Cantaloupe (Cucumis melo) volume was measured using water displacement and image processing methods. The volume determined from image processing method was compared to the volume determined by the water displacement method 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 (P> 0.05) different from the volume measured through water displacement method. The mean and standard deviation of the volume difference between the two methods were -81.1 cm3 and 237.4 cm3, respectively (95% confidence interval: -212.5 and 50.4 cm3, P= 0.207). The average percentage difference between the two methods was 7.60%. The Bland-Altman approach was also indicated to be a satisfactory, image processing method suitable for volume estimation of almost all size cantaloupes. Accordingly, image processing provides an accurate, simple, rapid and non-invasive method to estimate fruit volume and can be easily implemented in monitoring fruit growth as well as in sorting of fruits during postharvest processing.