The Chronological Age Calculator finds age between a birth date and a reference date. It displays years, remaining months and remaining days, plus completed months, actual elapsed weeks and days, a calculation breakdown and a copyable record.
A whole-year age such as “8” omits the months and days. A result of “8 years, 4 months, 25 days” can also be written 8;04;25. The semicolons separate years, months and days; this is not a decimal number.
Use the calculator to check age on a record date, review date arithmetic for an assessment, reconstruct a historical age or calculate age at a future date. For an assessment, confirm the date and convention in the applicable manual. The calculator does not select test norms or determine eligibility.
Dates range from 0001-01-01 through 9999-12-31 using the proleptic Gregorian calendar, without switching historical calendar systems. Native date fields may follow your device's date display order; the breakdown uses YYYY-MM-DD. Changing an input or method clears the previous result until you calculate again. Reset clears birth, sets the reference to today and restores calendar mode.
The calculator itself does not save birth dates to the URL or browser storage. Copy result writes the dates, selected method, Y;M;D notation and actual total days to the clipboard so a copied record retains its context.
Chronological age describes age from birth to a specified date. This calculator reports years, remaining months and remaining days, such as 8 years, 4 months and 25 days, with the notation 8;04;25.
Choose it only when your assessment manual requires that convention. It borrows 30 days when the reference day is smaller than the birth day, then borrows 12 months when needed. It does not round up.
Calendar mode anchors each target month to the original birth day and uses the last day when that day does not exist. Thus 2020-02-29 to 2021-02-28 is 1 year, 0 months and 0 days. The separate 30-day method can differ.
No. It uses only birth and reference dates. It does not use gestational age, prematurity or test scores and cannot calculate corrected age, developmental age or norm-based test scores.
No extra day is added. Identical dates give zero age and zero elapsed days; the following date gives one day. Elapsed weeks are the actual total days divided by seven, with a day remainder.
指定日時点の年齢を年・月・日で計算。