What Is Coast FIRE? How to Calculate Your Number and When You Can Stop Contributing

Coast FIRE is the savings milestone where your existing portfolio will grow to your full Financial Independence number by retirement — without you contributing another dollar. Coast FIRE ≠ traditional FIRE. You still work, but only enough to cover living expenses. Your investments do the heavy lifting.

To find your Coast FIRE number:

1. Multiply your target annual retirement spending by 25 to get your FI Number
2. Divide your FI Number by (1 + your expected annual return) raised to the power of years until retirement
3. If your current savings meet or exceed that result, you have hit Coast FIRE and can stop making retirement contributions

What Is Coast FIRE?

Traditional FIRE requires saving aggressively until your portfolio is large enough to fund full retirement indefinitely. You reach your FI Number — typically 25× your annual spending — then stop working entirely, living off 4% annual withdrawals. The math works, but the accumulation phase is relentless: high savings rates, decade-long timelines, and sustained lifestyle sacrifice.

Coast FIRE is a different calculation. You save aggressively until your portfolio hits a specific threshold — the coast number — then you stop making retirement contributions completely. Your existing balance compounds on its own. You still work, but your job only needs to cover monthly living expenses. There is no financial pressure to save beyond that.

The name comes from the sailing metaphor: once you reach the coast threshold, you cut the engine and let the wind carry you. Compound interest is the wind. A 38-year-old with $241,600 invested at 7% annual return will reach $1.5 million by age 65 with zero additional contributions. The math requires only patience, not continued sacrifice.

Who finds Coast FIRE appealing? Primarily burned-out high earners who have saved well but feel trapped by their career. Professionals in demanding fields — law, finance, medicine, tech — who have been maximizing retirement contributions for a decade and want an exit from that pressure. People who want to do meaningful, lower-paid work: teaching, nonprofit management, freelancing, small business ownership. Coast FIRE unlocks that transition without requiring you to wait until you have the full FI Number.

The core insight is that time compounds more aggressively than additional contributions once your balance is large enough. Below a certain threshold, contributions matter more than returns. Above it, returns matter more than contributions. The coast number is where that crossover happens.

The Coast FIRE Formula

The formula works backward from your target FI Number:

Coast FIRE Number = FI Number ÷ (1 + annual return)^years to retirement
FI Number = Annual spending × 25

Step-by-step example:

1. Target annual spending in retirement: $60,000
2. FI Number = $60,000 × 25 = $1,500,000
3. Years to retirement (retire at 65, current age 38): 27 years
4. Assumed return: 7% per year
5. Coast FIRE Number = $1,500,000 ÷ (1.07)^27 = $1,500,000 ÷ 6.21 = $241,600

The math is present-value discounting applied to retirement planning. You are asking: how much money, invested today, will grow to $1.5 million in 27 years at 7% return? The answer is $241,600. If you have that amount saved right now, every retirement contribution from this point forward is optional, not required.

The diagram above shows two lines: your portfolio growing with monthly $500 contributions (blue), and the Coast FIRE threshold declining as you get closer to retirement (green dashed). The crossover at age 44 is where portfolio value first exceeds the threshold — contributions made before that point drove the portfolio past the coast number. After the crossover, even without contributions, the blue line continues upward on its own.

Coast FIRE Numbers by Age

How much you need saved right now to coast to $1.5M by age 65, at two different return assumptions:

Notice how the coast number approximately doubles for each decade you wait. A 30-year-old needs $143,000; a 40-year-old needs $277,000 — nearly double. A 50-year-old needs $543,000 — nearly double again. Reaching coast FIRE early is dramatically cheaper, which is why front-loading savings in your 30s pays outsized returns.

A Real-World Example

Imagine you are 38 years old with $280,000 saved across a 401(k) and IRA. You are in a well-paying but exhausting job. The question: do you need to keep maxing out retirement accounts?

Walk through the math:

1. Target annual retirement spending: $60,000/year
2. FI Number: $60,000 × 25 = $1,500,000
3. Years to retirement (retire at 65): 27 years
4. Coast FIRE Number at age 38: $1,500,000 ÷ (1.07)^27 = $241,600

At $280,000 already saved, you have exceeded your Coast FIRE number by $38,400. You could stop contributing to retirement accounts today — completely stop — and your existing $280,000 would grow to approximately $1.66 million by age 65 at 7% return, well past the $1.5 million target.

