Work out exact chronological age at any assessment date — years;months;days, the format used in speech, education and psychological testing.
Why chronological age has its own calculator
Speech-language pathologists, school psychologists and paediatric assessors need a child’s age on the test date, written as years;months;days — because standardised test norms are looked up by exactly that. The arithmetic uses calendar borrowing (days from the previous month’s actual length, then months from years), which is easy to slip on by hand at the end of a testing session. This calculator does the borrowing and shows the age in every format the paperwork asks for.
How to use it
- Enter the date of birth.
- Enter the test or assessment date (it defaults to today).
- Read the age as Y;MM;DD, in total months, and in total days.
The method
A worked example
A child born 24 March 2017, assessed on 13 August 2026, is 9;04;21 — 9 years, 4 months, 21 days — which is 112 months or 3,430 days. Norm tables keyed by “9;0–9;5” pick up the 9;04 immediately, with no manual borrowing at the desk.