Coastfire Calculator Reddit

Calculate your CoastFIRE number and explore your path to early retirement.

CoastFIRE Inputs

Your CoastFIRE Numbers

This calculator estimates the lump sum you need to reach your desired retirement spending. By contributing only until your current savings can grow to that target amount *on its own*, you achieve CoastFIRE.

Data Table

Metric	Value	Notes
Current Age	—	Years
Current Savings	—	Currency
Annual Spending Target	—	Currency/Year
Desired Retirement Age	—	Years
Years to Coast	—	Years
Years in Retirement	—	Years
Real Rate of Return	—	%/Year (Post-Inflation)
Safe Withdrawal Rate	—	%/Year
CoastFIRE Portfolio Target	—	Currency
Projected Portfolio at Retirement	—	Currency

What is CoastFIRE?

CoastFIRE (Financial Independence, Retire Early) is a popular early retirement strategy often discussed on platforms like Reddit. It represents a stage in your financial journey where you've saved enough that your existing investments are projected to grow, *without any further contributions*, to cover your desired retirement expenses by your planned retirement age. Essentially, you've reached a "coast" phase where you can stop actively saving for retirement and let compound interest do the heavy lifting.

This strategy appeals to many because it offers flexibility. You can continue working your current job, switch to a lower-paying passion project, or take a sabbatical, all while knowing your future financial security is largely guaranteed. It's a less extreme version of traditional FIRE, allowing for a more balanced life during the accumulation phase.

Who Should Use a CoastFIRE Calculator?

• Individuals aiming for early retirement but seeking a less aggressive savings path.
• People who have already saved a substantial amount and want to see if they've reached their "coast" point.
• Those considering a career change to a lower-paying but more fulfilling role.
• Anyone interested in leveraging compound growth to achieve financial independence.

Common misunderstandings often revolve around the concept of "real" versus "nominal" returns, and the role of inflation. This calculator uses real returns (adjusted for inflation) to simplify planning, meaning the target spending is in today's dollars and the growth rate accounts for price increases.

CoastFIRE Calculator Formula and Explanation

The core of the CoastFIRE calculation involves determining how much your current savings need to grow to meet your retirement spending goal, and then calculating the "CoastFIRE Number" – the portfolio value at which this growth will happen automatically.

1. Calculate the Target Retirement Portfolio Value (Lean FIRE Number)

This is the total amount you need invested at retirement to sustain your desired annual spending using a safe withdrawal rate (SWR).

Formula: Target Portfolio = Annual Spending Target / (Safe Withdrawal Rate / 100)

Explanation: If you need $40,000 per year and use a 4% SWR, you need $40,000 / 0.04 = $1,000,000.

2. Calculate the CoastFIRE Number

This is the amount you need to have saved *today* (or at your "coast" point) such that it will grow to the Target Retirement Portfolio Value by your desired retirement age, assuming only investment growth (no further contributions).

Formula: CoastFIRE Number = Target Portfolio / (1 + (Real Rate of Return / 100)) ^ Years to Retirement

Explanation: If your Target Portfolio is $1,000,000, you want to retire in 20 years, and your real return is 5%, the CoastFIRE Number is $1,000,000 / (1 + 0.05)^20 ≈ $376,890.

3. Calculate Years to Coast

This is the duration from your current age until your current savings reach the calculated CoastFIRE Number, assuming you continue contributing until that point.

Formula: This is solved iteratively or through financial functions, approximating the number of years (Y) such that FV = PV * (1 + r)^Y, where FV is the CoastFIRE Number, PV is Current Savings, and r is the Real Rate of Return.

Simplified Calculation Approach: The calculator estimates this by seeing how long it takes for the current savings to grow to the CoastFIRE number using compound interest.

