Mortgage calculators are available to help you determine how much mortgage money you can afford, and the amount of your monthly payments.
The Loan Application
You will be asked to provide detailed financial information when you apply for a mortgage. Be prepared with the following information.
Purchase agreement 
Funds for appraisals, credit reports and lending fees
12 months cancelled rent/mortgage checks
W-2 (2 years) and the last thirty days pay stubs
Last 2 years tax returns
Bank statement, last few months - all accounts
Certificate of Eligibility (VA)
Divorce decree/seperation agreement if applicable
Other papers may be required depending on the loan