CoastFIRE

CoastFIRE is the variant of [FIRE](FireMovement) that asks a different question. Traditional FIRE asks: "How fast can I accumulate 25x my expenses?" CoastFIRE asks: **"How much do I need to save before I can stop saving and let compound growth do the rest?"**

The answer is usually less than you think — and much less than full FIRE — because time and compounding are doing the heavy lifting. The trade-off: you don't retire early. You continue working, but you work on your terms — lower stress, lower pay, more meaning — because every dollar you earn goes to current expenses, not to building a retirement portfolio.

How CoastFIRE Works

The Core Concept

1. Save aggressively for a compressed period (typically 5-15 years) early in your career

2. Accumulate a "CoastFIRE number" — enough that compound growth alone will reach your full retirement target by age 60-67

3. Stop saving for retirement entirely

4. Work in any capacity that covers your current living expenses — no savings required

5. At traditional retirement age, your portfolio has grown to a full FI number without any further contributions

The Math

The CoastFIRE number depends on three variables:

- **Target retirement portfolio** (your FI number at retirement age)

- **Expected real return** (typically 5-7% after inflation)

- **Years until traditional retirement**

Formula: CoastFIRE Number = Target Portfolio / (1 + real return)^years

CoastFIRE Numbers by Age

Assuming a target of $1,500,000 at age 65 (supporting ~$60,000/year at 4%):

|-------------|------------|---------------------------|---------------------------|

| 25 | 40 | $213,000 | $100,000 |

| 28 | 37 | $246,000 | $122,000 |

| 30 | 35 | $271,000 | $140,000 |

| 33 | 32 | $314,000 | $172,000 |

| 35 | 30 | $347,000 | $197,000 |

| 38 | 27 | $402,000 | $242,000 |

| 40 | 25 | $443,000 | $277,000 |

| 45 | 20 | $565,000 | $388,000 |

| 50 | 15 | $721,000 | $543,000 |

A 30-year-old who has saved $271,000 in retirement accounts can — mathematically — stop saving entirely. If they continue working to cover current expenses and the market returns an average 5% real, they'll have $1.5M at 65.

At a 7% real return (closer to US equity historical average), the numbers are even more forgiving. A 25-year-old needs only $100,000.

Adjusted for Different Target Spending

CoastFIRE numbers at age 30, 5% real return:

| Target Annual Spending | Target Portfolio (25x) | CoastFIRE Number at 30 |

|-----------------------|-----------------------|-----------------------|

| $40,000 | $1,000,000 | $181,000 |

| $50,000 | $1,250,000 | $226,000 |

| $60,000 | $1,500,000 | $271,000 |

| $80,000 | $2,000,000 | $362,000 |

| $100,000 | $2,500,000 | $452,000 |

The Appeal of CoastFIRE

1. Front-Loading Pain, Back-Loading Freedom

Traditional FIRE requires maintaining a high savings rate for 10-20 years. CoastFIRE concentrates the sacrifice into a shorter, more intense period — often your early-to-mid 20s when expenses are naturally lower (no children, smaller housing needs, higher risk tolerance).

A 22-year-old earning $65,000 who saves $25,000/year for 8 years (including employer matches and growth) can realistically accumulate $250,000-$300,000 by age 30 and then coast.

2. Career Flexibility in Your Prime Years

Once you've hit your CoastFIRE number, every job only needs to cover current expenses. This opens up options that traditional career-track thinking forecloses:

- Leave a high-paying but stressful corporate role for a lower-paying non-profit position

- Start a business without the pressure of needing it to fund retirement

- Work part-time to prioritise parenting, caregiving, or creative work

- Take extended sabbaticals (a few months off between jobs) without retirement savings anxiety

- Move to a lower cost-of-living area and take a commensurate pay cut

The common thread: your income only needs to cover today's bills. Tomorrow's retirement is already funded.

