Mortgage term. Mortgages are generally available at 15-, 20-, or 30-year terms. The longer the term, the lower the monthly payment if the same amount is borrowed. However, you pay more interest overall if you borrow for a longer term.. A fixed rate allows you to lock in a low rate for as long as you hold the mortgage and is usually a good choice if interest rates are low. An adjustable-rate mortgage (ARM) is designed so that interest rates will rise as interest rates increase; however they usually offer a lower rate in (0 comments)