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Reach FI · flavor math

FIRE Number by Flavor — Lean vs Regular vs Fat

Generic calculators multiply your spending by 25 and stop. That number silently assumes a 30-year retirement, one withdrawal rate for every budget, pre-cliff ACA subsidies, and Social Security that starts the day you quit. This one uses a flavor-specific withdrawal band (a lean budget has no slack to cut, so it gets the conservative band), adjusts the multiple for your horizon, itemizes the restored 2026 ACA 400% FPL cliff per flavor, and subtracts Social Security as a present value on the portfolio side.

HHS FPL · asOf 2025-01 Rev. Proc. 2025-25 · asOf 2025-07 KFF SLCSP · asOf 2026-01 FRED TIPS · asOf 2026-07 SSA Trustees · asOf 2025-06 Updated 2026-07-06

Assumptions

live · all three flavors as ranges
Bare-bones budget. Default = BLS lowest-quintile average ($35,046, 2024).
Default = BLS all-household average ($78,535, 2024).
Comfort budget. Default = BLS highest-quintile average ($150,342, 2024).
From your SSA statement (ssa.gov/myaccount). Household total if two earners.
Sets the horizon, the ACA years (to 65), and the premium age rating.
Horizon = plan-to age − retirement age. Longer horizons shave the withdrawal band.
62–70. Years between retirement and claim are the bridge you self-fund.
Sets the federal poverty line your MAGI is measured against.
Marketplace-covered adults
Adults on the benchmark (second-lowest-cost silver) plan, age-rated at your retirement age.
Early-retiree MAGI is usually below spending (basis withdrawals aren't income). Drives the subsidy and the cliff.
Blended federal + state on gross withdrawals; grosses up the annual need.
Set your inputs to project all three flavor numbers as ranges.
$—
Lean — Fat — ■ —
Regular number (typical) Low–high band across the horizon
Every output is a range, not a point. A lean budget has no discretionary slack to cut in a bad sequence, so it gets the conservative withdrawal band; the same 4% rule does not apply to lean and fat alike.

Lean vs Regular vs Fat

low · typical · high per flavor

Lean — conservative band, no discretionary slack to cut in a drawdown:

Regular — just under the classic 4% anchor:

Fat — discretionary spending can flex down, so the band runs higher:

Coral = optimistic end (high withdrawal rate, full Social Security), aqua = typical, mint = conservative end (low rate, TIPS-30 discount, Trustees 77% payable haircut).

ACA line item, per flavor

2026 law · enhanced credit expired 2025-12-31
FlavorMAGI vs FPLNet premiumStatus
Lean———
Regular———
Fat———

For 2026 the 400% FPL cliff is back: $1 of MAGI over the line forfeits the entire premium tax credit — typically a five-figure annual jump for a fat budget. Congress may still act retroactively; treat every subsidy figure as a projection contingent on legislation.

Formula correction — the PV(SS) bug

regular flavor, typical assumptions
— Shortcut (spend − SS) / SWR
— Corrected: need/SWR − PV(SS)
— Correction (understated by shortcut)
— Pre-claim bridge (self-funded)

The shortcut nets Social Security out of spending as if the check starts the day you retire. It doesn't — the benefit's present value is subtracted from the portfolio side, and the years before claim age are a bridge you fund yourself.

Methodology & sources
Show the math ›
Set your inputs to see the worked numbers for each flavor.
Assumptions & sources ›
AssumptionValueSource · asOf
Withdrawal band — lean 3.25–3.5% (50-yr anchor) Early Retirement Now, SWR Series — 60-yr historical failsafe at 75–100% equity · asOf 2026-07 · lean budgets get the conservative band: no discretionary room to cut
Withdrawal band — regular / fat 3.7–4.0% / 4.0–4.25% Bengen (1994), J. Financial Planning — SAFEMAX 4.15% at 30 yrs, 50/50 · asOf 2026-07 · fat's discretionary share can flex down in a bad sequence
Horizon adjustment +0.5pp at 30 yrs … −0.2pp at 60 yrs Bengen 30-yr vs ERN long-horizon spread (~0.7–0.9pp), interpolated · 25× is a 30-year multiple; 45-yr retirements land nearer 28–31×
Poverty line (FPL) $15,650 + $5,500/person (hh 1) HHS ASPE 2025 guidelines, 48 states + DC — applies to coverage year 2026 per IRC §36B(d)(3)(B) · asOf 2025-01
Applicable percentage & cliff 2.10–9.96% of MAGI; no credit ≥400% FPL IRS Rev. Proc. 2025-25 (original §36B schedule restored — enhanced PTC expired 2025-12-31) · asOf 2025-07 · legislative uncertainty flagged
Benchmark premium (SLCSP) $625/mo national avg, age 40 KFF marketplace benchmark premiums 2026, rescaled on the CMS default age curve (21/40/64 = 1.000/1.278/3.000) · asOf 2026-01 · illustrative — real SLCSP is rating-area-specific
PV(Social Security) discount 2.0–2.75% real FRED TIPS constant-maturity real yields — DFII10 2.25%, DFII30 2.78% · asOf 2026-07-01 · CPI-indexed stream discounts at a real yield
Benefit payable share (conservative end) 77% of scheduled SSA 2025 OASDI Trustees Report — OASI reserve depletion 2033, continuing income covers 77% · asOf 2025-06
Spending defaults $35,000 / $78,500 / $150,000 BLS Consumer Expenditures 2024 — lowest quintile $35,046, mean $78,535, highest quintile $150,342 · asOf 2024 · defaults only, user-editable
Pre-65 healthcare treatment carried across the whole horizon conservative proxy for lifetime healthcare — Medicare premiums + out-of-pocket after 65 are not separately modeled (v1)

Formula: required = (spending + withdrawal tax + pre-65 ACA premium) ÷ withdrawal rate − PV(Social Security). The benefit's present value is subtracted from the portfolio side — putting it in the numerator is the classic bug this page corrects. Under-100%-FPL MAGI assumes expansion-state Medicaid at $0; in non-expansion states a coverage gap can apply. Every output is an estimate shown as a range.

Written by Author to be finalized before launch · Updated 2026-07-06

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