What is Coast FIRE?

Coast FIRE is the point in your financial journey where you have saved enough money that compound investment growth alone will carry your portfolio to your full retirement number by a target age -- without a single additional dollar contributed. Once you hit your Coast FIRE number, the math is on your side. You can stop saving entirely and simply let your existing investments compound over the remaining years until retirement.

This is a powerful milestone because it fundamentally changes your relationship with work. You no longer need to maximize income or chase promotions for the purpose of saving. You only need to earn enough to cover your current living expenses. That opens up options that were previously off the table: switching to a lower-paying but more fulfilling career, going part-time, taking a sabbatical, starting a business, or moving to a lower cost-of-living area. The pressure to save disappears because the saving is already done.

The concept works because of the exponential nature of compound interest. A dollar invested at age 25 does far more work than a dollar invested at age 45, because it has 20 additional years to compound. Coast FIRE takes advantage of this by front-loading your savings early in your career when compounding has the longest runway. The earlier you start, the less total money you need to invest, and the sooner you can coast.

Coast FIRE vs Regular FIRE vs Barista FIRE

The FIRE movement has spawned several variations, each representing a different balance between savings, work, and lifestyle. Understanding the differences helps you pick the right target for your situation.

Coast FIRE sits between the intensity of full FIRE and the flexibility of Barista FIRE. You do not need as much money as full FIRE because you are not retiring immediately -- you are letting time and compounding close the gap. And unlike Barista FIRE, you do not need to draw from your portfolio at all during the coast phase, which means your investments grow uninterrupted.

How Coast FIRE is Calculated

The Coast FIRE calculation works backward from your full FIRE number. First, determine how much you need at retirement: your annual expenses divided by your safe withdrawal rate. Then, discount that number back to today using the real rate of return (nominal return minus inflation). The result is how much you need invested right now so that compound growth alone will reach your FIRE number by your target retirement age.

In this example, a 30-year-old who has $262,000 invested today can stop contributing entirely and still expect their portfolio to grow to $1,000,000 by age 65, assuming a 7% nominal return and 3% inflation. If they already have more than $262,000, they are past Coast FIRE and could shift to a lower-income lifestyle immediately.

The Power of Starting Early

Age is the single most powerful variable in the Coast FIRE equation. Every additional year of compounding dramatically reduces the amount you need saved today. A 25-year-old needs to save roughly 30% less than a 30-year-old to hit the same Coast FIRE number, and a 30-year-old needs about 40% less than a 40-year-old. This is not a linear relationship -- it is exponential, which means the early years of saving matter disproportionately.

Consider two people who both want $1,000,000 at age 65 with a 4% real return. The 25-year-old needs about $208,000 today. The 35-year-old needs about $308,000. The 45-year-old needs about $456,000. Each decade of delay requires roughly 50% more capital. This is why financial advisors emphasize starting early -- even small amounts invested in your 20s have an outsized impact on your retirement readiness decades later.

This does not mean Coast FIRE is only for young people. A 40-year-old with $300,000 saved and $40,000 in annual expenses has a Coast FIRE number of roughly $385,000 for a retirement age of 65. They may only need a few more years of saving to cross the threshold. The key is running the numbers for your specific situation rather than assuming it is too late.

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