Wal-Mart Stores Inc shoppers can now research the trove of product data the world's largest retailer gathers, through a new iPad app and updated app for Apple Inc's iPhone.

The move comes as Walmart tries to win over customers who are doing more research and shopping on their gadgets.

Three-quarters to 92 percent of shoppers at Walmart U.S. stores bring in lists when they shop, Gibu Thomas, Walmart's senior vice president of mobile and digital, said in an interview.

Through the apps, Walmart will share data with the 140 million shoppers who head to its U.S. stores each week, showing them which items are in stock, which ones are available online and whether there are manufacturer coupons valid for their purchases.

It's the same kinds of things now, that we used to do for our suppliers and for our own store associates, now we're doing for our customers, said Thomas, who as a self-described geek in Silicon Valley owns an iPad 2 and an iPhone.

Over half of shoppers that have both a computer and a tablet at home prefer to shop on their tablets, he said.

Walmart, the retailer's largest division, has had an iPhone app since last fall and just launched its iPad app last week, Thomas said.

As of late Tuesday, the iPad app in Apple's app store had 20 ratings with an average score of 4-1/2 stars. That matches the rating of rival Target Corp's iPad app, which was launched nearly a year ago and has more than 170 user ratings.

Once Apple approves Walmart's updated iPhone app, shoppers will be able to create shopping lists on their iPhones. Those who shop at a small number of stores will also see exactly which aisle they should head to in their local Walmart to find the goods on their lists.

The new shopping list function for iPhones also tallies the total price each time shoppers add items to their lists, helping them budget their planned purchases.

Those who have the latest iPhone 4S can even speak their shopping lists into their phones.

Some of the technology is still in the works. For now, shoppers can see coupons online but must print them out to redeem them at Walmart stores. Redeeming coupons directly from the phone could come in the future, Thomas said.

Other retailers, such as Safeway Inc, allow shoppers to select coupons and have them automatically applied to their purchases when they use their loyalty card or enter their phone number at the checkout. Walmart does not have a loyalty program.

Based on 2010 data, roughly one-third of Walmart's customers had a smartphone, which was in line with the general population at the time. Nielsen expects 50 percent of mobile phone users to have smartphones by the end of the year.

Walmart has not tracked how many of its shoppers have iPads.

Walmart also has an app for Google Inc's Android platform and a mobile website viewable from devices such as Research In Motion Ltd's BlackBerry smartphones.

(Reporting by Jessica Wohl in Chicago; Editing by Richard Chang)

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