You can do it either way as long as you understand the method you are using. I will call them method 1 and method 2. Method 1 is not adding your bet in and method 2 will be adding your bet in.
Method 1: Example is 1200 pot and we face 400 to call. Our
pot odds are 1200/400 which is 3 so we are getting 3 to 1 on our money. For us to break even we have to win 1 out of 3+1 times meaning we have to win 1 out of 4 times. It is 1 out of 4 and not 1 out of 3 because if we call and we win then the pot moved our way is 1600 (1200+400 (our call)) so 1 out of 4 times is breaking even. If that example is confusing think of a coin flip where you betting 1 and win 2 (1 dollar you bet and win an additional 1 dollar) if you pick heads or tails correctly (even money bet). Even money is considered 1/1 but to break even on this bet we can lose one time and win the next time so we need to win 1 out of 2 times and not 1 out 1 time. When using method one you need to understand the idea that whatever the pot odds are you have to add 1 to the 1 out of how many times I need to win to break even.
Method 2: In this method you add your bet into the pot so in the previous example you would be calling 400 into the 1200 pot so our pot odds are 400 to win 1600 (including the bet with this method) so we are 4 to 1. Here since you already added your calling bet into the calculation you do not need to add the 1 to get the number of times you need to win to break even. It would just be whatever the calculation comes out to so in this case its a simple 1600/400 or 4 to 1.