The mortgage payment calculator is an online tool that can calculate your monthly mortgage installment, but that is not the only calculation this tool can do. Although finding your monthly installment would be one of the primary numbers you would want to find out even before applying for a loan, there are other numbers that can be just as useful to know.  For example, the total interest you mortgage calculators will pay on the property, because although you may be excited that the installment is low and within your limits, you might be disappointed if you end up paying double the amount for the property. The online tool can give you that answer. Based on that, you may change your mind and decide to increase the installment by dropping the duration of the loan and hence also dropping the overall interest, or may choose to keep on the lookout for a lower interest rate either now or later on when you can have the option to remortgage.