Age in Days, Weeks and Months Calculator
Convert an exact age into total days, approximate weeks, average months and hours.
Calculate age in days and weeks
Enter a date of birth and a reference date.
Different ways to express age
Calendar age is best for ordinary birthdays and official date comparisons. Total days and weeks are useful for baby milestones, project timelines, personal records and educational examples.
Do not treat average months as calendar months
The total-month figure is a conversion estimate. The exact calendar age shown alongside it remains the more precise date-based result.
Privacy
Input values are processed by JavaScript in your browser. The calculator code does not submit them to a server or place them in the URL.
Frequently asked questions
Are weeks exact?
Weeks are calculated from the exact total-day difference divided by seven.
Why are total months approximate?
Calendar months vary from 28 to 31 days, so total months use an average Gregorian month length.
Can I count to a past date?
Yes, as long as the selected date is on or after the date of birth.