Manufacturing contributes heavily to environmental life cycle measures such as energy, material use, and water consumption through depletion and pollution. To lessen the environmental impacts, a number of initiatives have been developed. One of such initiatives is the used product take back, a process through which manufacturers collect used products and remanufacture them to like-new condition. However, remanufacturing of the used products at a modest cost is becoming a daunting task for many manufacturers due to the increasing complexity in many products. To mitigate this remanufacturing challenge, this paper develops a metric to quantify the remanufacturability incorporated into the new product at the design stage. The metric is based on entropy, a phenomenon well known in engineering.