What Is Coast FIRE?
Coast FIRE represents a powerful milestone on the path to financial independence: the point where you've accumulated enough savings that compound growth alone will build your retirement fund — without saving another dollar. Once you hit your Coast FIRE number, your only financial requirement is earning enough to cover today's living expenses.
Think of it this way: traditional retirement planning says "save until 65." Traditional FIRE says "save until you can quit entirely." Coast FIRE says "save intensely until you reach the tipping point, then coast." It's a middle path that acknowledges many people don't want to defer all life satisfaction until they have millions saved.
The Coast FIRE Formula
Calculating your Coast FIRE number requires working backward from your retirement target:
Coast FIRE Number = Target Retirement Portfolio ÷ (1 + real return)^years
Where "real return" is your expected investment return minus inflation
Example Calculation:
- Target at age 65: $1,500,000 (for $60,000/year expenses)
- Current age: 32 (33 years until retirement)
- Expected real return: 5% annually
- Coast FIRE number: $1,500,000 ÷ (1.05)^33 = $299,189
This means a 32-year-old with ~$300,000 saved could theoretically stop all retirement contributions and still reach $1.5M by 65, assuming 5% real returns. Of course, they'd still need income for current expenses — they just wouldn't need to save any of it.
Understanding the Math: Compound Growth
Coast FIRE's power comes from compound interest — what Albert Einstein allegedly called the "eighth wonder of the world." Money invested for long periods grows exponentially, not linearly.
Consider how $100,000 grows at 7% nominal returns (before inflation):
| Years | Portfolio Value | Growth |
|---|---|---|
| 10 | $196,715 | ~2x |
| 20 | $386,968 | ~4x |
| 30 | $761,226 | ~7.6x |
| 35 | $1,067,658 | ~10.7x |
This exponential growth is why early savings are so powerful — and why Coast FIRE works. A dollar saved at 25 does far more work than a dollar saved at 55.
Coast FIRE Ages: When to Target Which Number
Your Coast FIRE number depends heavily on when you want to "coast" versus when you plan to fully retire. Here's how the numbers shift for someone targeting $1,500,000 at age 65:
| Coast at Age | Years Until 65 | Coast FIRE Number (5% real) |
|---|---|---|
| 25 | 40 | $213,109 |
| 30 | 35 | $271,978 |
| 35 | 30 | $347,125 |
| 40 | 25 | $442,924 |
| 45 | 20 | $565,329 |
Who Is Coast FIRE For?
Coast FIRE isn't for everyone, but it's particularly appealing in these situations:
Career Changers
If you're burned out in a high-paying but stressful career, Coast FIRE lets you switch to lower-paying work you actually enjoy. A lawyer might become a teacher, an investment banker might open a coffee shop, or a software engineer might become a part-time consultant. The math works because you only need to cover current expenses, not save for retirement.
Entrepreneurs
Starting a business is risky. Having your retirement already secured means you can take entrepreneurial risks without jeopardizing your financial future. Even if the business fails, your coast portfolio keeps growing toward traditional retirement.
Parents
Coast FIRE allows one parent to step back from full-time work for childcare without the guilt of "falling behind" on retirement savings. The savings done before kids arrives continues growing.
Creatives and Passion-Workers
Writers, artists, musicians, and other creative professionals often earn irregular, modest incomes. Coast FIRE lets them pursue their craft full-time, knowing retirement is handled regardless of artistic success.
Coast FIRE vs Other FIRE Types
Understanding how Coast FIRE compares to other approaches helps you choose the right strategy:
| Strategy | Work Required | Portfolio Needed |
|---|---|---|
| Traditional FIRE | None (fully retired) | 25x annual expenses |
| Coast FIRE | Cover current expenses only | Varies by age (see above) |
| Barista FIRE | Part-time (50% of expenses) | 12.5x annual expenses |
| Lean FIRE | None (frugal retirement) | 25x minimal expenses |
Risks and Limitations of Coast FIRE
While Coast FIRE is appealing, it's important to understand the risks:
Market Dependence
Coast FIRE relies heavily on long-term market returns. If the next 30 years deliver 4% real returns instead of 6%, your coast portfolio may fall short. This is why conservative return assumptions (5% real) are important, and why some buffer in your coast number provides peace of mind.
Inflation Risk
Your target retirement expenses will grow with inflation. A $40,000/year lifestyle today might cost $70,000 in 25 years at 3% inflation. Always calculate using real (inflation-adjusted) returns to account for this.
Healthcare in the US
If you're in the US and leave a full-time job with health benefits, you'll need to budget $6,000-$15,000+ annually for health insurance until Medicare at 65. This significantly increases the income you need while "coasting."
Lifestyle Inflation
Your expenses at 35 might not match your expenses at 55. If your lifestyle inflates significantly, your coast number becomes insufficient. Regular recalculation helps catch this early.
How to Accelerate to Coast FIRE
If Coast FIRE appeals to you but you're not there yet, focus on these strategies:
- Maximize early savings. Every dollar saved in your 20s and 30s has decades to compound. Front-load your savings career.
- Reduce current expenses. Lower expenses mean you need less income while coasting AND a smaller retirement target.
- Increase income temporarily. Consider grinding in a high-paying career for 5-10 years, then coasting. The concentrated effort pays off through decades of freedom.
- Take advantage of employer matches. Free money in 401(k) matches accelerates your coast number significantly.
- Avoid lifestyle creep. As income rises, keep expenses stable and funnel the difference into investments.
Psychological Benefits of Coast FIRE
Beyond the financial math, Coast FIRE offers significant psychological benefits:
- Reduced financial anxiety. Knowing retirement is "handled" regardless of future income reduces money stress.
- Career freedom. You can optimize for job satisfaction, learning, or impact rather than compensation.
- Better work-life balance. Part-time work or reduced hours become viable options.
- Risk tolerance for opportunities. Starting businesses, taking sabbaticals, or pursuing education becomes less scary.
Calculate Your Coast FIRE Number
Our calculator computes your Coast FIRE number automatically based on your inputs. It factors in:
- Your current age and target retirement age
- Your annual expenses (to determine retirement target)
- Expected real investment returns
- Your current savings across all accounts
The calculator shows not just your coast number, but how many years until you reach it at your current savings rate — and what changes could accelerate your timeline.
Disclaimer: Coast FIRE calculations assume consistent market returns, which don't reflect real-world volatility. These projections are for educational planning purposes. Actual results will vary. Consult a financial advisor for personalized guidance. Read our full disclaimer.