• by Gavin O'Malley  @mp_gavin, September 5, 2013

No longer a niche play, mobile ecommerce will play an important role in overall digital holiday spending this season. That's according to a new forecast from eMarketer, which says mcommerce is growing faster than most analysts expected.

Overall, U.S. retail ecommerce sales for the holiday season (from November through December) are expected to reach $61.8 billion -- up from $53.7 billion year-over-year.

If accurate, that will equal roughly 15% in year-over-year growth -- about the growth rate witnessed from 2011 through 2012.

This year, however, eMarketer expects that mobile’s share of all holiday ecommerce will reach 16% -- up from the firm’s previous prediction of a 15% share. “The revision comes as data sets from multiple research sources showed mcommerce as a percent of retail ecommerce sales reached record highs earlier this year,” eMarketer said in a statement.

“In addition, large retailers, such as Best Buy and Home Depot, continue to invest heavily in smartphones and tablets, building out their mobile app and website offerings, and increasing spending on digital advertising in an effort to drive more conversions across devices and compete with companies with strong mobile infrastructure like Amazon and eBay.”

In total, eMarketer predicts retail mcommerce sales will reach $41.68 billion this year -- and by 2017, mobile-based retail sales will surpass $100 billion.

Mobile devices contribute to overall commerce sales growth in two ways -- both as a driver of total sales, and increasingly, as a shopping research tool -- according to eMarketer. Now and for the foreseeable future, tablets are exceptionally important for mcommerce sales growth, eMarketer believes.

This year, eMarketer predicts, tablet retail mcommerce sales will hit $26.05 billion, or 62.5% of U.S. retail mcommerce sales overall -- up from last year when tablets took a 56.2% share of mcommerce retail sales. That will leave smartphones with a 35% share of mcommerce sales -- a percentage that will continue to shrink throughout the forecast period as sales on tablets maintain far higher growth rates.

By 2017, smartphones will account for 27% of retail mcommerce sales, eMarketer predicts. Yet actual sales dollars spent on purchases made via smartphones will continue growing at healthy double-digit rates.

This year, retail sales made on smartphones will total $14.59 billion -- and that figure will more than double to $30.66 billion by 2017. For the entirety of 2013, total U.S. retail ecommerce sales are expected to reach $262.3 billion -- growing by 16.4% during the year.