The definition of a “Jumbo Mortgage” is a mortgage loan whose total amount is higher than the standard conventional limits. Jumbo loans are simply mortgages for higher-than-normal loan amounts. The gold standard of “normal” in the lending industry is what is called a “conforming, conventional” loan; that is, a loan that conforms to the secondary market agencies' conventional underwriting requirements regarding credit, income/asset verification, property features, etc.

As of February 20th, 2007, the maximum amount for this “conforming” loan is $417,000 for a single unit property, $533,850 for a 2-unit property, $645,300 for a 3-unit property and $801,950 for a 4-unit property. The conventional limit for second loans is $208,500 and all loan limits are 50% higher for properties in Alaska, Hawaii, Guam, and the U.S. Virgin Islands. These limits change periodically with the real estate market.

Most lenders are willing to lend over and above these conforming amounts, but the larger jumbo loan amount translates into a larger risk for the lender should you default on the loan. Simply stated, the more the bank lends, the more it stands to lose if something goes wrong and they need to foreclose on that property.

Because the lender is taking an increase in risk with the size of the loan, they will typically charge a higher interest rate than they would on a loan that is within the “conventional” loan limits. All lenders vary in the premium they add for jumbo loans, but a good rule of thumb is to expect to pay an interest rate about 0.5% higher than you would for an otherwise identical conforming loan.

With conventional lenders, these jumbo loan amounts are set in stone, particularly if they are backed by Fannie Mae or Freddie Mac. In other words, a mortgage for $417,000 from one lender at 6% will almost always be about 6.5% for a loan of $417,001 from the same lender.