Your mortgage size is determined by three factors; your mortgage payment, the interest rate, and the amortization period. Once you calculate the size of your monthly payment you can use the other two variables to figure out just how much you can borrow.
Your time-frame for repayment and the interest rate you get make a huge difference in the amount you can borrow and how much it will ultimately cost you in interest payments. I explain how these factors work to determine how big a mortgage you can get in the video below.