Normal hemoglobin values are related to the person's age and sex. Normal values may vary slightly between test systems, and which groups of doctors have determined normal values for their group of patients; however, the value ranges are close (vary by about 0.5 g/dl) for almost every group. Age 2 to 6 years: 11.5 to 13.5 g/dl (mean 12.5 g/dl). 2  Age 6-12 years: 11.5 to 15.5 g/dl (mean 13.5). 3  Female. 4  Age 12-18 years: 12.0 to 16.0 g/dl (mean 14.0 g/dl).