Volume of some agricultural and food materials, i.e. cantaloupe, kiwifruit and egg were measured using water displacement and image processing methods. The volume determined from image processing method (IPM) was compared to the volume determined by the water displacement method (WDM) using the paired samples t-test and the Bland-Altman approach. The paired samples t-test results showed that the volume determined by image processing method was not significantly different from the volume measured by water displacement method. The Bland-Altman approach also indicated that image processing method satisfactorily estimated volume of the selected agricultural and food materials. Accordingly, image processing provides an accurate, simple, rapid and non-invasive method to estimate volume of agricultural and food materials and can be easily implemented in sorting of agricultural and food materials.