Age in Months Calculator
Calculate age in full calendar months and remaining days from a date of birth to today or any target date.
Calculate age in full months
This calculator reports completed calendar months plus remaining days. That matches the way parents, clinics and forms often write a young child's age: for example, 7 months and 12 days.
M is full calendar months and A is the day-of-month adjustment when the monthly birthday has not occurred yet.
Calendar months, not average months
- The result uses real calendar month boundaries.
- Dates on the 29th, 30th or 31st clamp to the last day of shorter months.
- Decimal months use 30.4375 days per month as an approximate supporting value.
- For premature infants this is chronological age, not corrected age.
Frequently Asked Questions
Sources and References
- WHO Child Growth StandardsWHO
- WHO Child Growth Standards trainingCDC
- DateMDN Web Docs
- ECMAScript Date ObjectsEcma International
Calculations are based on the listed reference sources. Links open in a new tab.
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