Coast FIRE is the point where your invested savings are large enough that compound growth alone will fund your retirement, even if you never contribute another dollar. After you reach it, you still work to cover today's expenses, but you no longer need to save for the future. Your money coasts the rest of the way.
It is the most achievable milestone on the path to financial independence, and for many people it arrives surprisingly early. This guide explains what Coast FIRE means, the simple formula behind it, real numbers by age, and how it compares to other types of FIRE. You can check your own figure any time with our free Coast FIRE calculator.
What is Coast FIRE?
FIRE stands for Financial Independence, Retire Early. Coast FIRE is one rung on that ladder. You reach it the moment your portfolio is big enough that, left untouched, it will grow into a full retirement nest egg by your target age. From that point on, retirement saving becomes optional. You only need to earn enough to pay your current bills.
The appeal is as much emotional as financial. Hitting your Coast FIRE number means the hardest part, building the base, is done. A 32 year old who has coasted can switch to a lower paying but more meaningful job, take a career break, or simply stop stressing about their retirement accounts, and still expect a fully funded retirement decades later.
How Coast FIRE works
Your financial life splits into two phases. In the first, you save aggressively to build a base. Once that base is big enough to coast, you enter the second phase, where you stop adding money and let compounding do the rest.
Because investment returns compound, money invested early does the heaviest lifting. A dollar invested at 30 has decades to double and double again before you reach 60. That is why the Coast FIRE number is far smaller than the full nest egg it eventually becomes.
The Coast FIRE formula
There are two steps. First, find the full nest egg you will need at retirement using the safe withdrawal rate rule:
target corpus = annual spending / withdrawal rateThen discount that target back to today using your expected real (after inflation) return over the years until retirement:
coast number = target corpus / (1 + real return) ^ (retirement age - current age)If your current investments already match the coast number, congratulations, you are coasting. If not, the gap tells you how much more to save before you can ease off.
A Coast FIRE example
Say you expect to spend 40,000 dollars a year in retirement and use a 4 percent withdrawal rate. Your target corpus is 40,000 divided by 0.04, which equals 1,000,000 dollars. With a 7 percent real return and 30 years to compound, money grows about 7.6 times over, so your Coast FIRE number today is roughly 1,000,000 divided by 7.6, or about 131,000 dollars. Invest that much now and, even if you never save again, you should reach 1,000,000 dollars by age 60.
Sample Coast FIRE number
$131,367
Age 30, retire at 60, $40k spending, 7% real return.
Coast FIRE number by age
The earlier you start, the smaller your Coast FIRE number, because compounding has more time to work. The table below assumes a 1,000,000 dollar target at age 60 and a 7 percent real return. Starting at 25 instead of 45 cuts the required sum to roughly a quarter.
| Start age | Years to grow | Growth multiple | Coast FIRE number |
|---|---|---|---|
| 25 | 35 years | 10.7x | $93,663 |
| 30 | 30 years | 7.6x | $131,367 |
| 35 | 25 years | 5.4x | $184,249 |
| 40 | 20 years | 3.9x | $258,419 |
| 45 | 15 years | 2.8x | $362,446 |
Coast FIRE vs other types of FIRE
Coast FIRE is often confused with Barista FIRE, and both differ from the more familiar Lean, Full, and Fat FIRE. Here is how they line up.
| Type | Savings needed | Still working? | Drawing from savings? |
|---|---|---|---|
| Coast FIRE | Enough that growth alone funds retirement | Yes, to cover today's costs | No, not yet |
| Barista FIRE | Partial | Part time, often for benefits | Sometimes, a small amount |
| Lean FIRE | A smaller full nest egg | Optional | Yes, frugal spending |
| Full FIRE | A full nest egg | Optional | Yes |
| Fat FIRE | A large nest egg | Optional | Yes, generous spending |
The key difference: Coast FIRE is about the portfolio being self sufficient for the future, while Barista FIRE is about reducing how much you work right now.
Is Coast FIRE realistic?
For people who start investing in their 20s or 30s, it is very achievable, because compounding has decades to work. That said, it rests on assumptions worth respecting.
- Returns vary. A weak stretch of returns early on can leave you short even if the long run average is fine.
- You must cover living costs. The plan assumes you do not touch investments after coasting. If you have to dip in, growth gets interrupted.
- Inflation and lifestyle creep. Your spending target should be in today's dollars and revisited as your life changes.
Treat your coast number as a confidence building checkpoint, not a finish line. Keep a margin of safety and recheck it every year or two rather than stopping contributions the instant you cross the line.
How to reach Coast FIRE faster
- Invest early and automatically, so your money gets the maximum number of compounding years.
- Capture every employer retirement match first, since it is an instant return on your contributions.
- Keep fees low with broad index funds, because costs compound against you just like returns compound for you.
- Lower your retirement spending target where you can, since a smaller target shrinks the number you need.
- Free up cash by trimming your biggest fixed costs. Our mortgage payoff calculator and paycheck calculators can help you see where the money goes.