The general rule of thumb is that no more than one-third of your monthly gross income should go to your monthly mortgage payment. Your gross income is the total income before any deductions are made on your paystub.  Lenders also determine how much home you can afford by looking at a few key financial components that make up your financial portfolio, including your: Other monthly payment obligations Credit score Down payment amount   Using a mortgage calculator makes it easy to get a general idea of how much home you can afford by allowing you to enter in your down payment with current mortgage rates, estimated taxes, estimated insurance and HOA fees (if applicable), giving you an example of what you can expect to pay when it comes time to apply for a home loan.