Coast FIRE Calculator

Coast FIRE is the financial independence milestone where your existing investments — left untouched — will grow to your retirement goal by themselves. You no longer need to save; you only need to earn enough to cover current expenses.

Coast FIRE Formula: Coast FIRE Number = Target / (1 + r)^n

Variable definitions:

• Target = total amount needed at retirement (often 25× annual expenses, based on the 4% rule)
• r = expected annual real investment return (historically 7% for a diversified index fund portfolio)
• n = years from now until target retirement age

The 4% Safe Withdrawal Rule: If you withdraw 4% of your portfolio per year in retirement, historical data shows the portfolio survives 30+ years in almost all market conditions. Retirement Target = Annual Expenses × 25

Worked example:

• Current age: 32 | Target retirement: 65 → n = 33 years
• Annual retirement expenses: $50,000 → Target = $1,250,000
• Expected return: 7% annually
• Coast FIRE = $1,250,000 / (1.07)^33 = $131,500

Once you have $131,500 invested, you can stop contributing entirely and your portfolio will reach $1.25M by age 65.

Why this matters: Reaching Coast FIRE unlocks massive lifestyle flexibility. You can switch to part-time work, take a lower-paying job you love, or move to a lower cost-of-living area — because your retirement is already “funded” through compound growth.

Inflation note: Use a real (inflation-adjusted) return of ~4–5% if you want results in today’s dollars, or 7% nominal with a higher target that accounts for future inflation.