We have created the tool BioAlder as an age prediction model based on the systems Greulich and Pyle (hand) and the Demirjian's grading of the third molar tooth. The model compiles information from studies representing a total of 17,151 individuals from several parts of the world. The model offers a solution where issues as group-wise data format and age mimicry bias are bypassed. The model also provides a solution for combining the two grading systems, hand and tooth, to one combined age prediction result assuming independency. We have tested our model of age prediction and the independency assumption on a separate data set from Lebanon with 254 young individuals. The prediction intervals of BioAlder covered most of the data points; however, we observed some outliers. Our analyses indicate at least a weak dependency between the two methods.