What is chronological age?

Chronological age is the amount of time that has passed since a person was born, measured from the date of birth to a reference date such as today or the date of a test, usually written as years, months and days.

Should I round chronological age?

Do not round unless the test manual explicitly tells you to. Most manuals use the exact years and months and ignore the days.

What is the difference between chronological age and adjusted age?

Chronological age counts from the actual birth date, while adjusted age subtracts the weeks a child was born before 40 weeks' gestation and is commonly used for premature infants and toddlers.

Is my data stored anywhere?

No. All calculations happen in your browser. The optional recent calculations list is kept only in your own browser's local storage and can be cleared with one click.

How do you calculate chronological age by hand?

Write the test date above the date of birth as year, month and day. Subtract the days, then the months, then the years. If the days go negative, borrow one month and add the number of days in the month before the test month (or 30 days if your test manual says so). If the months go negative, borrow one year and add 12 months.

Calculators

Chronological Age Calculator

Calculate exact chronological age in years, months and days from birth and test dates

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Free tool for calculating exact chronological age in years, months and days, used by speech-language pathologists, psychologists, teachers and parents for

What it is

Screenshot of the Chronological Age Calculator homepage — slpagecalc.com, as visitors see it

Chronological Age Calculator is a free web tool that calculates exact chronological age in years, months and days from a date of birth and a test date. It serves speech-language pathologists, school psychologists, special education teachers, occupational therapists, pediatricians and early-intervention teams who need precise ages for standardized testing and assessment protocols.

The calculator offers both single child and batch processing modes, supporting the Y;M;D format used on assessment record forms. It includes two borrowing conventions found in test manuals (calendar months and 30-day months) and can process an entire caseload at once. All calculations run in the browser with no data stored on servers.

What it is built with

Single child age calculation
Batch processing for entire caseload
Y;M;D format output
Calendar months and 30-day month borrowing methods
Leap year support
CSV export
No data storage or accounts required

Pricing

Pricing model: Free