That’s according to data from Bizrate Insights, a division of Connexity, which polls online shoppers about their experiences across thousands of online retailers.

In the first quarter of 2014 well over half of mobile purchases were made using a tablet device. By the first quarter of this year, that number had dropped to 36%, the same percentage as iPhones.

Android smartphones were seen to account for 28% of mobile online purchases.

Despite the fact that most online purchases are still taking place on the desktop and a quarter of shoppers don’t use a mobile device at all, mobile devices are increasingly impacting how consumers behave in-store.

According to Bizrate Insights, 21% of shoppers use their mobile devices in-store, and two-thirds of this segment of shoppers use those devices to comparison shop and locate coupons.

The majority (63%) of all consumers say they check stock using a mobile device before they visit a store, or believe doing so is a good idea.

The smartphone challenge

While most retailers are no doubt aware that more and more of their traffic is coming from mobile devices, and that mobile is affecting how consumers shop offline, Bizrate Insights’ data highlights the importance of smartphones specifically.

Building great mobile shopping experiences can be difficult, and tablet and smartphone users have high expectations.

But there are many differences between meeting those expectations on tablet versus smartphone devices. Tablets typically have more screen real estate than smartphones, and in many cases more capable hardware.

Tablets are also frequently used in home environments with WiFi whereas smartphone shoppers may be on mobile networks that don’t offer the best connectivity.

Smartphones are also more likely than tablets to be used in-store, so retailers looking to address showrooming and better serve their mobile-savvy customers have good reason to ensure that their mobile offerings are up to par.