Is the 4% Rule Still Safe in 2026?

The 4% rule has been the bedrock of FIRE planning for 25+ years. But rising stock valuations and evolving research raise an uncomfortable question: is 4% still safe for a 40-50 year retirement?

The Original Research vs. Today

Factor 1998 (Trinity Study) 2026
CAPE ratio (Shiller) ~25 ~40
10-year Treasury 5.5% ~4.2%
Retirement length studied 30 years 40-50 years (FIRE)
Bond yields High Low-moderate
Inflation 2-3% 2-3%

The original Trinity Study tested retirement horizons up to 30 years with mostly US-only data — a key reason modern research suggests lower withdrawal rates for longer FIRE retirements.

What Modern Research Says

Source Recommended SWR For
Morningstar (2024) 3.3-3.7% 30-year retirement
Big ERN (Early Retirement Now) 3.25-3.5% 60-year retirement
Kitces (ongoing) 3.5% floor, 4% with flexibility Dynamic withdrawals
Pfau (international data) 3-3.5% Global diversification

The New Consensus

For FIRE retirees targeting 40-50 year retirements:

  • 3.25%: Ultra-conservative, near-certain survival
  • 3.5%: The "new 4%" for long FIRE retirements
  • 4%: Still works if you have spending flexibility
  • 4.5%+: Requires dynamic withdrawal rules (Guyton-Klinger)

What This Means for Your FIRE Number

Annual Expenses FIRE at 4% FIRE at 3.5% FIRE at 3.25%
$40,000 $1,000,000 $1,143,000 $1,231,000
$60,000 $1,500,000 $1,714,000 $1,846,000
$80,000 $2,000,000 $2,286,000 $2,462,000

The difference between 4% and 3.5% is an extra ~$214K for $60K expenses — about 2-3 additional working years for most FIRE savers. These numbers are direct applications of the 25x rule at different withdrawal rates.

5 Strategies to Use a Higher Withdrawal Rate Safely

  1. Dynamic withdrawals: Cut spending in down years (Guyton-Klinger guardrails)
  2. Side income flexibility: Barista FIRE buffer of $10-20K/year
  3. Geo-arbitrage option: Move to LCOL if portfolio underperforms
  4. Bond tent: Increase bonds near retirement, then spend down
  5. Social Security/Pension floor: Count future guaranteed income

Bottom Line

The 4% rule isn't broken — but for 40+ year retirements, 3.25-3.5% is the safer play. If you have spending flexibility (can cut $10K in bad years), 4% still works. The best withdrawal strategy is one you'll actually follow.

Safe Withdrawal Calculator

Sources