Watermelon is the largest fruit in volume and mass; these characters cause many problems in transportation and handling of watermelon. This research performed to determine and compare physical and mechanical properties in different sizes and varieties of watermelon in order to obtain parameters used in transportation, handling, harvesting, and storage. A statistical factorial method in the form of completely randomize design (2× 3) was used to determine the physical properties of watermelon such as mass, volume, dimensions, density, spherical coefficient and geometric mean diameters. Another statistical method in the form completely randomize design (2× 3×4) was used to determine mechanical properties of watermelon such as stress, strain, elasticity modulus and toughness. The experiments data were analyzed by SPSS V.9 software. It is found that increasing watermelon sizes tends to decrease spherical coefficient and density. The smallest size of Charleston gray had maximum density (0.96 gr/cm3) while the largest size of Crimson sweet had minimum density (0.93 gr/cm3) in the treatments. Comparing mechanical properties in two varieties of watermelons showed that mechanical properties of watermelons are significantly affected by size and variety.

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