I'd find out the annual taxes in the area you are looking and divide by 12. I'd also use around $750 per year and divide by 12 for the insurance. This should give you a good idea. You then can add these numbers to your P and I payment (that you get from using a mortgage calculator on line). You will also have to figure in PMI (Private Mortgage insurance). This varies depending on if you do a conventional or FHA loan, how much you put down, your loan size, and your credit score ,etc. You could probably assume around $150 give or take.
Always feel free to call or email with any further questions.
I'd be happy to help.
Chad firstname.lastname@example.org 610-622-2212