Coast FIRE Calculator
Calculate your Coast FIRE number — the amount you need saved now so you can stop contributing and still retire on time through investment growth alone.
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.