Chronological Age Calculator

Enter a birth date and (optionally) a reference date. The calculator returns years, months and days.

How to use the chronological age calculator, Pearson

Here’s a simple, clear explanation of how to use a Chronological Age Calculator (Pearson-style) — the same kind used in educational or psychological testing (like the WISC, WAIS, or CELF assessments).

What It Does

A chronological age calculator finds a person’s exact age — in years, months, and days — at the time of testing or assessment.
It’s often used by psychologists, therapists, or teachers to score standardised tests accurately.

How to Use It (Step by Step)

1. Open the calculator
   • If you have the HTML version (like the one I gave you), open the .html file in your web browser.
2. Enter the Birth Date
   • Type or pick the date of birth of the person being assessed.
     Example: 2012-08-15
3. Enter the Test or Reference Date
   • This is the date of assessment (or any date you want to measure the age at).
     Example: 2025-10-06
     (You can leave it blank to use today’s date.)
4. Click “Calculate Age”
   • The calculator will instantly show something like:
     13 years, 1 month, 21 days
5. Read the Breakdown
   • You’ll also see:
     • Years
     • Months
     • Days
     • Total days and months (optional)
6. Optional Tools
   • Clear: Resets the form.
   • Copy Result: Copies the result (useful for reports or records).

Example

So, if a student was born on August 15, 2012, and tested on October 6, 2025, their chronological age is 13 years, 1 month, and 21 days.