Variables Table

Variable	Meaning	Unit	Typical Range/Notes
Current Age	Your current age	Years	18+
Current Savings	Total retirement funds saved to date	Currency	≥ 0
Annual Spending Target	Projected annual expenses in retirement (in today's money)	Currency/Year	Realistic living expenses
Desired Retirement Age	Target age for retirement	Years	Often 50-60 for CoastFIRE
Real Rate of Return	Annual investment growth rate after inflation	% per Year	3-7% is common
Safe Withdrawal Rate (SWR)	Percentage of portfolio withdrawn annually in retirement	% per Year	3-4% is common
Years to Retirement	Time from current age to desired retirement age	Years	Calculated
Target Retirement Portfolio	Total funds needed at retirement	Currency	Calculated
CoastFIRE Number	Minimum portfolio value to reach "coast" status	Currency	Calculated
Years to Coast	Time until current savings reach CoastFIRE Number	Years	Calculated
Projected Portfolio at Retirement	Estimated portfolio value at retirement age if CoastFIRE is achieved	Currency	Calculated

Practical Examples

Example 1: The Ambitious Saver

Scenario: Sarah is 30 years old with $75,000 saved. She wants to retire at 50 (20 years) and estimates needing $50,000/year (in today's dollars). She assumes a 6% real return and a 4% SWR.

• Inputs: Current Age: 30, Current Savings: $75,000, Annual Spending Target: $50,000, Retirement Age: 50, Real Return Rate: 6%, Withdrawal Rate: 4%
• Calculations:
  • Target Retirement Portfolio = $50,000 / 0.04 = $1,250,000
  • CoastFIRE Number = $1,250,000 / (1 + 0.06)^20 ≈ $389,567
• Result: Sarah's CoastFIRE Number is approximately $389,567. Her current $75,000 is projected to grow to this amount in about 12 years (when she's 42). This means she can "coast" from age 42 to 50, letting her investments grow on their own. Her projected portfolio at 50 would be ~$1,250,000.

Example 2: The Early Achiever

Scenario: Ben is 35 years old with $200,000 saved. He wants to retire at 55 (20 years) and anticipates needing $60,000/year. He's more conservative, assuming a 5% real return and a 3.5% SWR.

• Inputs: Current Age: 35, Current Savings: $200,000, Annual Spending Target: $60,000, Retirement Age: 55, Real Return Rate: 5%, Withdrawal Rate: 3.5%
• Calculations:
  • Target Retirement Portfolio = $60,000 / 0.035 ≈ $1,714,286
  • CoastFIRE Number = $1,714,286 / (1 + 0.05)^20 ≈ $634,933
• Result: Ben's CoastFIRE Number is approximately $634,933. With $200,000 saved, he needs to save for roughly 8 years (until age 43) to reach his coast point. From age 43 to 55, he can coast. His projected portfolio at 55 would be ~$1,714,286.

How to Use This CoastFIRE Calculator

1. Input Current Age: Enter your current age in years.
2. Enter Current Savings: Input the total amount you have saved specifically for retirement (e.g., in 401(k)s, IRAs, brokerage accounts).
3. Define Annual Spending Target: Estimate your desired annual expenses in retirement, expressed in *today's* currency value. Be realistic about your lifestyle.
4. Set Desired Retirement Age: Choose the age at which you plan to retire.
5. Input Assumed Real Rate of Return: This is crucial. It's the average annual growth rate of your investments *after* accounting for inflation. A common range is 5-7%, but adjust based on your asset allocation and risk tolerance.
6. Specify Safe Withdrawal Rate (SWR): This percentage indicates how much of your retirement portfolio you plan to withdraw each year. The 4% rule is a popular benchmark, but some prefer lower rates (e.g., 3.5%) for greater safety, especially for longer retirements or CoastFIRE.
7. Click 'Calculate CoastFIRE': The calculator will compute your CoastFIRE Number, the projected portfolio value needed at retirement, and the estimated number of years until you reach your "coast" phase.
8. Interpret Results:
   • CoastFIRE Number: This is the target portfolio value you need to reach. Once your *current savings* are projected to grow to this amount by retirement age (without further contributions), you've achieved CoastFIRE.
   • Years to Coast: This tells you how long you need to continue saving and investing normally until your portfolio reaches the CoastFIRE Number.
   • Projected Portfolio at Retirement: This shows the estimated size of your retirement nest egg when you reach your desired retirement age, assuming you achieved CoastFIRE and stopped contributing.
9. Use the Chart and Table: The chart visualizes the growth trajectory, while the table provides a detailed breakdown of all inputs and outputs.
10. Reset: Click 'Reset' anytime to clear inputs and return to default values.

