Abstract Length, width, and thickness of tall fescue (Festuca arundinacea), orchardgrass (Dactylis glomerata), and perennial ryegrass seeds (Lolium perenne) were measured by a machine vision system and by four human operators using a microscope with a reticle. Statistical analysis showed that the consistency of machine vision measure-ments was greater than that of the human measurements and required about one-third of the time. Overall accuracy of machine vision system measurements appears to be sufficient to be the basis for selection of screen opening and indent pocket sizes used in seed conditioning operations.