I am trying to simulate some market returns for a retirement investment
portfolio.

I have the PMT function working well.

example:

want income of $250,000, for 32 years, 3% withdraw rate, overall
portfolio value (PV) is $5,097,000.

This is only an estimate- the purpose was to find the aprox value of an
investment portfolio which would yield $250k of income.

On another spreadsheet I was trying to calculate an ammortization table
to know how much principal and how much interest makes up the
$5,100,000.

My confusion is with the NPER and PER inputs- what do these mean? Is
one the 32 years and the other which of the 32 years it's calculating?