What does this mean in practice? It means you can:

• Take the lower-paying but less stressful role you have been eyeing
• Reduce to four days a week
• Leave the corporate job for nonprofit or teaching work
• Start a business that pays less but gives you more autonomy

The only financial constraint is that your job still needs to cover monthly living expenses. You are no longer required to save for retirement. That shift — from “I must save 20% of my income every month” to “I just need to cover my bills” — is the psychological core of Coast FIRE. It converts every career decision from a financial necessity into a lifestyle choice.

What Can You Do After Reaching Coast FIRE?

Three paths that Coast FIRE practitioners commonly take:

1. Barista FIRE

Take a part-time or lower-stress job specifically to cover monthly living expenses. Many Coast FIRE practitioners work in service roles — cafes, bookstores, national parks — or do consulting, freelancing, or seasonal contract work. The income requirement is modest because the savings burden is gone. A couple needing $5,000/month in living expenses can often cover that with a single part-time income between them, especially if they have paid off their mortgage or relocated to a lower cost area.

2. Semi-retirement

Stay in your field but move to a lower-intensity role. The business development director becomes a project manager. The senior engineer goes back to individual contributor work. The high-earning lawyer joins a nonprofit legal clinic at a fraction of BigLaw pay. Income drops, but so does stress — and your financial plan can absorb the income cut because you no longer need to fund retirement contributions alongside living expenses.

3. Geographic arbitrage

Move to a lower cost-of-living area where your income covers expenses more easily. The freelancer earning $65,000 per year in San Francisco who relocates to Tucson or Albuquerque suddenly has a dramatically different financial picture. Lower housing, food, and transportation costs mean the same income goes much further — and Coast FIRE only requires covering living expenses, not building savings.

The psychological shift across all three paths is the most valuable outcome. When you are working by choice rather than by financial necessity, your relationship with your career changes completely. Difficult projects become tolerable. Unreasonable managers lose their leverage. You can negotiate from a position of genuine optionality because your retirement is already funded. This quality-of-life benefit is worth real money — most Coast FIRE practitioners describe it as more impactful than any salary increase they ever received.

How Inflation Affects Your Coast FIRE Number

The standard Coast FIRE formula uses a nominal return of 7%. But inflation erodes purchasing power — $60,000 in today's dollars will not buy $60,000 worth of goods in 27 years.

If you want $60,000 per year in today's purchasing power and you are 27 years from retirement, your actual spending target in 2053 dollars at 3% inflation is $60,000 × (1.03)^27 ≈ $133,000 per year. That inflates your FI Number to $133,000 × 25 = $3,325,000 — more than double the nominal figure.

However, your investment returns also compound nominally, so the cleanest solution is to use your real return — nominal return minus inflation — in the Coast FIRE formula directly. This way both the target and the growth rate are expressed in the same inflation-adjusted terms.

• Nominal return: 7%
• Inflation: 3%
• Real return: approximately 4% (technically (1.07 ÷ 1.03) − 1 = 3.88%)

Using a 4% real return for the same 27-year horizon produces a coast number of $1,500,000 ÷ (1.04)^27 = approximately $515,000. That is more than double the nominal-return estimate of $241,600. The conservative rule of thumb: use a real return of 4–5% (7% nominal minus 2–3% inflation) for Coast FIRE math to ensure your target is expressed in real purchasing power.

The difference between the 4% and 6% real return estimates — $515,000 versus $342,000 — is a $173,000 swing driven entirely by one percentage point in assumptions. This is why return sensitivity is the first risk category to understand before downshifting your income.

Coast FIRE vs Lean FIRE vs Traditional FIRE

These four strategies differ primarily in how much you save before stopping, and whether you plan to work afterward:

Coast FIRE occupies a practical middle ground. You reach financial safety much earlier than traditional FIRE — a decade or more earlier in many cases — but you accept that you will continue earning an income to cover expenses. For people who want meaningful work anyway, this trade-off is not a compromise. It is the ideal structure.

The Risks in a Coast FIRE Plan

1. Sequence of returns risk in accumulation

A prolonged bear market in the years immediately after you stop contributing can materially delay your coast timeline. A 40% drawdown — similar to 2000–2009 — cuts a $280,000 portfolio to $168,000, pushing it below the coast threshold even if you had already hit it. The conservative fix: target 10–15% more than your calculated coast number as a buffer. If the math says $242,000, aim for $275,000 before downshifting. You can also plan to resume modest contributions if a significant drawdown occurs — coast FIRE is not an irrevocable commitment to zero savings.

