Background Age estimation of a minor whose identity is unknown must be accurate enough to respond to judicial requests. The main objective of this study is to accurately determine a teenager's age from simple and reproducible criteria. Samples and Methods The first reference sample consists of 1720 measurements collected from 170 teenagers aged 11 to 16 years, over a period of 5 years. A second validation sample of 735 teenage boys aged 11 to 16 made it possible to verify the relevance of our estimates. The degree of maturation was determined using 4 pubertal stages: the stage below the age of puberty, the prepubescent stage, the parapubescent stage, and the pubescent stage. For each pubertal stage, an optimization of the values of the age was carried out in order to reduce the differences between the estimated and the actual age at the different age groups. Results The mean differences between estimated age and actual age from these values were -0.06 +/- 0.91 years for the reference group and -0.49 +/- 0.73 years for validation group. Conclusions Our method of age estimation is simpler and accurate. It could be used routinely in a forensic frame to respond to judicial requests.