Rule of Thumb: You can AFFORD a house NOT more than 2.5 times annual income, stretched to 3 times at Most.Rule of Thumb: Not more than 1/4 of monthly income for mortgage payment (PITI), not more than 1/3 with utilities added in.Putting 20% down is GREAT, it avoids extra cost of PMI and means you have some equity in your new home. You have positioned yourself well to buy with low debt and good savings for down payment. However, some lenders require 2 year job history, along with good credit rating, adequate income (see rule of thumb), sufficient down payment. Standard mortgages are 25-30 year. Locks on interest rates are good for finite period of time, generally 30-90 days ONLY. Longer your amortization, the MORE you're paying in interest.