Coast FIRE is a financial milestone where you have saved enough money in investment accounts that compound growth alone — with no further contributions — will grow your portfolio to a full retirement target by a traditional retirement age like 65. After reaching Coast FIRE, you no longer need to save for retirement. You still need to earn enough to cover your current living expenses, but any job that covers the bills will do, even if it pays much less than your current career.

How do you calculate your Coast FIRE number?

Start with the portfolio you want at retirement (for example, $1,500,000 at age 65). Then calculate how much you would need invested today so that compound growth at an assumed real return (typically 6-7% after inflation) reaches that target by 65. The younger you are, the lower the number — because there are more years of growth ahead. For example, at a 7% real return, a 25-year-old needs about $150,000 to coast to $1,500,000 by 65, while a 40-year-old needs about $400,000 for the same target.

What is the biggest risk of Coast FIRE?

The biggest risk is the return assumption. Coast FIRE relies on compound growth at a specific rate (often 7% real return) for decades. If actual market returns are lower — due to a prolonged bear market, changing economic conditions, or simply bad luck with timing — your portfolio may not reach the target. This risk is higher for Coast FIRE than traditional FIRE because there are no ongoing contributions to cushion the impact of poor returns. Continuing to save even modestly after hitting Coast FIRE provides a meaningful safety margin.

Coast FIRE — VaporCalc Learn

What Is Coast FIRE?

Coast FIRE is a milestone, not a destination. It's the point where you've saved enough in investment accounts that compound growth — with no additional contributions — will carry your portfolio to a full retirement target by a traditional retirement age like 65.

After Coast FIRE, you don't need to save another dollar for retirement. You still need income to cover day-to-day expenses (rent, food, insurance), but any job that pays the bills will do. You could switch to part-time work, take a lower-paying job you enjoy more, freelance, or start something new. The retirement savings pressure is off.

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Key Concept

The Coast FIRE number. The amount you need invested today so that compound growth alone reaches your retirement target by your chosen retirement age. It depends on three variables: (1) your target portfolio at retirement, (2) your assumed annual real return (after inflation, typically 6-7%), and (3) how many years you have until retirement. The younger you are, the lower the Coast FIRE number — because compound growth has more years to work.

The Math Behind Coast FIRE

Here's a concrete example. Suppose you want $1,500,000 at age 65 (enough to withdraw $60,000/year at a 4% rate). You assume a 7% real return (after inflation). How much do you need invested today at different ages?

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Key Concept

The compound growth assumption. Coast FIRE relies on the idea that money invested in a diversified portfolio of stocks and bonds grows at a long-term average rate — often cited as 7% after inflation for a stock-heavy portfolio. This is a historical average, not a guarantee. Actual returns in any given decade can be significantly higher or lower. The longer your time horizon, the more likely your actual returns will approximate the average — but "more likely" is not "certain."

Coast FIRE numbers by current age, targeting $1,500,000 at age 65, assuming 7% real return
Current Age	Years to 65	Coast FIRE Number
25	40	~$100,000
30	35	~$140,000
35	30	~$197,000
40	25	~$276,000
45	20	~$388,000
50	15	~$544,000

Look at the 25-year-old column: $100,000 invested and left alone for 40 years at 7% real return grows to roughly $1,500,000. That's the power of compound growth over long time horizons. At 40, you need almost three times as much because there are 15 fewer years of compounding.

Coast FIRE Growth Projection

Current Age 30

Current Savings $100,000

Target at 65 $1,500,000

Coast FIRE number at age 30: $197,000 · You need $97,000 more

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Real-World Scenario

Sam is 28 with $95,000 in a 401(k) and Roth individual retirement account (IRA). Sam's retirement target is $1,500,000 at age 65 — enough to withdraw $60,000/year. At a 7% real return with 37 years of growth, Sam needs about $120,000 to coast. Sam is $25,000 away. With current savings of $1,200/month, Sam will hit the Coast FIRE number in about two years. After that, Sam could switch from a stressful corporate job to something more fulfilling that just covers monthly expenses — even if it pays 40% less.

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Real-World Scenario

Maya is 42 with $310,000 in retirement accounts. Her target is $1,500,000 at 65. At 7% real return with 23 years of growth, she needs about $310,000 to coast — she's essentially already there. Maya has been pushing herself to save $2,500/month in a demanding career. Realizing she's hit Coast FIRE, she takes a position at a nonprofit that pays $20,000 less per year but has better hours and work she cares about. She stops contributing to retirement accounts and uses the income difference for current-life quality. Her existing portfolio grows on its own.

