Chronological Age Calculator
Exact age as of a test date — in years, months, days, and the years:months notation used on assessments.
Fill in the fields above to see your result instantly.
Chronological age is a person's exact age on the day of a test or assessment, expressed in years, months, and days. Psychologists, speech-language pathologists, and teachers need it to score standardized instruments such as the WISC, WPPSI, and developmental scales, where the correct norm table is chosen by age. Enter the date of birth and the assessment date and this calculator returns the exact age, the years:months notation used on report forms, the age in whole months, and decimal years — calculated in your browser, never stored.
How to use the Chronological Age Calculator
- 1
Enter the date of birth
Use the testee's date of birth.
- 2
Enter the assessment date
Set the day the test is administered. It defaults to today.
- 3
Read the chronological age
Use the years:months value for the norm table, or the exact years-months-days breakdown for records.
Examples
Frequently asked questions
What is chronological age?
Chronological age is the precise amount of time a person has been alive as of a given date — usually expressed in years and months for assessment scoring, for example 8 years 4 months (written 8:4).
How is chronological age used in testing?
Standardized tests like the WISC-V or WPPSI select the comparison (norm) group by the testee's chronological age at the time of testing, so an accurate age is essential for correct standard scores.
Should I round the months?
Many test manuals round chronological age to the nearest whole month and explicitly tell you not to round days up to a month. This tool shows both the exact days and the nearest-month figure so you can follow your manual's rule.
What is decimal age?
Decimal age expresses the age as a single number of years (for example 8.42), which some growth charts and research instruments use instead of years and months.
Does this replace my test manual's instructions?
No. It computes the age accurately, but always follow your specific instrument's scoring rules for how age is recorded and rounded.