Millions of Americans say they want to buy a home this year, but many won't be able to, according to a new survey from online real estate firm Zillow Inc., CNNMoney reported.

The reasons: Limited supply of homes, soaring prices and strict lending standards. In all but one of 20 metro areas Zillow surveyed, 5 percent or more of residents said they wanted to buy a home in the next 12 months.

The desire to buy a house is particularly strong for renters; 10 percent of them want to buy. That would translate into 4.2 million first-time buyers, double the number who purchased in 2013.

Renters in Miami, Atlanta and Las Vegas expressed the most desire to become homeowners, according to Zillow's index. Prices in the South Florida metro area are still about 40 percent off their highs, and the median price of homes sold lately is well under $180,000, much more affordable than in other major cities.