A house is the largest purchase most of us will ever make so it's important to calculate what your payment will be and how much you can afford.

The mortgage calculator will show you how much your monthly payment will be.

When you use the mortgage calculator, the main fields to keep your eye on are the interest rate and the length. If you input a lower rate, you can expect your monthly payment to go down. Just how much an interest rate decrease affects your monthly balance depends on the size of your loan.

Choose a loan with a shorter term, and you can expect your monthly payment to rise. Consider that you're paying off the same loan in a shorter period of time.

This quick overview is great for comparing lenders. It's the first step to finding a mortgage that matches your budget.