This year 26 million U.S. adults are using tablet computers; next year the number will increase to 50.7 million and hit 82.1 million by 2015, Forrester Research Inc. predicts. And of the 24.1 new tablets sold this year, at least 20 million will be iPads, the research firm says.

Apple Inc.’s iPad is changing the way consumers interact with the Internet—and as a result, changing the way consumers interact with e-commerce sites. Owners of iPads are a force to be reckoned with, and so far, the top e-retailers come up short when it comes to meeting the needs of the tablet shopper, according to a new study by Alexander Interactive.

The e-commerce and m-commerce design firm examined the performance on iPads of the e-commerce sites of the top 10 e-retailers in the Internet Retailer Top 500 Guide. It based its judgments on numerous criteria, including responsive design, adaptive layout, appropriate content sizing, minimal clutter, finger-swipe support, web standards compliance (including not using Adobe Flash, which does not work on iPads), tap-only navigation displays, tablet-optimized search and tablet-optimized purchasing.

“None of the sites surveyed offered dedicated tablet experiences, though most offered dedicated iPad or iPhone apps,” Alexander Interactive writes in its report. “All suffered from usability problems, and offer limited tablet shopping experiences in comparison to those offered by companies with dedicated tablet site experiences, such as Nike. Retailers should seriously evaluate investment in t-commerce site design due to the forecasted explosion of tablet usage in the next several years.”

Of the top 10 e-retailers studied, Amazon.com Inc.’s site was the most usable on a tablet, the study finds. Amazon recently redesigned its site with tablet computers top of mind. The merchant redesigned the site to be simpler and less cluttered, with larger buttons that are easy for tablet users to tap compared with standard links or smaller buttons, Alexander Interactive says. The biggest improvement is a fly-out window that swoops out when a user touches Shop By Department; the menu’s bold text reads well on both PC monitors and tablets and the category links function correctly when tapped, which can’t be said for all of the top 10 e-retailers, the design firm says.

Staples Inc.’s e-commerce site was more typical of sites in the study: a reasonably good desktop experience that functions reasonably well on an iPad, Alexander Interactive says. Drop-down menus, though, are a bit cluttered, and everything on standard pages is a bit too small for the smaller screen of a tablet, the firm contends.

Predictive or type-ahead site search works well on Apple’s e-commerce site rendered on an iPad; this is important as it saves tablet users time typing on the onscreen keyboard, Alexander Interactive says. Apple, iPad’s maker, is a leader in design with tablets in mind, offering uncluttered pages; but it could do even better with a dedicated tablet site, the firm argues.

And Walmart.com enables customers on iPads to fairly easily use its e-commerce site, especially when an iPad user holds the device horizontally in landscape mode; in some areas the retailer has added extra space between links to better accommodate finger tapping, Alexander Interactive says. However, many of the site’s promotional areas use Adobe Flash, which leaves shoppers watching the message “Loading” on the screen, the firm adds.

Alexander Interactive points to the dedicated, tablet-optimized e-commerce site of Nike Inc., No. 78 in the Internet Retailer Top 500 Guide, as an exceptional example of what merchants need to do to be prepared for the onslaught of tablet shoppers.

“Browsing to Nike.com reveals a beautiful and engaging web site built for the iPad,” the firm says. “The site features high-resolution photography and a tap-friendly user interface. Sliding your finger across the list of products at the bottom of the screen reveals additional options. Product listing pages adapt to the orientation of the tablet, showing different numbers of products depending on available screen real estate. It’s a quick, easy way to find what you’re looking for.”

Favorite