Add your input
A birth date and optional comparison date.
Time keeper
Age calculator
Get a calendar-aware age rather than dividing total days by 365.
Privacy built inYour work stays with you
Exact age
36 years
7 months and 10 days
Total days lived
13,371
Next birthday
143 days
January 1, 2027
Your work stays private in your browser while you use this tool.
What does age calculator do?
The age calculator finds calendar age in years, months, and days on a chosen reference date. It also reports total elapsed days and the number of days until the next birthday.
- Input
- A birth date and optional comparison date.
- Result
- Calendar age and total elapsed days.
- Price
- Free
- Account
- Not required
How to use age calculator
Choose your settings
Get a calendar-aware age rather than dividing total days by 365.
Save or copy
Calendar age and total elapsed days.
A practical tip
Legal age rules can vary around leap-day birthdays and local jurisdictions.
When to use age calculator
Calculate a person's exact calendar age on an application or event date.
Find the total days between a birth date and a milestone date.
Check how many days remain until the next birthday from a chosen reference day.
Worked example
A concrete age calculator example
- Input
- Birth date: 2000-01-15; calculate on: 2025-03-20
- Result
- 25 years, 2 months, 5 days; 9,196 total days; next birthday in 301 days on January 15, 2026.
What to expect
How it works
Both dates are validated as UTC calendar dates. The calculator advances whole years, then whole months, then counts leftover days. Total days come from the UTC interval, and the next birthday reuses the birth month and day in the reference year or following year.
Know before using
Limits and edge cases
- A February 29 birthday rolls to March 1 in a non-leap year because of JavaScript date rollover; jurisdictions and families may recognize a different birthday date.
- The result is calendar arithmetic, not a legal determination of age, eligibility, gestational age, or age under a jurisdiction-specific rule.
Common questions
Age calculator FAQ
Is age calculator free to use?
Yes. Age calculator is free to use.
Does age calculator keep my work private?
Yes. Your work stays private while you use the tool — nothing you enter is uploaded.
Can I calculate age on a past or future date?
Yes. Replace the reference date with any valid date on or after the birth date; “Use today” is only a shortcut.
Why is total days different from years multiplied by 365?
Calendar years have 365 or 366 days, and the selected interval may also include partial years, so total elapsed days accounts for the actual leap days in the range.