A retirement projection can change even when you keep the starting balance, withdrawal amount, and return rate identical. I'll show how to audit the order of spending and investment growth, keep inflation adjustments consistent, and interpret the final row without mistaking a finite simulation for a guarantee.

I'm using a Vue calculator that produces a year-by-year table as the working example. The arithmetic is small enough to read in one sitting, but the labels need more care than the loop: a fixed-return scenario is not a forecast, and surviving a finite simulation is not the same as lasting forever.

Spend First, Then Grow What Remains

The inputs describe starting savings, a first-year annual withdrawal, an expected annual return, and inflation. Internally, percentage inputs become decimal rates. Savings and withdrawals must both be positive before the computed result returns a projection.

The central convention is that the withdrawal happens at the start of each year.…