Age Calculator
Enter a birth date and an optional target date (defaults to today) to see age in years, months and days, plus the total number of days.
How it works
Age is counted as completed years, then remaining months, then remaining days — the same way people state “32 years, 4 months.” Month anniversaries clamp when a month is shorter: 31 January plus one month is 28 February in a non-leap year (or 29 February in a leap year), not 3 March. If the birth date is 29 February, the anniversary in a non-leap year is treated as 28 February.
Formula
Age = completed years + remaining months + remaining days Total days = target date − birth date (in calendar days)
Worked examples
- born 2000-01-01, age at 2024-01-01 → 24 years, 0 months, 0 days (8,766 days)
- born 2023-01-31, age at 2023-02-28 → 0 years, 1 month, 0 days
Useful notes
- The target date must be on or after the birth date.
- Total days is an exact calendar-day count, not 365.25 × years.
FAQ
- How is age in months calculated when the birthday is the 31st?
- The next month’s anniversary is the last day of that month if the 31st does not exist. 31 January to 28 February in a non-leap year is one complete month.
- What happens for a 29 February birthday?
- In non-leap years the anniversary is 28 February, so someone born on 29 February 2000 turns 23 on 28 February 2023.
- Is the total-days figure exact?
- Yes. It is the number of calendar midnights between the two dates, including leap days that fall in the span.
Related tools
See all Date & Time tools.