Coast FIRE Explained: How to Stop Saving and Still Retire Rich

What Is Coast FIRE?

Coast FIRE is one of the most compelling milestones in personal finance — and one of the least understood.

Here's the core idea: if you invest enough money early enough, compound interest will grow your portfolio to your full retirement target without any additional contributions. You can stop saving for retirement, "coast" to the finish line, and simply cover your current living expenses with your income.

The name comes from the nautical concept of coasting — cutting the engine and letting momentum carry you forward.

Unlike traditional FIRE, which requires building a portfolio that covers all your expenses indefinitely, Coast FIRE only requires building enough of a foundation that time and compound interest do the rest of the work.

The Math That Makes Coast FIRE Work

The power of Coast FIRE is the power of compound interest given sufficient time.

Let's say you want a retirement portfolio of $1,500,000 at age 65. You're currently 35. You have 30 years for your investments to grow.

At an average annual return of 7% (a reasonable inflation-adjusted long-term estimate for a diversified stock portfolio), your money doubles roughly every 10 years.

• $187,500 invested at 35 → $1,500,000 at 65 (doubles 3 times over 30 years)
• $375,000 invested at 35 → $3,000,000 at 65
• $93,750 invested at 35 → $750,000 at 65

If you've already accumulated $187,500 in your investment accounts at age 35, you've technically reached Coast FIRE for a $1,500,000 target. You no longer need to make another retirement contribution — although continuing to invest will still accelerate your timeline or increase your final balance.

How to Calculate Your Coast FIRE Number

The Coast FIRE formula works backwards from your full FIRE number:

Coast FIRE Number = FIRE Number ÷ (1 + r)^n

Where:

• FIRE Number = your full retirement target (annual expenses × 25)
• r = expected annual return (as a decimal, e.g., 0.07 for 7%)
• n = years until traditional retirement age (or your target retirement age)

Example:

• Annual retirement expenses: $50,000
• Full FIRE number: $50,000 × 25 = $1,250,000
• Years until 65: 30 years
• Expected return: 7%

Coast FIRE Number = $1,250,000 ÷ (1.07)^30 = $1,250,000 ÷ 7.61 = $164,200

Once you've invested $164,200, your money will grow to $1,250,000 in 30 years at 7% returns — without any additional contributions.

Use our Coast FIRE Calculator to calculate your exact Coast FIRE number based on your age, target, and expected return.

Coast FIRE vs. Full FIRE: What's the Difference?

Coast FIRE is a waypoint, not the final destination — unless you're happy working indefinitely to cover expenses while your investments grow. It's also worth comparing with Barista FIRE, a related approach where part-time work covers living expenses while a partially-funded portfolio continues compounding.

Who Is Coast FIRE Best For?

Coast FIRE is ideal for several types of people:

Career changers: If you've saved aggressively in a high-paying career and want to transition to lower-paying, more meaningful work, Coast FIRE may already be your reality. Your investments are set; you just need enough income to live.

Parents: Many parents want to reduce work hours while raising children. If they've hit their Coast number, they can do this without derailing their retirement.

Burned-out professionals: High-stress industries like law, medicine, finance, and tech often create people who want out but feel financially trapped. Coast FIRE provides a clear exit ramp from the treadmill — you don't need to reach full FIRE before making a change.

Anyone who enjoys working: Some people love their work and have no desire to stop entirely. For them, the goal of full FIRE makes less sense. But reaching Coast FIRE means job loss, illness, or a career change won't derail their retirement security.

The Benefits of Coast FIRE

Freedom Without Full Independence

Coast FIRE gives you meaningful freedom long before you hit your full FIRE number. You can take a lower-paying job you love, move somewhere with lower cost of living, or work part-time — because you only need to cover today's expenses, not fund 50 years of retirement.

Reduced Financial Anxiety

Once you've hit Coast FIRE, the retirement question is essentially answered. You know that even if you stop contributing entirely today, you'll have sufficient funds in retirement. That's a profoundly calming realization.

Compounding Does the Heavy Lifting

The most powerful returns in compound interest happen in the later years. By reaching Coast FIRE early, you're capturing the most powerful phase of compounding — the decades of exponential growth — without needing to feed the portfolio further.

What Coast FIRE Doesn't Solve

Coast FIRE requires you to keep working to cover your current living expenses. If your expenses are high, or you live somewhere expensive, that's still a significant constraint.

It also doesn't protect against:

• Major medical expenses before traditional retirement age
• Loss of income if you can't find work that covers your expenses
• Lifestyle inflation that increases the amount you need to cover each year

The solution most Coast FIRE practitioners use: keep expenses reasonably controlled, maintain an emergency fund, and think of Coast FIRE as removing the retirement savings pressure — not as full financial independence.

Coast FIRE in Practice: A Real Example

Maria is 32, earns $72,000/year, and has $145,000 saved across her 401(k) and Roth IRA. She wants to retire at 65 with $1,800,000 (to cover $72,000/year at 4%).

Her Coast FIRE calculation:

• FIRE number: $1,800,000
• Years to 65: 33
• Expected return: 7%
• Coast FIRE Number = $1,800,000 ÷ (1.07)^33 = $1,800,000 ÷ 9.32 = $193,100

Maria has $145,000 — she's close but not quite there. At her current savings rate of $1,500/month, she'll hit $193,100 in roughly 17 months.

After that, she doesn't need to save another dollar for retirement. She could leave her high-stress corporate job, take a part-time role that covers her $4,200/month expenses, and let her $193,000 grow into $1,800,000 over the following 33 years.

That's the power of Coast FIRE.

Your Next Steps

1. Find your full FIRE number using our FIRE Calculator
2. Calculate your Coast FIRE number with our Coast FIRE Calculator
3. Compare your current portfolio to your Coast FIRE number — you may be closer than you think
4. Read about the different types of FIRE to understand how Coast FIRE fits into the broader FIRE landscape
5. Understand your savings rate to see how quickly you'll reach your Coast number

Coast FIRE is often the most achievable near-term FIRE milestone — and hitting it changes how you think about your relationship with work forever.

This article is for educational purposes only and does not constitute financial or investment advice. Investment returns are not guaranteed. Consult a qualified financial professional for guidance specific to your situation.