2. Healthcare before 65

The most under-modeled cost in any early retirement plan. Health insurance through an employer typically costs the employee $150–300 per month. Individual coverage on the ACA marketplace for a 45-year-old non-smoker can cost $500–1,200 per month depending on income and location — that is $6,000–$14,400 per year in premiums alone, before deductibles. Coast FIRE practitioners who step down to part-time or lower-wage work often lose employer coverage entirely. See the healthcare gap between early retirement and Medicare at 65 before finalizing your coast plan — it is the one expense that derails more coast plans than any market downturn.

3. Lifestyle creep

If your spending rises from $60,000 to $80,000 per year — a reasonable 33% increase over 15 years — your FI Number grows from $1.5M to $2.0M. Your coast number at age 38 grows from $241,600 to $322,000. If you downshifted at $280,000 expecting to coast to $1.5M, you now need to either resume contributions or accept a lower retirement income. Recalibrate your coast math every two to three years as your spending patterns evolve.

4. Return assumption sensitivity

Going from 7% nominal to 5% real return changes the coast number by 70–115% depending on time horizon. A one-percentage-point difference in assumed returns can mean the difference between “I have hit coast FIRE” and “I need four more years of contributions.” Run your coast calculation at both a base case (7% nominal) and a conservative case (4–5% real return) and make decisions based on the range, not a single number.

Key Takeaways

• Coast FIRE is the point where your current portfolio will grow to your full FI Number by retirement with zero additional contributions
• The formula discounts your retirement target back to present value: FI Number ÷ (1 + return)^years to retirement
• A 38-year-old targeting $60K/year in retirement needs approximately $241,600 saved today at 7% nominal return — or $515,000 at 4% real return
• Use a real return of 4–5% (nominal return minus inflation) for a conservative, inflation-adjusted coast calculation
• Once you hit the number, every career decision becomes a choice about time and meaning rather than financial survival — the most significant psychological shift in personal finance

Use the Free Coast FIRE Planner

Frequently Asked Questions

Is Coast FIRE a real retirement strategy or a compromise?

It is both — and deliberately so. Coast FIRE is a conscious trade-off: you work longer (to fund living expenses) but with far less financial pressure. The appeal is psychological: once you have hit your coast number, every career decision becomes a choice about time and meaning rather than financial survival. Many Coast FIRE practitioners describe it as the most freeing financial milestone they have hit — more impactful than any salary increase. The people it does not work for are those who genuinely want to stop working entirely as soon as possible, for whom traditional FIRE remains the better target.

What if my investments lose value after I stop contributing?

This is sequence-of-returns risk, and it is real. A 30% drawdown the year after you hit coast FIRE pushes your crossover date back. The conservative fix: aim for 10–15% more than your calculated coast number as a buffer. If your math says $240,000, aim for $270,000 before you downshift. Also consider that coast FIRE assumes you will eventually increase contributions if the market falls significantly — you are not locked in. The commitment is psychological (permission to downshift), not contractual.

Can I reach Coast FIRE inside a 401(k)?

Yes, and it is the most common way. Your 401(k) and IRA balances count toward your Coast FIRE number regardless of where the money is held. The only relevant constraint is that you cannot access 401(k) money before age 59½ without penalty, with a few exceptions (Rule 72(t) substantially equal periodic payments, for example). Since Coast FIRE still assumes you are working to cover living expenses, early withdrawal is rarely necessary — you are not trying to live off the portfolio yet. The tax-advantaged compounding in a 401(k) makes it the single most efficient vehicle for reaching the coast threshold.

What happens to my Coast FIRE number if I want to retire at 60 instead of 65?

It rises significantly because you have fewer years of compounding. Using the same formula at 7% return: retiring at 60 from age 38 gives you 22 years of compounding, not 27. If your coast number for retiring at 65 is $241,600, then for retiring at 60 it is $241,600 × (1.07)^5 ≈ $338,700 — about 40% higher. Every five years earlier you want to retire raises your coast threshold by roughly (1.07)^5 ≈ 40%, compounding quickly for aggressive early retirement targets.

Should I count home equity toward my Coast FIRE number?

No — at least not the equity in your primary residence. You need somewhere to live in retirement, which means you cannot liquidate that equity to fund spending without also solving a housing cost problem. Equity in rental properties, REITs, or a second home you explicitly plan to sell in retirement can count. Focus the coast calculation on liquid, investable assets: 401(k), IRA, taxable brokerage accounts, and HSA balances. Everything else is a separate calculation.

Once you have confirmed you have hit your coast number, the next calculation most people overlook is healthcare. See what early retirement healthcare actually costs before downshifting — it is the one expense that can derail even a well-funded coast plan.

Ready to run your own numbers? Open the Coast FIRE Planner to find your exact crossover date based on your current savings, contribution rate, and target retirement income.