US online advertising spending, which grew 23% to $32.03bn in 2011, is forecast to grow further by 23.3% to $39.5bn in 2012, ahead of total ad spend on print newspapers and magazines, according to a study by eMarketer.

Print advertising spending is expected to decline from $36 billion in 2011 to $33.8 billion in 2012, the research firm forecasts.

eMarketer’s previous forecast from July 2011 for US online advertising was among the more optimistic estimates to have come out during the year.

eMarketer principal analyst David Hallerman said advertisers’ comfort level with integrated marketing is greater than ever, and this is helping more advertisers — and more large brands — put a greater share of dollars online.

The increasing amount of time users spend on digital mediums and also the advertisers’ view of the internet, which is perceived to be more measurable than other medium, are the drivers behind the growth of the online advertising, eMarketer said.