Systems, methods and tools for tracking the amounts of merchandise being displayed or available for sale in a retail environment using measurements of air displacement caused by the movement of customers, employees and shopping carts throughout a retail environment. The disclosed embodiments may position air displacement sensors throughout a store and near the products being offered for sale. As the merchandise is removed by customers, a greater amount of air may be measured. Embodiments of each sensor device may be calibrated with a maximum threshold measurement of air displacement corresponding to the amount of merchandise surrounding the sensor. After enough of the products have been removed from the surrounding proximity of the sensor, the maximum threshold of air displacement may be reached, wherein upon exceeding the maximum threshold of air displacement a signal may be sent alerting employees to restock the specified merchandise proximate to the sensor's location.