Coast FIRE

How It Works

Normal FIRE requires you to accumulate your full FI number before stopping work. Coast FIRE splits the problem into two phases:

Phase 1 — The accumulation sprint. Invest aggressively early on. Get a lump sum into the market as fast as possible;

Phase 2 — The coast. Stop adding to investments. Let compound growth do the rest over decades. Work only enough to cover current expenses — no surplus required.

The math works because of time. A dollar invested at 25 has 40 years to compound before a traditional retirement at 65. At 7% annual growth, that dollar becomes roughly $15 by retirement. This means you need far less invested today than you'll need at retirement — because time does the heavy lifting.

The Coast FIRE Formula

Your Coast FIRE number is your full FI number discounted back to today at your expected rate of return.

The formula:

Coast FIRE number = FI target ÷ (1 + return rate)^years to retirement

Example:

• Full FI target: $1,500,000;
• Years to traditional retirement: 30;
• Expected annual return: 7%.

$1,500,000 ÷ (1.07)^30 = $1,500,000 ÷ 7.61 = $197,000

That's the number. If you have $197,000 invested at age 35 and never add another dollar, it will grow to $1,500,000 by age 65 at a 7% return. You've already won — you just haven't crossed the finish line yet.

Why This Matters So Much

Coast FIRE reframes the entire timeline in a way that makes financial independence feel accessible even to people who aren't on an extreme savings trajectory.

Consider two people:

Person A is pursuing full FIRE. They're saving 50% of income, living frugally, targeting retirement at 45. The plan is aggressive and requires years of intense discipline.

Person B hits their Coast FIRE number at 32 — say $150,000 invested. They shift gears. They stop needing to save beyond covering expenses. They take a job they enjoy more, even if it pays less. They travel more. They work part-time for a while. They're not "retired" by FIRE standards — but they're also not trapped. The portfolio will carry them to traditional retirement on its own.

Person B's life looks dramatically different from someone with no financial plan — and they achieved it without the extreme sacrifice of a full FIRE sprint.

Coast FIRE Numbers by Age

The younger you are, the smaller your Coast FIRE number — because you have more time for growth. Assuming a $1,500,000 FI target and 7% annual return:

The Emotional Shift Coast FIRE Creates

Reaching Coast FIRE changes your relationship to work in a specific and powerful way.

You are no longer working to build wealth. You are working to cover your life. The portfolio is already on autopilot. This removes enormous financial pressure from day-to-day decisions — you don't need a high salary anymore, you need a sufficient one. That distinction opens up career choices that would otherwise feel financially reckless:

• Leaving a high-stress corporate job for something meaningful but lower-paid;
• Starting a business with lower early income;
• Taking time off for family, health, or creative work;
• Moving somewhere cheaper without guilt;
• Working part-time.

None of these require full financial independence. They just require knowing that your long-term future is already funded.

The Key Risks to Understand

Coast FIRE assumes you don't touch the investments. The entire model depends on leaving the portfolio alone to compound. Withdrawing from it — for emergencies, lifestyle upgrades, or anything else — breaks the math. A robust emergency fund and strict separation of the coast portfolio from accessible savings is essential.

Market returns are not guaranteed. The 7% figure is a long-run historical average for diversified equity portfolios. Any given 30-year window will differ. Using a more conservative 5–6% estimate and recalculating gives a larger, safer Coast FIRE number.

Your FI target may change. If your lifestyle expenses rise significantly between now and retirement, your full FI number rises — and your Coast FIRE number was calculated against the old target. Recalculate every few years as life changes.

It only covers traditional retirement age. Coast FIRE doesn't give you the option to stop working at 40. It gives you the option to stop saving aggressively now, and still retire comfortably at 60–65. If earlier retirement is the goal, you need a higher Coast number or a shorter coast period.

Coast FIRE vs. Full FIRE

They're not mutually exclusive. Coast FIRE is often a milestone on the way to full FIRE. Many people:

1. Sprint aggressively to Coast FIRE first (achievable in 5–10 years for disciplined savers);
2. Exhale — loosen the budget, enjoy life more, take on less stressful work;
3. Continue investing at a gentler pace;
4. Arrive at full FI earlier than traditional retirement age, without the intensity of a pure FIRE sprint.

This hybrid approach is arguably the most psychologically sustainable path for most people. It breaks a decades-long goal into a nearer milestone, provides a genuine psychological reward when reached, and allows a more balanced life during the long middle stretch.

Key Takeaways

1. Coast FIRE is the point where compound growth alone will carry your portfolio to your full FI number — without another dollar of investment contributions;
2. The formula: FI target ÷ (1 + return)^years = your Coast FIRE number. The earlier you reach it, the smaller it is;
3. Once you've coasted, you only need to cover current expenses — no surplus saving required. This unlocks lower-stress, lower-paying, or more flexible work;
4. The biggest risk is touching the portfolio. The math depends entirely on leaving it alone to compound;
5. Coast FIRE and full FIRE aren't competing strategies — Coast FIRE is often the most achievable first milestone on the way to complete financial independence.