A new consumer survey by Deloitte sheds light on just how fast smartphones are impacting the retail scene.

By 2016, smartphones will influence $689 billion or 19 percent of total U.S. store sales, according to results of the survey. Direct mobile commerce sales will surpass $30 billion by then, according to industry estimates.

This year, 5.1 percent of total retail sales, or $159 billion in sales, will be influenced by mobile devices, which enable consumers to conduct product research, compare prices and purchase online. Direct mobile commerce sales are estimated at $12 billion for 2012.

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“Mobile devices’ influence on retail store sales has passed the rate at which consumers purchase through their devices today,” said Alison Paul, vice chairman of Deloitte LLP and the research firm’s retail and distribution sector leader.

“Consumers’ store-related mobile activities are contributing to — not taking away from — in-store sales, and our research indicates that smart phone shoppers are 14 percent more likely to convert and make a purchase in the store than non-smartphone users. This means that mobile is an important tool for retailers to incrementally drive traditional in-store sales, strengthening the relationship between retailer and consumer.”

“Retailers that do not engage shoppers through specialized mobile applications or targeted smartphone-based promotions leave the door open for competitors to reach a customer who is standing in the retailer’s store and at the point of purchase,” added Kasey Lobaugh, principal and direct-to-consumer and multichannel leader, Deloitte Consulting LLP. “To make the connection with consumers, retailers need to understand how mobile shoppers are willing to interact with their specific store category, format and merchandise, both inside and outside the store, and customize their mobile strategy around the shopper’s needs and experience.”

Deloitte’s survey was conducted online by an independent research company from March 20 to March 30, 2012. The survey polled a national sample of 1,041 random consumers and then augmented this sample with additional smartphone owners to reach a sample of 1,557 smartphone owners.

Forty-eight percent said their smartphones have influenced their decision to purchase an item in a store, and the usage is highest at or near the point of purchase. Sixty-one percent said they use their devices to shop at the store, and 52 percent reach for their phones on the way to the store.

Deloitte said that “smartphone-toting consumers appear more likely to make a purchase than those who do not own one or do not use it to assist in-store shopping.” When asked about their most recent shopping trip, 72 percent of smartphone owners indicated they made a purchase on that day, compared with 63 percent who did not use a phone.

According to the Deloitte findings:

• Smartphone users are more likely to eventually make a purchase.

• 37 percent of smartphone owners who used a smartphone on their last shopping trip utilized a third-party mobile shopping application; 34 percent used a retailer’s mobile application.

• Consumers are quick to tap their devices for shopping assistance, with smartphone use for store-related shopping increasing 40 percent after the first six months of ownership.

• The mobile factor is strongest among younger shoppers, with 67 percent of smartphone owners between 14 and 34 using their devices to shop, and 55 percent indicating smartphones have influenced their decision to make a purchase.