Chronological age calculator
Published On: 25/02/2026
Chronological Age Calculator
Calculate chronological age (years, months, and days) from a birth date to a reference date. This is commonly used in schools, healthcare, child development assessments, and official forms.
Inputs explained:
• Date of birth: the person’s birth date.
• Reference date: the date you want to measure age on (today, test date, appointment date, etc.).
The calculator returns age in years, months, and days, plus total days.
• Date of birth: the person’s birth date.
• Reference date: the date you want to measure age on (today, test date, appointment date, etc.).
The calculator returns age in years, months, and days, plus total days.
Leave it as today if you want the current age.
Note: “Include reference day” is sometimes used in school cutoffs or reporting rules. Most use the standard date difference.
Chronological Age Calculator — Description
The Chronological Age Calculator helps you calculate a person’s age from a date of birth to a specific reference date. It returns the age in years, months, and days, and also provides total days and an optional decimal-years estimate. This tool is useful for school eligibility, clinical assessments, developmental screening, and any situation where precise age calculation is required.
Simply enter a birth date and a reference date (today or any target date), then click calculate to get the results.