Working out an exact age by hand is easy to get wrong. Leap years, uneven months, and birthdays near month-end all trip up simple subtraction. Enter a birth date below and this age calculator gives the exact age in years, months, and days, plus totals in weeks, days, hours, and seconds, days until the next birthday, and a few fun facts.
Enter your birth date above to see your exact age.
How to use
- Pick the birth month, day, and year from the dropdowns.
- Leave the "age at" date on today, or pick another date to see an age on that date.
- If born on February 29, pick the February 28 or March 1 setting for other years.
- Read the result. The exact age, totals, next birthday, and fun facts update as you change a date.
- Use Copy result to copy the result as text, or Copy link for a link that prefills the same dates when opened.
How we calculate
The calculator counts completed calendar years first, then completed calendar months, then leftover days. A year counts once the birthday for that year has passed; a month counts once the same day-of-month in the next month has passed.
One way to check by hand is the same order: count whole years to the most recent birthday, then whole months from there, then leftover days. Another way is to count the total days between the two dates and then work out how many whole calendar years and months fit inside that span. Both routes give the same answer when calendar months are counted properly, because months have uneven lengths.
Worked example: born November 15, 2006, age on March 10, 2026. November 15, 2006 to November 15, 2025 is 19 years. November 15 to February 15 is 3 months. February 15 to March 10 is 23 days. Result: 19 years, 3 months, 23 days.
Month-end rule
When the birth day does not exist in a later month, the last day of that month counts as the month's anniversary. Born January 31, the age on February 29 in a leap year is 1 month, 0 days, and the age on February 28 in other years is also 1 month, 0 days. The same rule gives February 28 to March 31 as 1 month, 3 days: February 28 to March 28 is the completed month, and March 28 to March 31 adds 3 days.
February 29 birthdays
If born on February 29, the toggle picks whether other years count the birthday as February 28 or March 1. The choice changes the year count on those two dates. For a February 29, 2000 birth date, the age on February 28, 2026 is 26 years, 0 months, 0 days under the February 28 setting, and 25 years, 11 months, 27 days under the March 1 setting. On March 1, 2026 the two settings give 26 years, 0 months, 1 day and 26 years, 0 months, 0 days.
Nearest birthday
"Nearest birthday" rounds up after the half-year, the convention insurers use. If more than half the span since the last birthday has passed, the nearest birthday is the next one. At the exact midpoint it also rounds up.
Milestones and day counts
The birth date counts as day 0, so the 10,000th day of life falls 10,000 days after it. One billion seconds is 11,574 days plus 1 hour, 46 minutes, 40 seconds after midnight on the birth date, and the tool shows that date and time. "Next milestone birthday" uses these ages: 1, 5, 10, 13, 16, 18, 21, 25, 30, 40, 50, 60, 70, 80, 90, 100, then each multiple of 10 after 100.
Today, seconds, zodiac, and birthstones
The default "age at" date is today on the device's local calendar, not GMT. Totals for hours, minutes, and seconds count from midnight on the birth date. Because birth time is not asked, these are date-difference totals, not a count of exact seconds alive. Zodiac signs use standard calendar ranges; a birth date near a sign boundary can fall in either sign depending on year and time zone, so treat the sign as a fun label. Birthstones follow the modern list; a few months have more than one recognised stone, and the tool shows those alternates.
FAQs
Can I find my age on a specific date?
Yes. Pick any date in the "age at" field, past or future, and the tool gives the age on that date. Leave it on today for a current age.
What if I only know the birth year, not the exact date?
Subtract the birth year from the current year for an approximate age, but without the month and day the result can be off by almost a year. The tool needs a full date for an exact age.
Are the hours, minutes, and seconds exact?
They are date-difference totals counted from midnight on the birth date. Because birth time is not asked, they are not a count of exact seconds alive. The live seconds counter on the result counts the same way, from midnight on the birth date to right now.
What happens with February 29 birthdays?
In years with no February 29, pick whether the birthday counts as February 28 or March 1. The toggle sits under the date fields and only affects February 29 birthdays. The age changes with the setting on those two dates, as shown in the February 29 section above.
Why does January 31 to February 29 count as a full month?
Because months are counted as completed calendar months, and the last day of a month maps to the last day of the next month. January 31 to February 29 covers the whole month of February in a leap year, so it counts as 1 month. The same rule makes February 28 to March 31 equal to 1 month and 3 days.
How does the tool show age for a baby?
For a child under 2, the result also shows age in years, months, weeks, and days. Weeks are easier to follow in the first months, so a 10-day-old shows as 0 years, 0 months, 1 week, 3 days.
What is a nearest birthday, and why does it round up?
The nearest birthday is whichever birthday, last or next, sits closer to the "age at" date. After the half-year point it rounds up to the next birthday, the convention insurers use when an age is rounded. At the exact midpoint it also rounds up.
Do other cultures count age differently?
Yes. In most Western countries, age rises on each birthday, and this calculator uses that system. In the traditional Chinese system, a child counts as 1 year old at birth, and age rises at the New Year instead of on the birthday. The two systems can differ by 1 or 2 years for the same person.