Apple is way in front when it comes to sales per square foot. Retail and consumer goods consulting firm RetailSails says Apple's 372 worldwide locations sold goods at a rate of more than $6,000 per square foot of floor space in the past 12 months. The average store of the next most successful company in the United States, Tiffany & Co., sold less than half that per square foot. Sales per square foot in lower end stores were less than $100.