AgeCalc

Assessment Age Calculator

Enter dates once — get years;months.days, complete months and the nearest-month rounded age together, plus corrected age for children born preterm.

Birth history
Format your instrument asks for

The full recording format (e.g. 10;11.17) used on Wechsler-family, CELF, PPVT and most record forms.

One Input, Every Format You Need

Educators, SLPs, and school psychologists record the same chronological age in different formats depending on the instrument. Instead of recalculating per form, enter the birth date and assessment date once here and copy whichever format the manual asks for:

  • Years;months.days (e.g. 5;4.26) — the standard record-form format, used by the Wechsler-family, CELF, PPVT and most age-banded batteries
  • Years;months (e.g. 5;4) — the same figure truncated, used for the norm-table lookup itself
  • Complete months (e.g. 64) — developmental screens, research forms and milestone tracking
  • Rounded to the nearest month (e.g. 5;5 / 65 months) — BRIGANCE Screens and other instruments that select a data sheet by rounded age

The format buttons only change which figure is emphasized — the arithmetic is identical and all four are always shown. Truncating and rounding are genuinely different rules: a 26-day remainder disappears under one and adds a whole month under the other. The instrument reference says which rule each assessment uses.

Worked Example

A child born January 10, 2021 and assessed on June 5, 2026:

  • Chronological age: 5 years, 4 months, 26 days
  • Years;months.days: 5;4.26
  • Years;months (truncated): 5;4
  • Complete months: 64
  • Rounded to the nearest month: 5;5 — 65 months, because the 26-day remainder is 15 or more

You can verify this in the calculator above — the output always matches the documented calculation method.

Children Born Preterm

Switch the birth history to Born preterm and enter the gestational age at birth to get corrected age alongside chronological age, without leaving this page. Corrected age is measured from the due date, and most guidance applies it to developmental expectations until the second birthday.

Whether a particular instrument uses corrected age is an instrument-specific question — the Bayley-4, ASQ-3, Denver II, PDMS-3 and BRIGANCE Screens do, most school-age cognitive and achievement batteries do not. Each per-instrument page states the rule, and the adjusted age calculator adds gestational and postmenstrual age.

Need a Specific Assessment?

The instrument reference lists the published age range, required age format and corrected-age rule for 40+ assessments, and each has its own calculator page that pre-selects the right format and checks the age against the published range. The most-used ones:

Format-specific pages: Brigance age calculator, Pearson age calculator, age in months, and the adjusted age calculator.

Checked against the documented calculation method and its automated test suiteLast reviewed Who publishes this

Brigance, 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

Assessment age is a child's chronological age on the exact date an assessment is administered. Standardized tests use it to look up the correct developmental norms, so it must be precise to the day — not rounded to the nearest month or year.
It depends on the assessment. Many manuals (including Brigance and most Pearson instruments) record age as years;months, such as 5;4. Some developmental screens and research forms ask for total months, such as 64. This calculator shows both so you can copy whichever your manual requires.
Down. Assessment convention counts only complete months: a child who is 5 years, 4 months, and 26 days old is recorded as 5;4. Rounding up would place the child in the wrong norm group.
No. AgeCalc is an independent tool and is not affiliated with, endorsed by, or sponsored by Brigance, Pearson, or any other assessment publisher. The display presets only reformat the same arithmetic; always confirm the required format in your assessment manual.
Most standardized assessment manuals specify chronological age from the actual birth date. For premature children, some early-intervention programs also track corrected age — our adjusted age calculator handles that case. When in doubt, follow your assessment manual or program guidelines.

Related Calculators

Brigance Age

Calculate chronological age in years;months for Brigance developmental assessments.

Pearson Age

Calculate age in the format required for Pearson assessments.

Age in Months

Calculate chronological age in months for testing and assessments.

Adjusted Age

Calculate adjusted (corrected) age for premature babies.