Reviewed by Xixuan Wang, Psychological Counselor · Last reviewed
This speech therapy age calculator gives a child's exact age on the assessment date in years, months and days, plus the years;months figure — the number SLPs need before selecting a norms table.
For everyday age calculations, use our chronological age calculator.
Chronological age on the assessment date
Verify before you score. This is a calendar calculation, not a scoring tool. Publishers set their own borrowing, rounding and age-band rules, so confirm the result against the official test manual before choosing a norms table. This site is independent and is not affiliated with or endorsed by any assessment publisher.
A speech therapy age calculator answers one narrow question: exactly how old was this child on the day you administered the test? Standardized speech and language assessments are normed in narrow age bands — often three or six months wide — so a single miscounted month can move a child into the wrong norms table and change every standard score that follows.
The formula every SLP uses is the same:
Chronological Age = Assessment Date − Date of Birth
Worked by hand, you write the assessment date above the date of birth in year / month / day columns and subtract right to left, borrowing 30 days from the month column and 12 months from the year column when a column goes negative.
A child born on 14 March 2019 is assessed on 28 October 2024.
| Step | Year | Month | Day |
|---|---|---|---|
| Assessment date | 2024 | 10 | 28 |
| Date of birth | 2019 | 3 | 14 |
| Difference | 5 | 7 | 14 |
The child's chronological age is 5 years, 7 months, 14 days, written 5;7 in most report templates. No borrowing was needed here because both the month and the day columns subtracted cleanly — the calculator above handles the borrowing automatically when they do not.
Everyday age — "she's five" — is not precise enough for a speech-language evaluation. Exact chronological age drives several decisions in a single evaluation:
Because the figure is reused so many times inside one report, it is worth calculating once, carefully, and copying it forward — which is what the calculator at the top of this page is designed for.
Speech-language and educational reports write chronological age with a semicolon: 4;11 means four years and eleven completed months. The semicolon matters — 4.11 in decimal notation would mean roughly four years and one-and-a-third months, which is a very different child. The calculator above reports both the semicolon notation and the decimal age so you can copy whichever your paperwork requires.
Chronological age counts calendar time from the actual date of birth. Adjusted age — also called corrected age — subtracts the number of weeks a baby was born before their expected due date, and is used for some children born preterm.
| Chronological age | Adjusted / corrected age | |
|---|---|---|
| Counted from | Actual date of birth | Expected due date |
| Typical use | Standardized test norms, eligibility, school placement | Developmental milestones for children born preterm |
| Applies to | Every child | Usually births before 37 weeks gestation |
| Stops being used | Never | Commonly between 24 and 36 months |
Most standardized speech and language tests are normed on chronological age, so unless the manual or the referring clinician says otherwise, chronological age is what belongs in the scoring. When a protocol does call for a prematurity adjustment, use the dedicated corrected age calculator, which reports chronological and corrected age side by side. The American Academy of Pediatrics explanation of corrected age covers the clinical background.
Clinicians often arrive searching for a particular publisher's tool — a Super Duper age calculator, a Home Speech Home age calculator, or the calculator built into a Pearson scoring platform. Those tools are made by their respective publishers and are not reproduced here.
What this page provides is the underlying calendar arithmetic they all share: the exact interval between a date of birth and an assessment date, in years, months and days. If you specifically wanted the Pearson tool, our Pearson age calculator alternative explains the difference and when a publisher's own tool is the right choice.
For developmental screeners rather than speech-language tests — ASQ, BRIGANCE or Gesell — see the child assessment age calculator. For any other standardized test, the age at testing calculator covers the general case.
Independence notice: Super Duper Publications, Home Speech Home and Pearson are trademarks of their respective owners. This site is not affiliated with, endorsed by, or connected to any of them, and does not reproduce their norms, scoring systems or scoring software.
This SLP age calculator performs the calendar subtraction only. How the result is used — the date that counts as the test date when testing spans sessions, whether remaining days are dropped or rounded, which age band applies and whether to adjust for prematurity — is set by each test's examiner's manual. Where the manual and this page differ, follow the manual.
Speech-language instruments whose manuals you should check include:
Check the edition that matches your record forms, and any additional requirements from your school district, health service or licensing body. This site is not affiliated with any test publisher.