The average rent in some central Auckland suburbs is dropping - as more small homes go on the market.

A New Zealand Herald analysis of rental bonds data has found prices are dropping in a string of central suburbs forming a near-halo around the CBD.

Real estate data analyst Leon Hong says property types are changing.

According to him, they're getting a lot smaller.

He says that means more apartments, terraced housing, and rooms listed separately on Airbnb.

"The supply has been increased," he says.

"Especially in central suburbs like Epsom and Newmarket and Ponsonby et cetera."