3. Psychological Safety

Knowing that your retirement is funded — even if you can't touch it for decades — provides a foundation of financial security that changes how you experience work. Being laid off is stressful but not catastrophic. A bad manager is a problem to solve, not an existential threat. The power dynamic between employee and employer shifts when retirement isn't at stake.

4. More Achievable Than Full FIRE

Full FIRE requires 25x current expenses, often $1M-$2M+. CoastFIRE requires $200K-$400K for someone in their late 20s to early 30s. This is ambitious but achievable for a broader range of incomes — particularly for those who start early.

Worked Example: Maya's CoastFIRE Journey

**Maya, age 23**, graduates with a computer science degree earning $85,000/year.

**Phase 1: The Sprint (Ages 23-30)**

|------|-----|--------|---------|--------------------|

| 1 | 23 | $85,000 | $30,000 | $32,000 |

| 2 | 24 | $90,000 | $33,000 | $68,000 |

| 3 | 25 | $95,000 | $35,000 | $108,000 |

| 4 | 26 | $100,000 | $38,000 | $153,000 |

| 5 | 27 | $105,000 | $40,000 | $203,000 |

| 6 | 28 | $110,000 | $42,000 | $257,000 |

| 7 | 29 | $115,000 | $44,000 | $316,000 |

*Savings include 401(k) contributions, employer match, Roth IRA, and taxable brokerage. Assumes 7% returns during accumulation.*

At age 29, Maya has $316,000. Her CoastFIRE number for $60,000/year spending at 65 (at 5% real return) is $271,000. **She's past her CoastFIRE number.**

**Phase 2: The Coast (Ages 30-65)**

Maya leaves her corporate software job. She:

- Becomes a freelance developer working 25 hours/week, earning $55,000/year

- Moves from San Francisco to Portland, cutting her living expenses to $45,000/year

- Saves nothing additional for retirement

- Has $10,000/year surplus for travel, hobbies, and an emergency fund

Meanwhile, her $316,000 portfolio grows untouched:

| Age | Portfolio (5% real) | Portfolio (7% real) |

|-----|--------------------|-----------------------|

| 30 | $316,000 | $316,000 |

| 35 | $403,000 | $443,000 |

| 40 | $515,000 | $621,000 |

| 45 | $657,000 | $871,000 |

| 50 | $839,000 | $1,222,000 |

| 55 | $1,071,000 | $1,714,000 |

| 60 | $1,367,000 | $2,404,000 |

| 65 | $1,745,000 | $3,371,000 |

At the conservative 5% real return, Maya has $1.75M at 65 — supporting $70,000/year at 4%. At the optimistic 7%, she has $3.37M. Either outcome funds a comfortable retirement, all from savings she made before age 30.

CoastFIRE and Account Structure

CoastFIRE introduces a specific account challenge: if most of your savings are in tax-advantaged accounts (401(k), IRA), you can't access them penalty-free until 59.5. This is fine for CoastFIRE — you're working until 60-65 anyway — but it means your savings are locked during the coast phase.

**Optimal account split for CoastFIRE:**

| Account | Purpose During Coast | Purpose at Retirement |

|---------|---------------------|----------------------|

| 401(k)/Traditional IRA | Grows untouched | Primary retirement income |

| Roth IRA | Emergency reserve (contributions withdrawable anytime) | Tax-free retirement income |

| Taxable brokerage | Optional buffer for career transitions | Flexible access before 59.5 |

See [Account Type Strategy](AccountTypeStrategy) for the full framework. During the sprint phase, maximise tax-advantaged space; during the coast phase, your only financial concern is covering current expenses.

Criticisms of CoastFIRE

CoastFIRE has its own set of vulnerabilities beyond the general [FIRE criticisms](FireMovement).

Criticism 1: It Assumes Consistent Real Returns

The entire model rests on compound growth averaging 5-7% real over 30-40 years. While US equities have historically delivered this, it is not guaranteed.

