Opto Grape Caliper (OGC) is an optical, non-invasive instrument for measuring the dimensions of table grapes. It was designed for producers' production lines who need an easy-to-use yet accurate instrument that tells the size of the grapes while they remain in the cluster, for classification purposes. A currently manual process using calibrated rings, OGC uses a proprietary optical design to acquire an image of the cluster to identify the individual grapes, to then measures the size of each of them, with an accuracy of 0.1 mm. Using industry classification, OGC totalizes grapes and shows them in numeric displays. It is possible to take several images of different angles of the cluster, to get a total of grapes per category.