Coast FIRE is the point where your invested assets will grow to your full retirement target through compound returns alone, even if you never save another dollar. Knowing your Coast FIRE number lets you decide when to downshift from aggressive saving to simply covering living expenses, unlocking flexibility to pursue passion projects, reduce work hours, or change careers years before full retirement.
Your Financial Details
Use current expenses as a proxy if unsure
Keep Contributing vs Coast
Keep Contributing
Coast (Stop at Coast FIRE Age)
Coast FIRE Number by Age
Year-by-Year Projection
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How to Use the Coast FIRE Calculator
Coast FIRE is one of the most liberating milestones in the financial independence journey. Unlike full FIRE, which requires a portfolio large enough to live off immediately, Coast FIRE means your investments have reached a tipping point where compound growth will do the heavy lifting from here on out. This calculator helps you find that exact tipping point and plan around it.
Step 1: Enter Your Age and Retirement Target
Start with your current age and the age you want to retire. The gap between these two numbers is critical because it determines how long compound growth has to work. A 30-year-old targeting age 65 has 35 years of compounding, which means a much lower Coast FIRE number than someone with only 15 years to go. This is why starting early has such an outsized impact.
Step 2: Enter Your Assets and Expenses
Your current invested assets include 401(k), IRA, brokerage, and other investment accounts. For annual retirement expenses, use your current spending as a starting point. The calculator uses expenses and the safe withdrawal rate to compute your FIRE number (expenses divided by the SWR), which is the ultimate portfolio target that Coast FIRE works backward from.
Step 3: Set Return, Inflation, and Withdrawal Rates
The calculator separates nominal return and inflation to compute a real (inflation-adjusted) return rate. A 7% nominal return with 3% inflation gives roughly a 3.9% real return. The Coast FIRE number is your FIRE target discounted by this real return over the years remaining until retirement. The safe withdrawal rate determines how large your FIRE target is in the first place.
Step 4: Understand Your Results
The calculator shows whether you have already reached Coast FIRE and, if not, projects the age at which you will reach it given your current monthly contributions. The chart visualizes how the Coast FIRE number declines as you age (fewer years of compounding remaining means you need more saved) while your portfolio grows. Where the lines cross is your Coast FIRE age. The comparison section shows the difference between continuing to contribute versus coasting after reaching the milestone.
Step 5: Experiment with Scenarios
Try adjusting your monthly contributions, retirement age, or expected return to see how each variable shifts your Coast FIRE age. Reducing retirement expenses has a double effect: it lowers your FIRE number and, consequently, your Coast FIRE number. Even small changes in the return rate compound significantly over decades. All calculations run privately in your browser with no data stored or transmitted.
FAQ
Is this Coast FIRE calculator free?
Yes, this Coast FIRE calculator is completely free with no signup, no account, and no limits. All calculations run entirely in your browser using client-side JavaScript. Your financial data is never sent to any server or stored anywhere.
Is my financial data safe and private?
Absolutely. Everything runs locally in your web browser. Your age, savings, expenses, and investment figures are never transmitted to any server. You can disconnect from the internet after loading the page and the calculator will continue to work.
What is Coast FIRE?
Coast FIRE is a financial milestone where you have enough invested that compound growth alone will carry your portfolio to your full retirement target by your desired retirement age, even if you never contribute another dollar. Once you reach Coast FIRE, you only need to earn enough to cover your current living expenses.
How is the Coast FIRE number calculated?
The Coast FIRE number equals your FIRE target divided by (1 + real return rate) raised to the power of years until retirement. It is the present value of your FIRE number, discounted by expected real investment returns. For example, if your FIRE number is $1.25M, your real return is 4%, and you have 25 years to retirement, your Coast FIRE number is about $375K.
What is the difference between Coast FIRE and regular FIRE?
Regular FIRE means your portfolio is large enough right now to fund your retirement through withdrawals. Coast FIRE means your portfolio is large enough that future compound growth alone will get it to the FIRE number by retirement age. Coast FIRE is a milestone you reach years before full FIRE, allowing you to reduce or stop retirement contributions.
What return rate should I use for Coast FIRE?
A commonly used real (inflation-adjusted) return rate for a diversified stock index portfolio is 4-5%. This calculator lets you enter both nominal return and inflation separately, computing the real return automatically. Using real returns ensures your FIRE number reflects actual purchasing power at retirement.
Can I really stop contributing after reaching Coast FIRE?
Mathematically yes, but there are caveats. Markets do not deliver smooth returns every year, so having a cushion above your Coast FIRE number provides safety margin. Many Coast FIRE practitioners continue saving at a reduced rate rather than stopping completely, or they shift to lower-paying but more fulfilling work that covers living expenses.
What safe withdrawal rate should I use?
The classic 4% safe withdrawal rate comes from the Trinity Study and has historically supported a 30-year retirement with over 95% success. If you plan to retire very early with a 40+ year retirement, consider using 3.5% or 3% for extra safety. A lower withdrawal rate increases your FIRE target and Coast FIRE number.