Spending assumptions in this example
$55,000 is treated as the amount the portfolio must support each year. A useful spending estimate includes housing, food, transportation, insurance, health care, taxes paid from withdrawals, travel, repairs, and irregular expenses.
The figure should reflect the retirement lifestyle being planned, not automatically current income. Some costs may fall after leaving work while health care, travel, or taxes may rise.
How to interpret the withdrawal rate
The 4% rate is a planning assumption inspired by historical withdrawal research. It does not mean the portfolio earns 4%, and it does not guarantee that withdrawals will last for a particular retirement length.
Lower rates create larger portfolio targets. Higher rates create smaller targets but generally leave less room for weak returns, high inflation, fees, taxes, or a long retirement.
Important risks and limitations
This simple calculation does not model the order of market returns, changing spending, Social Security, pensions, taxes, investment fees, required distributions, or one-time expenses.
Use the result to compare scenarios and identify the assumptions that matter. Before relying on a retirement plan, consider a fuller cash-flow and withdrawal analysis.