[cpncrunch]

You would have it invested somewhere that generates a return above inflation.

[asdff]

Some of these calculators (maybe all?) assume this wad of money you retire with is stored under your mattress.

[Thorrez]

Any example of a calculator assuming it's stored under a mattress?

Here's[1] an article on the 4% rule, and it clearly is about invested money:

> The rule applies to a hypothetical portfolio invested 50% in stocks and 50% in bonds.

[1] https://www.schwab.com/learn/story/beyond-4-rule-how-much-ca...