Academic achievement · Pearson

WIAT-4 Age Calculator

Chronological age in years;months.days for the Wechsler Individual Achievement Test, Fourth Edition, with the published age range 4:0 – 50:11 checked for you.

Birth Date

Test / Assessment Date

WIAT-4 at a glance

Full name	Wechsler Individual Achievement Test, Fourth Edition
Publisher	Pearson
Published age range	4:0 – 50:11
Age format	Years;months.days
Corrected age	Not applied in standard scoring.
Discipline	Academic achievement

The WIAT-4 is the achievement battery most often paired with a Wechsler cognitive measure in specific-learning-disability evaluations. Because it supports both age and grade norms, recording the exact age keeps the two comparisons defensible.

How the WIAT-4 wants the age entered

Enter the exact chronological age in years;months.days. The WIAT-4 offers both age-based and grade-based norms — age-based norms are the default for eligibility work unless the team documents otherwise.

The underlying calculation is the same for every instrument — complete years, complete months, then the leftover days. What differs is which part of it goes on the form. The calculator above reports all four figures at once, so you can copy the one the WIAT-4 manual asks for without recalculating:

Years;months.days — the full record-form format, e.g. 5;6.20
Years;months — complete units only, e.g. 5;6
Complete months — e.g. 66 months
Rounded to nearest month — e.g. 67 months (5;7), using the 15-day threshold

The exact date arithmetic, including month-end clamping and leap-day handling, is documented in the calculation methodology.

Worked example

A child born February 26, 2021 and assessed on September 15, 2026:

Chronological age: 5 years, 6 months, 20 days
Record on the WIAT-4 as: 5;6.20
Day remainder: 20 days — 15 or more, so a nearest-month rounding rounds up

Enter these exact dates above to reproduce the result. Every figure on this page is computed by the same library that runs the calculator, so the worked example and the tool can never disagree.

Other instruments

Same calculation, different recording format. These are the instruments most often administered alongside the WIAT-4:

Instrument	Age range	Age format
KTEA-3	4:6 – 25:11	Years;months.days
WJ IV	2:0 – 90:0 and older	Years;months.days
WRAT-5	5:0 – 85:0 and older	Years;months.days
WISC-V	6:0 – 16:11	Years;months.days
WPPSI-IV	2:6 – 7:7	Years;months.days
WAIS-5	16:0 – 90:11	Years;months.days

The full list is on the assessment instrument reference, and the assessment age calculator covers any instrument not listed individually.

Checked against the documented calculation method and its automated test suiteLast reviewed July 26, 2026Who publishes this

WIAT-4, Pearson are trademarks of their respective owners. AgeCalc is not affiliated with, endorsed by, or sponsored by any of them. Brand names are used descriptively to identify the assessment formats this calculator supports.

Frequently Asked Questions

Subtract the date of birth from the test date to get complete years, complete months, and the leftover days. For the WIAT-4 the age is recorded as years;months.days. Record the exact chronological age as years;months.days (e.g. 10;11.17). The norm table is selected by the age band that contains that age, so the partial month is never rounded up for the lookup. A child born February 26, 2021 and tested on September 15, 2026 is 5;6.20 — 5 years, 6 months, 20 days.

Pearson publishes the Wechsler Individual Achievement Test, Fourth Edition for ages 4:0 – 50:11. Outside that range the instrument has no norms, so a score cannot be computed even though the chronological age can. Always confirm the range in the edition of the manual you are scoring from — publishers revise ranges between editions.

No. For the WIAT-4 the partial month is not rounded up — record complete years and complete months, and report the leftover days separately where the form has a place for them. Rounding up moves the examinee into the next norm band and changes the standard score.

Prematurity correction is not part of standard WIAT-4 scoring — use chronological age from the date of birth. If a clinical team decides to report a corrected age alongside it for context, say so explicitly in the report so the score is not misread.

Standardized scores are read from age-banded norms. A one-month error can move an examinee into a neighbouring band and shift a standard score by several points — enough to change an eligibility decision at a cut-off. Recomputing the age from the birth date and test date, rather than reusing an age from an earlier report, is the reliable check.