Objectives This study provides regression and classical calibration models for the estimation of age from the dimensions of the metaphyses and epiphyses of the six long bones. Methods A sample of 148 known sex and age individuals (56 females and 92 males), aged between birth and 12 years of age, selected from Portuguese and English skeletal collections. Age estimation models were obtained separately for each sex and for the sexes combined, for the entire sample and for the sample divided into two subsamples at the age of 2 years. Results The best performing epiphysis is the proximal epiphysis of the tibia. For the metaphyses, the distal metaphysis of the tibia and the proximal metaphysis of the femur are best for individuals below and above 2 years of age, respectively. Growth of the metaphyses is similar to that of the diaphysis. Results suggest that age can be as accurately estimated from the width of the metaphyses and epiphyses as from the length of the diaphyses, or as from the length of the deciduous and permanent teeth. Conclusions These models may be useful for fragmentary material in both archaeological and forensic contexts. However, due to the background of the samples, the models would be most applicable to individuals exposed to adverse environmental conditions during growth and development. Metaphyseal and epiphyseal widths may be less affected by ecological conditions than diaphyseal length.