Coast FIRE is a milestone within the broader FIRE movement. You have reached Coast FIRE when your current invested balance is large enough that, left untouched, it will grow to your full FIRE number by your target retirement age, with no additional contributions required. At that point, you can "coast" to retirement, covering only your current living expenses without saving aggressively.
How Coast FIRE Differs from Full FIRE
Full FIRE means you can stop working entirely right now. Your portfolio is large enough to fund all your expenses through investment withdrawals.
Coast FIRE means you can stop saving aggressively right now. You still need income to cover today's expenses, but you no longer need to direct extra money toward retirement. Any job that pays the bills is sufficient, which opens up a much wider range of options: part-time work, lower-stress careers, freelancing, or even a career change that previously felt financially impractical.
The Coast FIRE Formula
Coast FIRE Number = FIRE Number / (1 + r)^years
Where:
- FIRE Number = your full retirement target (annual expenses / SWR)
- r = expected annual investment return (as a decimal)
- years = years between today and your target retirement age
Example: You want $1,000,000 by age 65. You are currently 35. You expect a 7% average annual return.
Coast FIRE Number = $1,000,000 / (1 + 0.07)^30
Coast FIRE Number = $1,000,000 / 7.612
Coast FIRE Number = $131,367
If you have $131,367 invested today and leave it completely alone, it will grow to roughly $1,000,000 by age 65 at 7% annual returns. You have reached Coast FIRE.
What "Coasting" Looks Like in Practice
After hitting Coast FIRE, the financial calculus changes. You no longer need to maximize your savings rate. You just need to earn enough to cover your current lifestyle without drawing down your investments.
For someone in their 30s, this might mean leaving a high-paying but exhausting job in favor of something more enjoyable or meaningful, even at a lower salary. The retirement portfolio takes care of itself in the background.
This is different from Barista FIRE, a related concept where you work part-time specifically to access employer health benefits while drawing a small amount from your portfolio. Coast FIRE relies entirely on future growth, not withdrawals.
Why Coast FIRE Appeals to People in Their 30s and 40s
The math of compounding makes Coast FIRE achievable surprisingly early, especially for people who saved aggressively in their 20s. A 30-year-old with $150,000 already invested needs zero additional contributions to reach $1,000,000+ by 65 at historical market returns.
That realization changes the entire framing of financial decisions. Instead of grinding toward a distant FIRE number, you are managing a much smaller, more achievable target. Once crossed, every dollar you save beyond living expenses becomes optional rather than necessary.
The psychological shift is significant. Knowing your retirement is funded, even if decades away, removes a specific type of financial anxiety that affects a lot of people in the peak earning years of their career.
Calculate Your Coast FIRE Number
To find your personal coast number based on your age, target retirement age, FIRE target, and expected return, use the Coast FIRE Calculator.