What is Coast FIRE?
Coast FIRE is the point at which your existing investment portfolio, left untouched, will compound to your full FIRE number by traditional retirement age — without any additional contributions. Once you hit your Coast FIRE number, you only need to earn enough to cover your current expenses. You can stop aggressive saving and let compounding do the rest.
For example, if you need $1,200,000 to retire at 65 and you are 35, your money has 30 years to grow. At a 7% annual return, you need roughly $157,000 invested today for it to grow to $1,200,000 by 65. That $157,000 is your Coast FIRE number at 35.
What is Full FIRE?
Full FIRE means building a portfolio large enough to cover your spending now — you no longer need to work at all. Full FIRE is a cleaner end state, but it usually requires a longer accumulation phase and a larger portfolio target. The timeline depends on income, savings rate, market returns, and annual spending.
Why Coast FIRE appeals to many people
Coast FIRE is often appealing when you want more flexibility before fully retiring. Key reasons people target it first:
- Work flexibility — you can shift to lower-stress, part-time, or creative work without abandoning long-term independence.
- Reduced financial anxiety — traditional retirement is fully funded regardless of what happens next.
- Optionality — you can keep saving aggressively to reach full FIRE sooner, or ease off.
- Portfolio insurance — even if something derails aggressive saving, the base is already secured.
Many people find that reaching Coast FIRE dramatically reduces financial anxiety even while they are still working. Knowing that traditional retirement is funded is meaningful insurance.
How to calculate your Coast FIRE number
The formula: Coast FIRE number = FIRE target ÷ (1 + annual growth rate)^years to retirement.
Using the example above: $1,200,000 ÷ (1.07)^30 = $157,000. The variables are your full FIRE target, assumed annual return, and how many years until you want to stop working. A lower growth rate assumption or earlier target retirement age raises the Coast FIRE number.
Which path is right?
The right path depends on your timeline, expenses, job flexibility, and how much optionality you want along the way. Coast FIRE is often the first achievable milestone on the way to Full FIRE — tracking it as a stepping stone can make a long FIRE journey feel more manageable.