Chewing efficiency is the ability to grind some food in the given time. Evaluation of chewing efficiency is important in assessing the success of dental treatment or detecting the masticatory function problem that could be arising from some systemic diseases. The smartphone is an available device that everyone carries at all times. Using a smartphone as part of the chewing efficiency analysis will simplify the method and facilitate clinical diagnosis. Therefore, this study aimed to determine the reliability of the two-color chewing gum test, in which digital images were taken by a smartphone and analyzed by the ViewGum software for chewing efficiency. Twenty-one participants with normal chewing function were assessed by chewing a two-color chewing gum for 20 seconds, and the chewing ability is evaluated by the mixing of colors. The digital images of chewing gum specimens were captured by a scanner or a smartphone to be analyzed for the variance of hue (VOH) using the ViewGum software. The degree of incomplete mixing chewing gum presents with a range of VOH. Pearson correlation showed a highly positive correlation between the VOH obtained from scanned and smartphone images (r=0.749, P<0.01). The Intraclass Correlation Coefficient (ICC) was 0.75 considered good reliability (p<0.001; 95% CI 0.477-0.890). This study suggested that both scanned and smartphone digital images are equally valid for the analysis by the ViewGum software to determine chewing efficiency. Using a smartphone to capture digital images will simplify the method and increase clinical use.