Potential homebuyers routinely misjudge how much of a down payment they'll need to buy a home, often assumed they'd need 3-5 times more than is actually required.

A recent survey of renters and adults living in someone else's found that two out of five said they believed lenders would require a minimum of 15 percent down for a mortgage. In reality, FHA mortgages allow down payments of as little as 3 percent, while borrowers with good credit can get conforming mortgages backed by Fannie Mae or Freddie Mac with as little as 5 percent down.

On average, the non-homeowners responding to the survey said they believed lenders would require a down payment of 11-15 percent. The survey was conducted by the New York analytical firm Zellman and Associates.

The survey found that only 28 percent of all survey respondents thought they could qualify for a mortgage, although that figure rose to 40 percent among the prime first homebuyer demographic of 30-34 year-olds.

Just over one in five borrowers who took out a conforming mortgage (backed by Fannie Mae or Freddie Mac) so far this year have put down 10 percent or less, according to Freddie Mac executive Christina Boyle.

Financial assistance options

In discussing the survey results, Boyle noted that borrowers may be able to obtain assistance in putting together the money for a down payment, such as through gifts from family members or by obtaining a grant or loan from a non-profit agency or public institution.

Boyle noted in particular the HOME Investor Partnerships Program and the American Dream Downpayment Initiative, two federal initiatives providing down payment and other financial assistance to aspiring homeowners. Both are state-based initiatives funded through the Department of Housing and Urban Development (HUD).