What Is Coast FIRE?
Coast FIRE is a milestone on the path to financial independence where you have accumulated enough in investments that — even without contributing another dollar — compound growth will carry your portfolio to your full retirement goal. The name captures the feeling: once you reach this number, you stop paddling and simply coast.
The math is straightforward compound interest working in your favor. If you have 35 years until retirement and expect 7% annual growth, every dollar invested today becomes roughly $10.68 by retirement. That leverage means you need far less saved now than you will eventually spend — the market does the heavy lifting. Age matters enormously: a 25-year-old needs to accumulate far less than a 35-year-old targeting the same retirement number, because time does the work.
Once you reach Coast FIRE, your options expand dramatically. You can switch to a lower-paying but more fulfilling career, cut to part-time, take a sabbatical, or simply stop maximizing retirement contributions and enjoy more of your income today. Your future self is already taken care of. To understand how Coast FIRE fits within the broader FIRE movement, read: The FIRE Movement Explained: Financial Independence, Retire Early.
Frequently Asked Questions
What exactly is the Coast FIRE number?
Your Coast FIRE number is the lump sum you need invested today so that, with no additional contributions and your expected rate of return, your portfolio reaches your target retirement balance exactly when you retire. The formula is: Coast FIRE = Retirement Goal ÷ (1 + annual return)years to retirement.
Is a 7% annual return a realistic assumption?
Seven percent real (inflation-adjusted) return is a widely used conservative benchmark derived from long-run US equity data. The nominal S&P 500 average is closer to 10%; subtracting ~3% for inflation yields ~7%. Conservative planners use 5-6%. Always run your numbers at multiple assumptions to see the full range of outcomes.
What can I do once I reach Coast FIRE?
You no longer need to save for retirement — your portfolio handles it from here. Common next steps: switch to a more fulfilling lower-paying career, go part-time, start a side business with less financial pressure, or redirect savings toward other goals like travel, education, or real estate. The key is that your retirement future is already funded.
How is Coast FIRE different from regular FIRE?
Full FIRE means your investments can cover your entire cost of living right now — you can quit work immediately. Coast FIRE is an earlier milestone: retirement is on autopilot, but you still need income for today’s living expenses. Coast FIRE buys flexibility today; full FIRE buys complete work optionality. Lean FIRE and Fat FIRE refer to the size of the retirement target, not the timing.