The most common type of mortgage loan which specified a fixed interest rate and a constant monthly payment, generally for 15 or 30 years. Financial institutions typically lend a maximum of 75% to 80% of a home's appraised value on a conventional loan, meaning that you must come up with a down payment for the remaining 20% to 25%. A smaller down payment is acceptable when a borrower chooses to purchase insurance that guarantees the lender against loss.