Lenders look at a variety of factors when evaluating how much mortgage you can afford. These include your monthly mortgage payment as a percent of your gross (pre tax) income, and your total debt loan including your mortgage payment relative to your gross income.
Another determining factor is the loan-to-value (LTV) ratio, meaning the amount borrowed relative to the appraised value of the property. Higher LTVs represent a higher risk to lenders. Lenders can provide qualification details for various types of mortgages, including Federal Housing Administration (FHA) and Veterans Administration (VA) loans.
Most mortgage payments comprise: principal, interest, tax, and homeowners insurance (PITI). Don't forget to consider other expenses beyond PITI, including mortgage insurance, home maintenance expenses, homeowners association fees, and utilities.