Calculators
Age Calculator
Find exact age in years, months and days, plus total weeks and days between two dates.
Dates
Results
Years
31
Months
3
Days
3
Total months
375
Total weeks
1,631
Total days
11,418
About this tool
The age calculator measures the exact calendar difference between a date of birth and another date. It accounts for month lengths and leap years instead of assuming every month has 30 days.
How to use
- Enter the date of birth.
- Optionally change the “Age at date” field. It defaults to today.
- Read years, months and leftover days, plus totals in months, weeks and days.
Formula and methodology
Years, months and days are counted on the calendar: if the day of month has not been reached yet, a month is borrowed and the actual number of days in the previous month is added. Total days use the UTC date difference so daylight-saving changes do not affect the count. Total weeks are total days divided by 7, discarding the remainder.
Worked example
Born on 15 March 2000 and measured on 15 September 2026 is 26 years, 6 months and 0 days. The same span is 318 months, 1,382 weeks and 9,680 days.
Frequently asked questions
Does this handle leap years?+
Yes. February 29 is treated as a real calendar day, so people born on a leap day are counted using the actual month lengths between the two dates.
Why do total months and years × 12 + leftover months match?+
Total months is the completed calendar months (years × 12 + remaining months). It is not total days divided by 30, which would be less accurate.
Can I calculate age on a past or future date?+
Yes. Change “Age at date”. The tool only requires that date to be on or after the date of birth.
Guides
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