What is Coast FIRE?

Coast FIRE is a milestone on the way to early retirement. You reach it when the money you have already invested will grow, on its own, to your full FIRE number by the time you want to retire, without you adding another cent to retirement savings.

After that point you still work to cover today's bills, but you can stop saving for retirement. Compounding takes it from here. For a lot of people that unlocks a lower-stress job, fewer hours, or simply breathing room, years before full financial independence.

How Coast FIRE works

Compounding does the heavy lifting, and money invested early has the most time to do it. A dollar invested in your twenties has decades to double and double again, so the contributions you make early matter far more than the ones you make later.

Coast FIRE is the moment your invested balance is finally large enough that growth alone, with no new contributions, will reach your full FIRE number by your target retirement age. Once you are there, you have bought your future retirement. The rest is just letting it ride.

How to calculate your Coast FIRE number

Your Coast FIRE number is your full FIRE number discounted back to today, using the return you expect and the years until you retire. The formula is: Coast number = FIRE number divided by (1 + r) raised to the number of years, where r is your expected real (after-inflation) return.

Say your FIRE number is $1,000,000, you are 30, you want to retire at 65 (35 years away), and you assume a 5% real return. That is 1,000,000 divided by 1.05 to the 35th power, which is about $181,000. With roughly $181,000 invested at 30, compounding alone gets you to $1,000,000 by 65 at that return.

The number is very sensitive to the return you assume and your timeline. A lower assumed return, or fewer years until retirement, means a bigger Coast number. Treat it as an estimate, not a promise, because real returns vary year to year.

Start earlier, coast on less

Coast number for a $1,000,000 goal at 65, assuming a 5% real return. The earlier you start, the smaller the amount that can coast the rest of the way:

Invested at 25 (40 yrs to grow): $142,000
Invested at 30 (35 yrs to grow): $181,000
Invested at 35 (30 yrs to grow): $231,000
Invested at 40 (25 yrs to grow): $295,000
Invested at 45 (20 yrs to grow): $377,000

Coast FIRE vs Barista FIRE vs full FIRE

Full FIRE. Your investments can cover all of your living expenses, so you can stop working entirely. This is the finish line.
Coast FIRE. Your investments are on track to reach that full number by retirement age on their own, so you can stop saving for retirement. You still work to cover today's expenses.
Barista FIRE. Part-time or lower-stress work covers part of your expenses and your portfolio covers the rest. It sits between Coast and full FIRE.

How to find your Coast FIRE number

Compound Joy is a free tool that tracks the Coast FIRE milestone alongside Lean, FIRE, and Fat FIRE. Enter your spending, accounts, and target retirement age, and it shows your Coast number and how close you are, using the same compounding math above. No account or payment needed to start.

Find your Coast number

Frequently asked questions

What is the difference between Coast FIRE and FIRE?

Full FIRE means your investments can cover all of your living expenses, so you can stop working entirely. Coast FIRE is an earlier milestone: your investments are on track to reach that full number by retirement age on their own, so you can stop saving for retirement, but you still work to cover today's expenses.

How do I calculate my Coast FIRE number?

Take your target FIRE number and discount it back to today using your expected real return and the years until retirement: Coast number = FIRE number / (1 + r) raised to the number of years. For example, a $1,000,000 goal at age 65, starting at 30 (35 years) at a 5% real return, is about $181,000 today.

Is Coast FIRE realistic?

It depends heavily on the return you assume and how many years you have. The earlier you start, the smaller your Coast number, because compounding has more time to work. It is an estimate rather than a guarantee, since real returns vary from year to year.

Can I still retire early with Coast FIRE?

Coast FIRE on its own targets a normal retirement age, because it relies on decades of growth. To retire early you would still need to cover the gap years, either by saving more to reach full FIRE or by working part-time, which is closer to Barista FIRE.

This is background information, not financial advice. The Coast FIRE figures use a 5% real-return assumption and standard compounding; your own number depends on your situation and the return you assume. See the glossary for the terms used here.