**The sensitivity problem:**

| Real Return | $300K at 30 → Value at 65 |

|------------|---------------------------|

| 3% | $845,000 |

| 5% | $1,659,000 |

| 7% | $3,202,000 |

| Historical US average (~6.5%) | $2,735,000 |

The difference between 3% and 7% real return is a factor of 3.8x. A sustained low-return environment (as Japan experienced from 1990-2020) could leave a CoastFIRE follower with far less than planned.

**Mitigation**: Use conservative assumptions (5% real or lower). If your CoastFIRE number works at 5%, a 7% reality gives you abundance. If you optimistically plan at 7% and get 4%, you're short.

Criticism 2: Inflation in Spending Is Ignored

CoastFIRE plans target future portfolio value based on today's spending. But spending changes — children, housing upgrades, healthcare costs as you age, caring for elderly parents. The $60,000 budget at 30 may become $80,000 at 45 even in real (inflation-adjusted) terms due to lifestyle changes.

**Mitigation**: Target a higher spending level than you currently need, or plan to resume modest saving if spending increases.

Criticism 3: The "Coast" Job May Not Have Benefits

Lower-stress, part-time, or freelance work often lacks employer benefits — particularly health insurance and retirement plan access. In the US, this means:

- ACA marketplace premiums (manageable with income-based subsidies)

- No employer 401(k) match (forgoing free money, though by definition CoastFIRE doesn't need additional savings)

- No employer-funded disability or life insurance

See [Medicare Planning and Healthcare](MedicarePlanningAndHealthcare) for the healthcare dimension.

Criticism 4: You're Betting on Your Future Self

CoastFIRE assumes you'll continue working in some capacity for 25-35 more years. Health problems, disability, caregiving responsibilities, involuntary job loss, or industry disruption could eliminate your ability to earn. Unlike full FIRE (where the portfolio covers everything), CoastFIRE requires ongoing income for current expenses.

**Mitigation**: Maintain [disability insurance](DisabilityInsurance) during the coast phase. Keep marketable skills current. Build an emergency fund beyond the retirement portfolio.

Criticism 5: Social Security Is Reduced

Social Security benefits are based on your highest 35 years of earnings. A CoastFIRE person who earns $100K for 8 years and then $55K for 25 years will have a noticeably lower benefit than someone who earned $100K+ for 35 years. Those zero-earning or low-earning years pull the average down.

**Practical impact**: Maybe $500-$800/month less in Social Security at 67 compared to a full career at higher earnings. Over a 25-year retirement, this is $150,000-$240,000 in lost guaranteed income.

**Mitigation**: Factor reduced Social Security into your target portfolio. The CoastFIRE portfolio needs to compensate for the lower guaranteed income floor. See [Social Security Claiming Strategy](SocialSecurityClaimingStrategy).

Criticism 6: It's Psychologically Difficult to Stop Saving

People who have the discipline to save $30,000-$40,000/year in their 20s often find it psychologically impossible to stop. The habit that got them to CoastFIRE makes the "coast" phase anxiety-inducing. Many CoastFIRE adherents report continuing to save "just a little" — which defeats the purpose.

This isn't a flaw in the strategy but in the execution. It's worth noting because the psychological dimension is often underestimated.

CoastFIRE vs. Other FIRE Variants

|-----------|----------|-----------|-------------|----------|

| Retirement age | 35-50 | 60-67 | 40-55 (partial) | 35-50 |

Who Should Consider CoastFIRE

CoastFIRE is best suited for people who:

1. **Start early** (20s) — the math works dramatically better with 35-40 years of compounding

2. **Want career flexibility, not full retirement** — you love working but hate the pressure

3. **Have realistic spending expectations** — you've honestly assessed future costs

4. **Can handle the psychological shift** — stopping saving after years of intense accumulation

5. **Have a plan for healthcare** — employer coverage through coast-phase work, or ACA

CoastFIRE is poorly suited for people who:

1. Start after 40 — insufficient compounding time

2. Have volatile or uncertain income in planned coast-phase career

3. Are using 7%+ return assumptions without modelling the downside

4. Have no emergency fund beyond the retirement portfolio