- Enter your current age and target retirement age.
- Input your current invested assets (401(k), IRA, brokerage accounts).
- Enter your target retirement number — typically 25x your expected annual expenses.
- Set your expected annual real return on investments.
- Review your Coast FIRE number — if your current investments already equal this amount, they will grow to your retirement target without any more contributions.
How the result changes with Retirement Age
| Retirement Age | Coast FIRE Number |
|---|---|
| 33 | $1,224,446.82 |
| 49 | $414,762.50 |
| 90 | $25,885.98 |
What each input means
- Current Age
- Your current age in years.
- Retirement Age
- Traditional retirement age when you want full financial independence.
- Current Investments
- Current value of invested assets (retirement accounts, brokerage, etc.).
- Target Retirement Number
- Total portfolio value you need at retirement (e.g. 25x annual expenses).
- Expected Annual Return
- Expected average annual real return on investments.
What each result means
- Already Coast FIRE?
- Yes if current investments already meet or exceed the Coast FIRE Number.
How this is calculated
Worked example, using the default values
- Identify Input Parameters5 parametersCurrent Age = 30, Retirement Age = 65, Current Investments = 150000, Target Retirement Number = 1500000, Expected Annual Return = 7 = 5 input(s) provided
- Calculate Coast FIRE NumberCoast FIRE Number140494.41 = $140,494.41
- Calculate Already Coast FIRE?Already Coast FIRE?Yes = Yes
- Calculate Years of Growth RemainingYears of Growth Remaining35 = 35
Engine last updated . Checked against 1 independently-derived test — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why does raising Retirement Age lower my Coast FIRE Number?
More years until retirement means more time for compound growth to work, so a smaller starting amount needs to grow to the same Target Retirement Number. The calculator divides your target by (1 + return) raised to the power of years remaining -- a bigger exponent (more years) produces a bigger divisor, and a bigger divisor produces a smaller required amount today.
Does my Current Investments amount change my Coast FIRE Number?
No. Coast FIRE Number is calculated purely from your Target Retirement Number, Expected Annual Return, and years remaining until Retirement Age -- it's the amount you'd need, not the amount you have. Current Investments is compared against that calculated number separately to answer 'have I reached it yet' (Already Coast FIRE?) and to project where your current balance alone will land (Projected Value at Retirement).
Why does raising Current Age (with Retirement Age fixed) increase my Coast FIRE Number?
Raising Current Age while holding Retirement Age steady shrinks Years of Growth Remaining -- there's less time left for compounding. With less time to grow, you need a larger amount invested today to still reach the same Target Retirement Number, so Coast FIRE Number goes up as the runway gets shorter.
Should I use a nominal or inflation-adjusted return?
Use an inflation-adjusted (real) return if your Target Retirement Number is expressed in today's purchasing power, which is the more common way to set a retirement goal. A commonly cited long-run real historical stock market return is in the 6-7% range, well below typical nominal return figures, which include inflation. Mixing a nominal return with a real-dollar target will make you look closer to Coast FIRE than you actually are.
What does this calculator not account for?
It assumes a single constant annual return with no volatility, sequence-of-returns risk, taxes on withdrawals, or contributions/withdrawals between now and retirement -- 'coasting' means literally zero further deposits in this model. It also doesn't verify that Target Retirement Number itself is sized correctly for your spending needs; pair it with a separate withdrawal-rate or retirement-number calculation.
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