coastfire calculator

What Is CoastFIRE?

CoastFIRE means you have enough invested that, with no additional contributions, compound growth can carry your portfolio to your full retirement target by your chosen retirement age. In plain English: once you hit your CoastFI number, you can choose to reduce savings, switch to part-time work, or pursue lower-stress work while your investments keep compounding.

This approach sits between traditional retirement saving and full early retirement. You are not fully financially independent today, but you are “coasting” toward it with time doing most of the work.

How This Calculator Works

The calculator uses your spending goal, withdrawal rate, timeline, and expected real return (return after inflation) to estimate:

• Your FI target at retirement
• Your CoastFI number today (if you stopped contributing now)
• The required portfolio at your Coast age
• Your projected balance at Coast age based on current savings and monthly contributions
• The monthly contribution needed to hit CoastFI by your selected Coast age

Input Guide

1) Ages (Current, Coast, Retirement)

These define your timeline. A longer runway to retirement generally lowers the amount you need today because compounding has more time to work.

2) Current Portfolio and Monthly Contributions

Your current invested assets include taxable brokerage accounts, retirement accounts, and other long-term investment balances intended for retirement. Monthly contribution reflects what you can maintain until Coast age.

3) Annual Retirement Spending and Withdrawal Rate

Your FI target is estimated as:

FI Target = Annual Spending ÷ Withdrawal Rate

Example: $50,000 spending with a 4% withdrawal rate implies about $1,250,000 invested.

4) Return and Inflation Assumptions

The model converts nominal return and inflation into a real return:

Real Return ≈ ((1 + nominal return) ÷ (1 + inflation)) − 1

Real return keeps all values in “today’s dollars,” which helps you reason more clearly about future purchasing power.

Ways to Reach CoastFIRE Faster

• Increase savings rate early: front-loaded investing has the biggest compounding impact.
• Lower retirement spending target: even modest reductions can significantly shrink FI needs.
• Delay retirement age slightly: a few extra years can materially reduce pressure.
• Improve income: salary growth, freelancing, or side projects can accelerate progress.
• Reduce investment fees: lower drag means more compounding retained.

Common CoastFIRE Mistakes

• Using overly optimistic return assumptions
• Ignoring inflation and using nominal numbers inconsistently
• Forgetting taxes in retirement account withdrawals
• Underestimating healthcare and housing costs later in life
• Assuming spending is static across all retirement years

Quick Example Scenario

Suppose you are 30, want to coast at 40, retire at 60, have $120,000 invested, contribute $1,500/month until age 40, and want $50,000/year in retirement with a 4% withdrawal rate. With a 7% nominal return and 2.5% inflation, your real return is roughly 4.39%.

The calculator estimates whether your projected balance by age 40 is enough to grow on its own to your FI target by age 60. If not, it shows the monthly amount needed to bridge the gap.

Final Thoughts

CoastFIRE is less about escaping work immediately and more about gaining flexibility. Hitting your Coast number can buy you options: a career pivot, a sabbatical, family time, or lower-stress work without giving up long-term financial security.

Educational content only. Consider speaking with a fiduciary financial advisor for personalized guidance.