That means warehouse design can eventually be modified to have more shelf space and less wide aisles. At the end of the third quarter of 2015, Amazon was using 30,000 Kiva robots across 13 warehouses. Each Kiva-equipped warehouse can hold 50% more inventory per square foot than centers without robots. In turn, the company’s operating costs have been sliced by 20%—or almost $22 million—per warehouse.