Coast FIRE Calculator

What Is Coast FIRE?

Coast FIRE is the moment your invested money becomes self-sufficient. You have enough in your retirement and investment accounts that, even if you never contribute another dollar, compound growth alone will grow it into your full financial independence number by the time you retire. You have not reached that number yet, but you are on an unstoppable trajectory toward it. The word “coast” captures the idea perfectly: you have done the hard pedaling early, and now you can take your feet off the pedals and let momentum carry you the rest of the way. Reaching Coast FIRE does not mean you can stop working — you still need income to cover today’s rent, groceries, and bills — but it does mean you can stop saving for retirement. That single shift unlocks enormous flexibility.

Coast FIRE vs Traditional FIRE vs Barista FIRE

These three milestones sit on the same road but at different distances. Traditional FIRE is the finish line: you have accumulated roughly 25 times your annual expenses, so you can withdraw about 4% a year and never work again. It is the largest number and usually the last one you reach. Coast FIRE is the earliest of the three. You hit it the moment your existing balance is large enough to grow into that full FIRE number on its own — often decades before you actually get there. In between sits Barista FIRE, a hybrid where your investments cover most of your expenses but you still work a low-stress or part-time job (the name comes from taking a coffee-shop job partly for the health benefits) to bridge the gap and delay tapping your portfolio. Coast FIRE and Barista FIRE both trade a smaller nest egg for earlier freedom; the difference is that Coast FIRE only requires you to cover your current expenses, while Barista FIRE assumes your portfolio is already chipping in.

The Math Behind the Coast FIRE Number

The Coast FIRE number is simply your future FIRE target discounted back to the present at your expected real return. Because compound growth is exponential, a fixed target in the future translates into a much smaller number today. The further away retirement is, the more time compounding has to work, and the smaller that present-day number becomes.

Suppose you want a $1,000,000 portfolio at age 60, you are 30 today, and you assume a 7% real return. Over 30 years, (1.07)³⁰ equals about 7.61, so your Coast FIRE number is $1,000,000 ÷ 7.61, or roughly $131,400. If you already have that much invested, you are coasting. If you have $100,000, you are about 76% of the way there and need to invest around $31,400 more before compounding can take over. This is the same exponential engine explored in our compound interest calculator, and if you are still building the balance through regular contributions, our SIP calculator shows how monthly investing gets you to the coast number faster.

Why the Real Return Assumption Matters

No single input changes your Coast FIRE number more than the return you assume. Because the calculation compounds that rate over decades, a one-point difference snowballs. In the example above, dropping from a 7% to a 5% real return shrinks the growth factor from 7.61 to about 4.32, which raises the amount you need today from roughly $131,400 to about $231,700 — a swing of $100,000 driven by two percentage points. That sensitivity is why the assumption deserves care.

Always use a real, inflation-adjusted return rather than a headline nominal one, since your FIRE target is stated in today’s money. A diversified, stock-heavy portfolio has historically delivered around 7% after inflation over long periods, but the future is never guaranteed and sequences of poor years happen. A sensible approach is to run the calculator twice: once with an optimistic 7% and once with a conservative 4% to 5%. If you are comfortable with both numbers, you have built in a margin of safety. Treating the lower figure as your real target protects you from being lulled into stopping too early by a rosy assumption.

What to Do Once You’re Coasting

Hitting Coast FIRE is less an ending than a permission slip. Because your retirement is effectively funded, the money you were pouring into investments is suddenly free for other uses. Many people use that freedom to change how they work: switching to a lower-paying job they enjoy more, cutting back to part-time, taking a sabbatical, or starting a business without the pressure of a big salary. Others redirect the freed-up cash toward nearer-term goals such as a home down payment, their children’s education, or travel, since the long-term account no longer needs feeding.

A few habits keep Coast FIRE durable. Re-check your number at least once a year, because a market drop can push your balance back below the coast line and a strong run can build a comfortable surplus. Keep your investments broadly diversified and low-cost so your real return has the best chance of matching your assumption. And keep an eye on the bigger picture — track all of your assets and liabilities with our net worth calculator so you can see the full trajectory, not just the retirement slice. Coast FIRE turns retirement from a decades-long obligation into a solved problem, letting you spend your working years on the things that actually matter to you.