Abstract: An inventory sensor for monitoring the inventory status at one or more retail shelves. The inventory sensor may comprise a mat and a plurality of opposing contact pairs. The mat is adapted to be disposed on a retail shelf with a forward edge of the mat facing the front of the retail shelf. The plurality of opposing contact pairs are arranged into a plurality of regions within the mat, the regions being arranged forward to aft in the mat with the first region being disposed along the forward edge of the mat and subsequent regions being disposed sequentially further aft from said first region. The contact pairs are biased open and the closing of an opposing contact pair produces results in the production of an electrical signal associated with the closed opposing contact pair. A controller monitors the mat to determine retail item footprints.