In this article we aim toward to assessing how accurate and valid the measurement estimates made by smartphone apps programs are on photos taken by smartphone digital camera when compared to those obtained from plaster models. A set of several alginate impressions was taken from siblings with different types of occlusion. Each impression was made into a plaster cast and photos were taken by smartphone digital camera. Direct photos were also taken of siblings’ dentition. Different mobile apps software programs that are currently available for both Iphone and Android OS smartphones were then used to measure the photos of the tooth widths at their greatest mesiodistal dimension and arch length. Tooth and arch widths were again physically measured on the plaster models with a divider and a millimeter ruler. When comparing measurements estimated from the smartphone photos, obtained through different measuring smartphone apps, with those of the conventional plaster dental study models, we found that there was no significant difference in space analysis between them.