Age Calculator
Calculate your exact age in years, months, days, hours, minutes, and seconds from your birthdate.
Birthdate
The age calculator takes a birthdate and computes the exact age in every useful unit at the same time: years, months, weeks, days, hours, minutes, and seconds. The values update live, second by second, so you can see your age (or any object's age) ticking forward in real time. Works with any starting date - a person, a domain, a contract, an account, or a piece of equipment.
How the Age Calculator Works
Enter a birthdate in YYYY-MM-DD format, optionally add a time of birth in HH:MM:SS, and the calculator computes the elapsed time between that moment and right now. Every unit is calculated independently - "Total Months" is the total number of complete months, not the months left over after counting years. This makes each row useful on its own for forms, reports, or quick mental conversions.
- Calendar input: click the date field to open a calendar picker, or type the date directly. Add an optional time to make the calculation precise to the second.
- Unix timestamp input: paste a 10-digit (seconds) or 13-digit (milliseconds) Unix timestamp to use as the birthdate instead. The calculator parses it automatically.
- Live updates: the result rows update every second so you can watch the count tick. The "Total Seconds" row is the most dramatic - it ticks once per second forever.
If you need the gap between two specific dates rather than from a date to now, the date difference calculator handles that case. To project a future date by adding or subtracting a duration, use the date add/subtract calculator.
When to Use the Age Calculator
"What is my age in days?" is the canonical use case, but the same tool answers a lot of similar questions:
- Filling out forms that need precision: visa applications, medical records, and legal documents sometimes ask for an exact age in months or days, not just years.
- Pediatric and infant age: babies under 2 are commonly tracked in months and weeks. The calculator gives all units side by side without manual conversion.
- Pet age and life-expectancy comparisons: dog and cat owners often want the age in weeks or months for vet visits and food planning.
- Domain, account, and certificate age: paste a registration date or creation timestamp to see how old a domain, GitHub account, or SSL certificate is.
- Equipment and warranty checks: calculate how old a machine, vehicle, or appliance is in days or months to decide whether a warranty still applies.
- Personal milestones: "I'm 10,000 days old today" or "1 billion seconds old next week" are surprisingly fun reference points. The live ticking display makes them easy to spot.
How Each Unit Is Calculated
The calculator follows standard Gregorian calendar rules. Years and months are counted using calendar arithmetic, which means a year that crosses February 29 still counts as one year (not 365.25 days). Weeks, days, hours, minutes, and seconds are calculated as exact intervals from the birth moment to the current moment.
"Total Years" returns the integer number of complete years - someone born on May 28, 2000 is 25 years old on May 28, 2025 and still 25 on December 31, 2025. Similarly "Total Months" counts complete months: that same person crosses 300 complete months on May 28, 2025. If you need fractional ages (for example "25.4 years"), divide Total Days by 365.25.
Working With Historical Dates and Unix Timestamps
The calculator accepts any date - past, present, or future. A future birthdate (someone not yet born, or a domain that has not yet been registered) shows a negative age and the relative description "in X years". Historical dates work too: paste a date from 1900 to see how many days have passed since then.
To convert a Unix timestamp into a readable date before pasting it as the birthdate, the main timestamp converter does that instantly. To check the day of the week of a historical date, the week numbers tool shows the ISO week and weekday for any year.
Frequently Asked Questions
Enter your birthdate in the input above. The Total Days row in the result card shows the number of complete days between your birthdate and right now. For sub-day precision, add a time of birth in HH:MM:SS format and the calculator counts hours, minutes, and seconds toward the day total.
The calculator recomputes the elapsed time every second so the Total Seconds row visibly ticks forward. The other rows (years, months, weeks, days, hours, minutes) only change when their unit boundary is crossed, but they share the same live recalculation. Stop the tab from auto-updating by closing it or opening any other tool from the menu.
Yes. The calculation uses actual Gregorian calendar rules, so February 29 is counted when it applies and skipped when it does not. Someone born on February 29 still ages one year on February 28 in non-leap years (or March 1 depending on the platform's date library convention). The Total Days row reflects the true number of days, including any leap days the range crossed.
Each row is a single total in that unit, not a piece of a compound breakdown. "300 months" and "9131 days" can both describe the same span because months vary from 28 to 31 days. Pick whichever row matches the unit you need - they are all independently correct.
Yes. The calculator only cares about the starting date, not what the date represents. Use it to track the age of a domain (paste the WHOIS registration date), a vehicle (the manufacture date or purchase date), an SSL certificate (the issue date), a software account (the registration date), or any object with a known creation moment.
Yes. Paste a 10-digit (seconds) or 13-digit (milliseconds) Unix timestamp into the dedicated field and the calculator converts it to a calendar date automatically. This is useful when you have a creation timestamp from a database or an API and want to know how old that record is without converting the timestamp manually first.
Leave the Time field at 00:00:00. The calculator uses midnight as the default, which gives an accurate result to the day. The hour and minute totals will be slightly off (by up to 24 hours), but the years, months, weeks, and days will be exactly right. Add a real time only when you need second-level precision.
Enter the baby's birthdate and read the Total Weeks row directly. Pediatricians often track infants in weeks for the first year (developmental milestones are scheduled by week) and in months from one to two years old. Both rows appear simultaneously in the result, so you can quote whichever unit your doctor or form requires.
Yes. The calculator uses calendar arithmetic that works for any date - 1900, 1500, or even further back. Only if you paste a Unix timestamp do you need to be aware that pre-1970 dates correspond to negative timestamps. Calendar input (YYYY-MM-DD) works for any historical date the same way modern dates do.
The age calculator locks the end date to right now and updates every second, making it ideal for tracking a person's current age or live system uptime. The date difference calculator lets you set both dates manually and computes a static difference - use that one when you need the gap between two specific past or future dates rather than from a date to the present moment.