FI number calculation 101 question..

You are correct that it depends. You definitely want to leave out the savings part, since that is an expense only while you are approaching retirement. The mortgage is a bit trickier. You can leave it and calculate your FI number with it in (just know that you will be overshooting a bit). You can also use one of the simulators that allows you include different streams of expenses and cash flows over time (like this housing expense ending in 10 years, kid1 college expenses starting in 4 years, kid2 college expenses starting in 7 years, social security income starting in 27 years, etc). But if you are calculating your FI number for the first time, you probably don't need that level of detail. Just leave the mortgage payment in and use the resulting FI number as your "ballpark", then refine it as time goes on.