Coast FIRE vs Lean FIRE vs Fat FIRE

The four flavours, at a glance

• Lean FIRE: ~$40,000/year spend, ~$1M portfolio at 4% withdrawal. Rural or LCOL, paid-off home, minimal travel.
• Regular FIRE: ~$60,000/year spend, ~$1.5M portfolio. Median US household lifestyle, modest travel.
• Fat FIRE: $150,000+ /year spend, $3.75M+ portfolio. HCOL retirement, generous travel, private healthcare bridge.
• Coast FIRE: enough invested by age 30–40 that compounding alone hits the retirement target by 65, without further contributions.
• Barista FIRE: a sibling of Coast, work part-time for healthcare and a smaller paycheck while the portfolio compounds.

Coast FIRE, in numbers

Coast FIRE is the easiest milestone to actually reach in your 30s. The math: if a $1.5M target at 65 is required, you only need roughly $250,000 invested by age 35, at a 7% real return, compounding alone delivers the rest. Once you cross the Coast threshold, you can technically stop saving and still retire on schedule.

The lifestyle payoff is enormous. Coast FIRE removes the pressure to maximise income or career trajectory. Many Coast achievers downshift to lower-paying but more meaningful work, teaching, art, nonprofit, freelance, while letting the portfolio do the heavy lifting. The trade is years of high savings up front for decades of optionality afterwards.

Lean FIRE, in practice

Lean FIRE requires both a low absolute spend ($30,000–$45,000/year) and discipline to maintain it. The portfolio target is achievable, roughly $750,000–$1.1M at a 4% withdrawal, but the lifestyle is constrained. Most Lean FIRE adherents live in low-cost states or abroad, drive paid-off used cars, and have either DIY or marketplace-subsidy healthcare.

Common Lean FIRE failure modes: medical surprises that aren't fully covered, lifestyle creep into the 50s, marrying or partnering with someone whose target is different, and inflation outpacing assumptions. Build the budget with at least 15% headroom over baseline spending to absorb the inevitable surprises.

Fat FIRE, in practice

Fat FIRE is for high earners targeting an above-median retirement lifestyle: $150,000+/year in spending, often in HCOL areas like San Francisco, New York or coastal California. The portfolio target is $3.75M–$5M+, plus a paid-off home and a bridge healthcare plan from early retirement to Medicare.

Fat FIRE typically requires 15+ years of $200,000+ household income and savings rates of 40–60%. The decisions get more nuanced, asset location, Roth conversion ladders, charitable giving via donor-advised funds, real-estate exposure beyond the primary home. Fat FIRE is the longest-horizon flavour but the most resilient against bad sequence-of-returns risk.

Picking your flavour

1. Audit your current spending honestly. Multiply by 25. That's your minimum portfolio if you change nothing.
2. Decide which lifestyle you actually want, the FIRE community's biggest mistake is over-optimising the number without imagining the life.
3. If your target spend is under $50,000 and you're geographically flexible, Lean is viable.
4. If your target is $60,000–$100,000 and you're median-income or above, Regular FIRE in 12–18 years is realistic.
5. If you're a high earner who wants HCOL freedom, Fat FIRE is a 15–20 year project with high savings rates.
6. If you've already built a meaningful nest egg in your 30s, Coast FIRE may already be available, calculate the breakpoint.

The four numbers, with worked targets

• Lean FIRE: $25,000–$45,000 annual spending, target portfolio $625k–$1.1M. Often single, often nomadic, low-cost geo-arbitrage.
• Regular FIRE: $40,000–$75,000 annual spending, target $1M–$1.9M. Standard middle-class lifestyle minus the commute.
• Fat FIRE: $100,000–$200,000+ annual spending, target $2.5M–$5M+. International travel, private school, healthcare cushion.
• Coast FIRE: contribute aggressively early, then stop and let compounding finish the job. A 30-year-old with $250k can stop saving and still hit $1.9M by 65 at 7% real returns.
• Barista FIRE: half-retirement, a low-stress part-time job covers current expenses while the portfolio grows untouched until traditional retirement age.

Coast FIRE math that actually works

Coast FIRE is the most achievable variant for middle-income earners. The formula: target_at_retirement / (1.07)^years_to_retirement. If you want $1.5M at 65 and you're 32, you need 1.5M / (1.07)^33 = ~$160,000 today, invested and never touched again. Continue working to cover current expenses, but every additional dollar saved is upside.

The leverage is in front-loading. Hitting Coast FIRE at 32 vs 42 is the difference between $160k and $315k, almost 2x, because you lose 10 years of compounding. The first decade of contributions is by far the most powerful, which is why FIRE communities push 'save 50% of income in your 20s' so hard.

What FIRE plans get wrong about healthcare and Social Security

Pre-65 healthcare is the single biggest FIRE risk. ACA subsidies are means-tested on AGI, keep AGI under 400% of the federal poverty line (~$83k for a couple in 2026) and a couple pays $400–$700/month. Above that, expect $1,500–$2,500/month for two adults. Build it into the spending number.

Social Security is not zero for early retirees. Even after 10–15 years of zero earnings, Social Security still pays, just less. A high earner who works 18 years and retires at 40 still receives roughly 60% of their full benefit at 67. Get a current Social Security statement (ssa.gov/myaccount) and include the projected benefit in your portfolio target math.

Picking the right flavour for your life

• Single, location-flexible, low-cost lifestyle: Lean FIRE works and the target is achievable in 10–15 years on a six-figure income.
• Couple with kids planning to stay in a HCOL city: Regular or Fat FIRE is more realistic; lean assumes a stripped lifestyle most families won't sustain.
• Started saving late or had a career interruption: Coast FIRE is the cleanest path, front-load until the milestone, then ease into a lower-stress career.
• Want flexibility but not full retirement: Barista FIRE removes job-loss anxiety while letting investments compound untouched.
• Run the math at choosefi.com or playingwithfire.co; the numbers are unforgiving but rarely surprising once you tally honest spending.

FIRE concepts worth knowing

• Savings rate, percentage of post-tax income invested; the single biggest driver of years to FI per Mr Money Mustache's classic chart.
• Withdrawal rate, annual portfolio withdrawal as % of starting balance; 4% is the FIRE baseline, 3.3–3.5% is recommended for early retirees.
• Geographic arbitrage, earning in HCOL, retiring in LCOL or abroad; can cut required portfolio by 30–50%.
• Sinking-fund pre-funding, building dedicated buckets for healthcare, home repairs and travel before retirement; smooths early-retirement spending shocks.
• Sequence-of-returns risk, magnified for FIRE retirees because of long horizons; managed via cash buffers and Guyton-Klinger guardrails.