Is the mortgage factored into NOI on the BP Rental Calculator?

[Brandon Hunsaker]

I was using the BP Rental Calculator to analyze an owner occupied rental property. My NOI came out much higher than I expected. I noticed that when I calculated the numbers manually I could get the same NOI if I left out the monthly mortgage expenses of "principal & interest". Why is the "principal & interest" of a mortgage not calculated in the expense portion of an NOI calculation?