Chronological Age Calculator

Get a child's exact chronological age for test scoring, in years;months;days, with the method your test manual asks for. For everyday ages, use the age calculator.

Date of birth

Test date
Method
Days

Chronological age

e.g. born Aug 26, 2019 → 7;2;12 on Nov 7, 2026

The age appears here as you type.

Calculated in your browser. The dates you enter never leave this device.

Batch mode: a whole class at once

It uses the test date, method and day setting above. Nothing leaves your browser.

Related calculators

What chronological age is

Chronological age (CA) is the exact time since birth on the day of testing, written as years;months or years;months;days. Standardized tests use it to pick the right norms table, so a mistake of a few days can change a score near a cut-off.

Two ways to calculate it

Calendar method. Counts real calendar months and the days left over, the same way as our main age calculator.

Borrow-30 method. The hand method printed on many record forms: write the test date above the date of birth and subtract days, months and years. When the days come out negative, borrow one month as 30 days; when the months come out negative, borrow one year as 12 months.

The two methods agree most of the time and can differ by a day or two around month ends:

Date of birthTest dateCalendarBorrow-30
Feb 28, 2019Mar 27, 20267;0;277;0;29
Jan 31, 2018Mar 1, 20268;1;18;1;0
May 20, 2020Nov 6, 20266;5;176;5;16

What to do with the days

Manuals differ here. Some ask you to keep the days, some to drop them, and some to round to the nearest month. Pick Show, Drop or Round to match yours; Round moves up a month when the days are 15 or more.

Batch mode

Paste one child per line, with a name and a date of birth, to get every age at once and copy the results as CSV for a spreadsheet. Everything runs in your browser.

Frequently asked questions

How do you write chronological age?

As years;months, like 7;3 for 7 years and 3 months. Some record forms add the days: 7;3;12.

Should I round the days?

Follow your test manual. The calculator can show the days, drop them, or round to the nearest month, where 15 days or more rounds up.

What's the difference between chronological age and corrected age?

Chronological age counts from the date of birth. Corrected age, used for babies born prematurely, counts from the due date instead.

Is the test date counted?

The age is measured on the test date, the same way a birthday works: on the day a child turns 7, their chronological age is 7;0;0.

Is the list I paste in batch mode uploaded anywhere?

No. Batch mode runs entirely in your browser, and nothing you paste is sent anywhere.