COAST FIRE Calculator

Spluxly’s free online Coast FIRE Calculator is a comprehensive retirement planning tool designed for financial independence seekers, early retirement planners, and anyone following the FIRE (Financial Independence Retire Early) movement. Coast FIRE is a specific milestone within the FIRE strategy — the point at which you have saved and invested enough money that, even without making any further contributions, your existing portfolio will grow through compound interest alone to reach your full financial independence number by your target retirement age. To use the calculator, enter your current age, target retirement age, current investment portfolio value, expected annual expenses during retirement, expected investment return rate, inflation rate, and safe withdrawal rate. The calculator instantly returns your Coast FIRE number (the amount you need invested today to stop contributing), the number of years until you reach that Coast number, and your projected retirement portfolio value at your target retirement age. Results are accompanied by a dynamic portfolio growth trajectory chart showing how your investments grow from today through to retirement. Completely free, no registration required, and accessible on any device.

How to Use the Coast FIRE Calculator Online

Calculating your Coast FIRE number takes just a few seconds. Follow these simple steps:

• Enter Your Current Age – Input your age today (e.g., 30) as the starting point for the calculation
• Enter Target Retirement Age – Input the age at which you plan to retire or reach full financial independence (e.g., 60)
• Enter Current Investments – Input the current total value of your investment portfolio in dollars (e.g., $50,000)
• Enter Annual Retirement Expenses – Input the amount you expect to spend per year during retirement in today’s dollars (e.g., $40,000)
• Set Expected Return Rate – Enter your anticipated average annual investment return rate as a percentage (e.g., 7%)
• Set Inflation Rate – Enter the assumed average annual inflation rate (e.g., 3%) to adjust your retirement target for purchasing power
• Set Safe Withdrawal Rate – Enter the percentage of your portfolio you plan to withdraw annually in retirement (e.g., 4%, the widely referenced safe withdrawal rate)
• Click Calculate COAST FIRE – Instantly receive your Coast FIRE number, years to coast, projected retirement portfolio value, and portfolio growth chart
• Review Additional Insights – Read the personalised feedback indicating whether you have already reached your Coast number or how far you still need to go

How Coast FIRE Is Calculated

The Coast FIRE Calculator uses compound interest and inflation-adjusted retirement planning formulas to determine your Coast number and growth trajectory.

Step 1 – Calculate the Inflation-Adjusted Retirement Target (FIRE Number): The full FIRE number is the total portfolio value needed at retirement to sustain your desired annual expenses indefinitely using the safe withdrawal rate.

FIRE Number = Annual Retirement Expenses ÷ Safe Withdrawal Rate

Example: $40,000 annual expenses ÷ 4% withdrawal rate = $1,000,000 FIRE Number

This figure is then adjusted for inflation over the years between today and retirement to reflect the future purchasing power needed.

Step 2 – Calculate the Coast FIRE Number: The Coast FIRE number is the amount you need invested today so that, growing at the expected return rate with no further contributions, it reaches your inflation-adjusted FIRE number by retirement age.

Coast FIRE Number = Future FIRE Number ÷ (1 + Return Rate)^(Years to Retirement)

Example: $1,000,000 future target ÷ (1.07)^30 = approximately $131,367 Coast FIRE Number

This means if you have $131,367 invested today at age 30 with a 7% return, you can stop contributing entirely and your portfolio will grow to $1,000,000 by age 60.

Step 3 – Calculate Years to Coast: If your current portfolio is below the Coast FIRE number, the calculator determines how many additional years of contributions at your current savings rate are needed to reach that threshold.

Step 4 – Generate Portfolio Growth Trajectory: A year-by-year projection of portfolio growth from today through retirement age is plotted on the dynamic chart, with the Coast FIRE number marked as a reference line.

Why Use Spluxly’s Coast FIRE Calculator?

• Coast FIRE Number Calculation – Precisely determines the exact amount you need invested today to stop making retirement contributions entirely, letting compound growth alone carry your portfolio to your full FIRE number by retirement age
• Inflation-Adjusted Projections – Incorporates your specified inflation rate to adjust the retirement target for future purchasing power, ensuring your Coast number reflects real-world costs rather than today’s dollar values alone
• Safe Withdrawal Rate Customisation – Allows you to set your own safe withdrawal rate rather than locking you into a fixed assumption, giving flexibility for conservative (3%), standard (4%), or aggressive (5%) retirement spending strategies
• Dynamic Portfolio Growth Chart – An interactive visual chart plots your portfolio’s projected growth trajectory from today through to retirement age with the Coast FIRE number displayed as a clear reference line, making the path to financial independence easy to visualise
• Years to Coast Result – In addition to the Coast number, the calculator tells you exactly how many more years of contributions are needed before you can stop saving and coast to retirement
• Personalised Actionable Insights – The results section includes tailored feedback indicating your current readiness status — whether you have already coasted, are close, or still have a defined gap to close
• 100% Free & Instant – No registration, no fees, and no app download required — enter your financial details and receive your full Coast FIRE number, years to coast, retirement portfolio projection, and growth chart in seconds on any device