FIRE Path Comparator: Lean / Regular / Fat / Coast / Barista / Geo-Arb Side by Side

Why "FIRE" needs to be plural

Most FIRE calculators give you one number: your portfolio target. That's useful but it answers the wrong question. The real question for most people isn't "how big does my portfolio need to be?" — it's "which version of financial freedom am I optimizing for, and what are the trade-offs?" Lean FIRE on $750K vs Fat FIRE on $2.25M vs Coast FIRE that frees you from saving by age 40 are three different lives, not three points on the same curve.

The 6 paths in this tool aren't exhaustive (Slow FIRE, HENRY FIRE, mini-retirements all exist) but they cover the canonical set that has the most distinct math. The point isn't to pick the "right" one — it's to see all six on the same screen so you can have an informed conversation with yourself about which trade-offs you actually want.

How the math works

1. Annual savings = income − spending. Capped at 0 if spending exceeds income.
2. Each path's portfolio target = target annual spending × 25 (Trinity Study 4% withdrawal rate). The 6 paths differ only in what they assume "target annual spending" is: Lean fixes it at $30K, Regular = current, Fat = 1.5× current, Geo-Arb = current × 0.55, Barista = current × 0.50, Coast = current (same as Regular).
3. Years to reach each target: solve future-value-with-contributions for n. With S = current savings, A = annual contribution, r = real return: target = S·(1+r)ⁿ + A·((1+r)ⁿ − 1)/r.
4. Coast FIRE special case: iterate ages from now to your target age. Find the earliest age X where your current trajectory's balance ≥ (Regular FIRE number ÷ (1+r)^(target − X)). At that age, you can stop saving entirely; compound interest carries you the rest of the way.
5. Fastest path identification: highlight whichever of the 6 has the shortest years-to-reach. Often this is Lean or Geo-Arb.

Sources: Trinity Study (Cooley/Hubbard/Walz 1998) for the 4% withdrawal rate, Bengen 1994 for the original SAFEMAX research, Robert Shiller's dataset for the historical 6.5-7% real US stock return, ChooseFI and Mr. Money Mustache's blogs for the Lean/Coast/Barista taxonomy.

What this simplifies: single real-return assumption (Monte Carlo would model the distribution), no Social Security or pension (those reduce the required portfolio dollar-for-dollar against spending — see our FIRE Calculator for full simulation), no taxes during accumulation (modeled implicitly via real return), no healthcare-cost modeling for Barista FIRE (assumes part-time work covers it), flat returns each year (no sequence-of-returns risk in years-to-FIRE estimate).

Math runs locally. Your income and savings never leave the browser. Source on github.

Where this comparison doesn't apply cleanly

• Slow / phased FIRE. A gradual transition (75% work → 50% → 25%) doesn't have a single "number" — it's a strategy that overlaps accumulation and retirement years. See the pillar guide for how to think about it.
• High-income early career (HENRY). The implicit assumption that "your real return is 5%" understates the front-loading effect for someone going from 30% savings rate to 60% as their income jumps in their late 20s and 30s. The tool's estimate becomes accurate again 5-10 years into the high-saving period.
• Significant pension or Social Security expected. Pensions and Social Security reduce your portfolio target dollar-for-dollar against spending. A $25K/yr pension cuts a $1.5M Regular FIRE number down to $900K (= ($60K − $25K) × 25). This tool doesn't subtract them; the FIRE Calculator does.
• Barista FIRE without realistic part-time work. Barista FIRE assumes you can reliably earn 50% of your spending from part-time work that also provides healthcare. In practice, healthcare-providing part-time jobs are rare. Validate that this is true for your industry before committing to the strategy.
• Geo-Arb without honest cost research. The default 55% multiplier reflects moderate-cost European or Latin American spots. Actual cost varies wildly: rural Mexico ~35%, Lisbon ~55%, mid-tier US states like Tennessee ~75%, premium destinations like Singapore could exceed 100%. Research your specific destination with current data, not the headline cost-of-living index from 2018.

What to actually do with this

1. Run YOUR specific numbers — actual current savings, actual current income, actual current spending. Not approximations.
2. Look at the gap between Lean and Fat FIRE for your inputs. If it's enormous (e.g., 8 yrs vs 25 yrs), the spending lever is your most powerful one. If it's narrow (e.g., 12 yrs vs 15 yrs), focus on income/savings rate instead.
3. For Coast FIRE specifically: notice how the "coast age" can be 10-15 years before Regular FIRE age. This is the most under-appreciated path — it doesn't require permanent austerity, just a strong saving sprint upfront.
4. If Geo-Arb is dramatically faster than other paths, that's signal you live in an expensive market. The decision to move isn't just about the math — but the math should be on the table.
5. Save a snapshot. Re-run in 6 months. The "how much faster did I get to my chosen path?" number is the actual progress metric for your financial life.