Laws prevent lenders from making home loans that exceed 35% of your monthly income. The general rule of thumb is to not exceed 28% of your gross monthly income, according to Forbes. To figure out what that looks like for your circumstances, set up a budget that includes housing costs as a line item, along with other monthly bills and regular living expenses. You'll also want to factor in things like homeowners insurance, any homeowners association (HOA) fees and home maintenance costs.