What Changes at Coast FIRE

Once you've hit Coast FIRE, several things shift:

Job flexibility. You can choose work based on interest, hours, location, or stress level rather than salary. As long as it covers your bills, the retirement savings are handled.
Reduced financial pressure. No more mandatory 401(k) contributions, no more "I have to save X this month." The retirement savings engine is running on autopilot.
More money for now. Dollars that were going to retirement can go to current-life spending — travel, hobbies, experiences, or paying down a mortgage.
Lower stress ceiling. Losing a high-paying job is less catastrophic when retirement savings are already handled. Any replacement job just needs to cover current expenses.

Coast FIRE vs Full FIRE

Coast FIRE and full FIRE (Financial Independence, Retire Early) solve different problems:

Full FIRE means your portfolio covers all expenses right now. You can stop working entirely. This requires 25 times your current annual expenses saved and invested.
Coast FIRE means your portfolio will cover retirement expenses eventually (at age 65), but you still need earned income for current expenses. You can't stop working — you just don't need to save anymore.

Coast FIRE is typically reachable much earlier than full FIRE. A 30-year-old might hit Coast FIRE with $140,000 invested but need $1,000,000+ for full FIRE. That's a big difference, and for many people, the lifestyle changes available at Coast FIRE are more valuable than waiting another decade or more for full independence.

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Myth vs Reality

Myth: "Once I hit Coast FIRE, I can stop caring about money entirely."

Reality: Coast FIRE removes the retirement savings obligation, but you still need to earn enough to cover current expenses — housing, food, health insurance, transportation, taxes. If you quit your job without a plan for covering those costs, you'll start drawing down the portfolio you were supposed to let grow. Coast FIRE also assumes a specific return rate for decades into the future. Staying aware of your portfolio's progress and having a backup plan (like the ability to resume saving if returns lag) keeps Coast FIRE viable.

The Risk: Return Assumptions

Coast FIRE's biggest vulnerability is the return assumption. The entire concept relies on your portfolio growing at a certain rate for a long time. If you assume 7% and reality delivers 5%, your $140,000 at age 30 grows to about $835,000 by 65 instead of $1,500,000. That's a significant shortfall.

Ways to manage this risk:

Use a conservative return assumption. Calculating with 5-6% real return instead of 7% gives you a larger (more cautious) Coast FIRE number.
Keep saving a little. Even modest ongoing contributions ($200-$500/month) after hitting Coast FIRE build a meaningful buffer over decades.
Check in periodically. Review your portfolio annually. If actual growth is lagging the assumption, you can resume saving before it's too late to catch up.
Think of Coast FIRE as a milestone, not a finish line. It's a point where the pressure drops, not where you stop paying attention.

Practical Steps

Set your retirement target. Decide what annual spending you want in retirement and multiply by 25. That's the portfolio you're aiming for at age 65 (or your chosen retirement age).
Calculate your Coast FIRE number. Use the formula: Coast Number = Target ÷ (1 + return rate)^years. Or just use the calculator below — it does the math for you.
Track your progress. Compare your current invested balance to the Coast FIRE number. As your investments grow and you age, the gap closes from both sides (your balance rises, and the required number rises because you have fewer years of growth remaining).
Decide what you'd change. Before you hit Coast FIRE, start thinking about what you'd do differently if you only needed to cover current expenses. Would you switch careers? Go part-time? Move to a lower-cost area? Having a plan makes the transition concrete rather than theoretical.

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Try It Yourself

Open the Coast FIRE Calculator. Enter your current age, target retirement age, current portfolio balance, and desired annual spending in retirement. See if you've already hit Coast FIRE — or how close you are. Try adjusting the return assumption between 5% and 7% to see how sensitive the number is. Then check your 401(k) projections to see if your current contribution rate is on track.

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If you found out today that your retirement savings were fully on track and you no longer needed to save, what would you change about your work life? Would you stay in your current job? Pursue something different? The answer tells you a lot about whether you're working because you want to or because you feel you have to.

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Key Takeaways

Coast FIRE means you've saved enough that compound growth alone will reach your retirement target — you no longer need to save, just cover current expenses.
The younger you are, the lower the Coast FIRE number. A 25-year-old targeting $1.5M at 65 may need only ~$100,000 invested today (at 7% real return).
Coast FIRE is reachable much earlier than full FIRE and opens up job flexibility, lower stress, and more spending on current life.
The main risk is the return assumption. If actual market returns fall short, the portfolio won't reach the target. Use conservative estimates and check in annually.
Coast FIRE is a milestone on the path, not a finish line. Even modest ongoing savings provide a meaningful buffer.