Starbucks says more than 10 per cent of in-store transactions in the US are done via mobile phones.

The figure was disclosed at Starbucks’ quarterly earnings call (along with news that the coffee chain had surpassed the four million follower mark on Twitter).

Starbucks says it is also installing wireless charging mats in more stores as part of its digital drive.

“This is the kind of improvement to the digital experience that our customers expect,” said Adam Brotman, Starbucks’ chief digital officer. “Our internal measures tell us that these various digital initiatives have added demonstrable impact to our US business in the third quarter, with the promise of even greater growth in the months and years to come.”

Helping Starbucks drive mobile payments is its acceptance of multiple platforms. Aside from Starbucks’ own mobile app, Apple’s Passbook and Square Wallet are among those accepted by the coffee chain.