The 4% rule offers ~90% likelihood of success for a 30-year retirement. If you retire at age 45, you'll need over 32 years' worth of funding for the average longevity. However, that means 50% of 45-year-olds will live beyond age 77.3 (for American males). This is why early retirees should not use the 4% rule.

In addition, dynamic withdrawal strategies such as the Guardrails Approach, allow you a safe initial draw of more than 5% for a 90% success likelihood for a 30-year retirement.