Selecting Correct Units: Ensure all currency inputs (Current Savings, Annual Spending Target) are in the same currency. The calculator works with nominal values representing today's purchasing power. The "Real Rate of Return" is key to properly adjusting for inflation.

Key Factors That Affect Your CoastFIRE Number

1. Time Horizon (Years to Retirement): The longer you have until retirement, the less your CoastFIRE Number will be. Compounding has more time to work its magic, requiring a smaller initial investment to reach the goal.
2. Assumed Real Rate of Return: A higher real rate of return significantly lowers your CoastFIRE Number. Even a 1% difference can drastically reduce the amount needed. However, chasing higher returns often involves taking on more risk.
3. Desired Annual Spending: This is the most direct lever. Lowering your expected retirement spending directly reduces the target portfolio size and thus your CoastFIRE Number.
4. Safe Withdrawal Rate (SWR): A higher SWR (e.g., 4.5% vs 3.5%) means you need a smaller portfolio to generate the same income, thus lowering the CoastFIRE Number. However, higher SWRs carry increased risk of running out of money.
5. Current Savings: The more you have saved *now*, the closer you are to your CoastFIRE Number. If your current savings already exceed the calculated CoastFIRE Number, you've already achieved it!
6. Inflation Assumptions: While this calculator uses *real* returns (implicitly handling inflation), unexpected inflation spikes could erode purchasing power faster than expected, making your target spending more expensive in the future.
7. Investment Fees and Taxes: High fees or taxes can significantly reduce your net returns, effectively lowering your "real rate of return." It's vital to consider these costs when estimating your growth rate.

FAQ

Q1: What's the difference between FIRE and CoastFIRE?

FIRE (Financial Independence, Retire Early) typically means accumulating a portfolio large enough to fully fund your retirement expenses from day one of retirement. CoastFIRE is a stepping stone; you save enough so that your existing assets will grow to your full retirement goal *on their own* by your target retirement age, allowing you to stop contributing sooner.

Q2: Can I use this calculator if my currency isn't USD?

Yes, as long as you are consistent. Input all currency values (current savings, desired spending) in your local currency. The calculator doesn't use specific currency symbols or conversion rates; it works with the numerical values you provide.

Q3: Is the "Real Rate of Return" the same as my investment's nominal return?

No. The "Real Rate of Return" is your investment's *nominal* return minus the rate of inflation. For example, if your investments yield 8% and inflation is 3%, your real return is 5%. Using real returns simplifies planning because your target spending is also in today's dollars.

Q4: How accurate is the "Years to Coast" calculation?

It's an estimate. It assumes consistent real returns, which don't happen in reality (markets fluctuate). It also assumes you stop contributing the moment you hit the CoastFIRE Number. It provides a good ballpark figure for planning.

Q5: What if my spending needs change before retirement?

If your desired annual spending increases, your Target Retirement Portfolio and CoastFIRE Number will increase, potentially pushing your CoastFIRE date further out. It's wise to periodically re-evaluate your goals and update the calculator.

Q6: What happens if the market performs poorly after I reach my CoastFIRE number?

If the market underperforms significantly *after* you've reached your CoastFIRE number but *before* your official retirement age, your portfolio might not grow as projected. This could delay your ability to coast or require you to work longer. It highlights the importance of using conservative return assumptions.

Q7: Should I include my emergency fund or home equity in "Current Savings"?

No. "Current Savings" for this calculator should only include assets specifically earmarked for retirement (e.g., in tax-advantaged accounts like 401(k)s, IRAs, or a taxable brokerage account invested for the long term). Emergency funds and home equity are typically excluded.

Q8: What's the difference between CoastFIRE and Barista FIRE?

CoastFIRE means your investments will grow to cover your retirement needs without further contributions. Barista FIRE involves working part-time (often in flexible, lower-stress jobs like a "barista") to cover ongoing living expenses, using investment returns primarily for healthcare or supplemental income, with a smaller portfolio needed compared to full FIRE.