Chronological Age Calculator
Calculate exact age in years, months, and days for neuropsychological test norming. Supports premature birth adjustment.
Why Exact Age Matters
Neuropsychological test norms are organized in narrow age bands — often as small as 1-month intervals for young children. A child who is 6 years, 0 months performs in a different normative group than one who is 6 years, 3 months. Using an approximate age can shift a score by 5–10 standard score points.
Best practice: Always calculate age to the day and verify the correct normative table in the test manual before scoring.
Premature Birth Adjustment
For children born before 37 weeks gestation, corrected (adjusted) age should be used for developmental assessments until approximately 24–36 months of age (depending on the test manual's guidance). The correction subtracts the number of weeks premature from the chronological age.
Enable the "Adjust for premature birth" checkbox above and enter the gestational age at birth to see both chronological and corrected ages.