Turn a withdrawal rate into annual cash flow and portfolio stress scenarios
The 4% rule is a historical withdrawal framework, not a guarantee that a portfolio will last for a specific retirement.
How to read the result
A higher starting withdrawal improves near-term spending but generally increases sensitivity to longevity, inflation, and early market losses.
Practical scenario: Compare several starting rates and a flexible-spending case instead of treating 4% as a universal answer.
What the estimate does not include
A constant-return model cannot capture full sequence-of-returns risk; use stress testing and cash-buffer planning as well.
Treat the result as a range for further verification, then check the original contract, financial institution, or responsible authority before making a material financial decision.