• by Erik Sass  @eriksass1, March 3, 2009

Magazine Web sites attracted an average 75 million unique visitors per month in the last three months of 2008, compared to a monthly average of 67.5 million during the same period of 2007--an increase of 11%, according to the Magazine Publishers of America, citing its analysis of Nielsen Online data for 476 magazines online, from The Economist to Better Homes and Gardens.

The growth rate for magazines' Web audience far exceeds the 3.2% growth rate for the Internet overall. Seventy-five million unique visitors in the fourth quarter of 2008 equals 45.1% of the total Internet-using population of the United States, compared to 41.8% during the same period in 2007.

What's more, the duration of visits is also increasing.

Visitors spent an average 2.4 billion minutes per month perusing magazine Web sites, an increase of 34.4% over 1.78 billion minutes in 2007. Doing the math, the average time spent per visitor rose from about 26.4 minutes per month in the fourth quarter of 2007 to 32 minutes per month in the fourth quarter of 2008. The MPA didn't release any figures for page views.

However, the good news on unique visitors and time spent highlights a major problem faced by magazine publishers: While their online audience is booming, online advertising revenues still trail far behind. Like newspaper publishers, magazines have struggled to monetize their online readership, and online advertising, in most cases, is still a small fraction of their overall business.

At Time Inc., online revenues were just 10% of total advertising revenues of $2.45 billion in 2008. At Martha Stewart Living Omnimedia, they were about 12% of about $90 million in total ad revenue. At Meredith Corp., online contributed about 6% of total revenues for the company's fiscal year 2008.

These figures are critical because--again, like newspaper publishers--most big magazine publishers are not coming close to making up losses in print ad revenue on the online side. At Time Inc., for example, total revenues declined $347 million from 2007-2008, dwarfing total online revenues of $245 million.