Understanding DTI requirements

[Eric Knapp]

It is my understanding that to qualify for a conventional mortgage, banks generally have a 28/36 DTI limit, where front-end value of 28% is based on PITI, and back-end value of 36% based on total revolving debt.

First, is that understanding correct?

Second, If I have two mortgages already, one my home, the other a rental, and am seeking a third conventional mortgage for another rental, do both current mortgages get counted in the front-end figure, or is the rental mortgage only count back-end?