You can get a useful first estimate by comparing dependable income with expected spending, then asking how much of the remaining gap your savings must carry. It is not a promise. It is a fast way to find out whether the idea is plausible, tight, or plainly premature.
The four numbers that matter first
Start with expected monthly spending, dependable monthly income, investable savings, and the number of years until you want to stop working. The difference between spending and dependable income is the gap your portfolio must support.
That gets us to a useful first answer. Taxes, inflation, health costs, debt, market risk, and the timing of Social Security can move the result, but we do not need to hide the first answer behind all of them.
What a responsible answer sounds like
It should sound like: ‘At your current spending level, the plan looks workable but not roomy,’ or ‘The gap is too large unless one of three things changes.’ It should not sound like certainty about the next thirty years.
A deeper plan is useful when the decision is close, when income changes over time, or when a bad early market could do real damage. But depth should improve the answer—not be the toll booth you pass through to hear it.
- A retirement answer based only on account value
- Spending estimates that ignore taxes or health costs
- A plan that assumes one smooth investment return every year
A rough answer today is better than a perfect plan you never receive. Use the rough answer to decide whether the next layer of work is worth doing.