Rice grain number and grain dimensions including grain length-width ratio are critical components in determining the rice yield and quality. Manual or visual inspection for breeding lines and germplasm over these traits are time-consuming jobs. We developed and tested two algorithms for analysing grain number and dimensions (grain length, grain width) through image analysis system, Metamorph offline 7.0 (Molecular devices™). The algorithm for determining number of grain and shape constitutes a series of fragmentation processes including Shading, Color separate, Threshold, Euclidean, Dialate, Watershed Line, Arithmetic. When the six rice cultivars with different grain shapes were tested, there was no difference in the averaged values and distribution for the grain number and grain length between mannual and image analysis methods. However, image analysis resulted in the slightly increased values for grain width and more wider distribution whereas length/width ratio was slightly reduced by about 0.1, indicating that image analysis can be utilized more effectively and accuately in investigating the grain number and dimensions for sizable breeding lines.