Age Calculator
Enter a date of birth to get an exact age in years, months and days, totals in weeks and days, the next birthday countdown and the generation.
The interactive tool loads here when JavaScript runs.
About this toolWhat is the Age Calculator?
Pick a date of birth and the Age Calculator shows how old that person is right now, down to the day: for example 36 years, 5 months and 13 days. Underneath it lists the same age as total months, weeks, days, hours and minutes, the weekday you were born on, how many days remain until the next birthday and which weekday it lands on, and the generation your birth year belongs to.
The "age on this date" field defaults to today in your own time zone, but you can set it to any date in the past or future. That answers questions such as "how old will I be on 1 June 2030?", "how old was my grandmother when she emigrated?" or "is this applicant 18 on the start date?".
People born on 29 February get a switch for how their birthday is counted in common years, 1 March or 28 February, because laws and families genuinely disagree on that point.
- Exact age in years, months and days with calendar-correct month ends
- Totals in months, weeks, days, hours and minutes
- Next birthday countdown with weekday
- Leap-day birthday convention switch
- Generation by Pew Research ranges and optional star sign
- Runs in your browser; dates are not sent anywhere
How to use the Age Calculator
- Enter the date of birth with the date picker or by typing it.
- Leave "Age on this date" at today, or choose another date to see the age then. Use the "Use today" link to go back.
- If the birthday is 29 February, choose whether common-year birthdays count on 1 March or 28 February.
- Read the exact age at the top, then the countdown, birth weekday and generation, and the table of totals.
- Copy the result or share a link that reopens the same dates.
Worked examples
Born 15 May 1990, checked on 28 October 2026
Input
Date of birth 1990-05-15, age on 2026-10-28
Output
36 years, 5 months, 13 days; 437 months; 1,902 weeks 1 day; 13,315 days; next birthday in 199 days on Saturday 15 May 2027
The 36th birthday was 15 May 2026, five whole months later is 15 October, and 13 days remain to 28 October. 1990 falls in Pew's Millennial range.
A leap-day birthday in a common year
Input
Date of birth 2004-02-29, age on 2025-02-28
Output
1 March setting: 20 years, next birthday tomorrow. 28 February setting: 21 years, birthday today
The only thing that changes is which day stands in for 29 February. On 29 February 2028 both settings agree: exactly 24 years.
Month ends that do not line up
Input
Date of birth 2025-01-31, age on 2025-03-01
Output
1 month, 1 day (29 days in total)
February 2025 has no 31st, so the first month is complete on 28 February and 1 March is one day later.
Background and insight
An age in years, months and days is counted the way anniversaries work. A year is complete on the birthday itself, a month is complete on the same day number of the following month, and anything after that is loose days. When the starting day does not exist in a shorter month, the month ends on that month's last day, so a child born on 31 January turns one month old on 28 February (29 in a leap year). Counting this way means the calculator agrees with what you would get by flipping a paper calendar, which is not the same as dividing a day count by 365.25.
Every date is treated as a plain calendar date rather than a moment in time, so daylight-saving changes and time zones cannot nudge a result by a day. The trade-off is that hour and minute totals are whole days multiplied by 24 and 1,440; they do not know the time you were born.
Generation labels follow Pew Research Center: Silent Generation 1928 to 1945, Baby Boomers 1946 to 1964, Generation X 1965 to 1980, Millennials 1981 to 1996 and Generation Z from 1997, which Pew reports have run to 2012. Pew has not fixed a range for the cohort after that, so births from 2013 are shown as Generation Alpha with a note that the range is common usage, not Pew's. The star sign uses the usual tropical zodiac dates and is there for fun.
Common use cases
Eligibility checks
Confirm whether someone meets an age limit on a specific date, such as a school entry cut-off, a sports age group or a retirement plan rule.
Paperwork and forms
Fill in "age at time of event" fields for insurance, immigration or medical history without counting on your fingers.
Birthday planning
See which weekday a coming birthday falls on and how many days are left to organise it.
Family history
Work out how old an ancestor was at a marriage, a census or a move by setting the "age on" date in the past.
Tips and limitations
- For the number of days or business days between two arbitrary dates, the Date Difference tool is the better fit; for adding a number of days to a date, use Date Arithmetic.
- Legal ages are usually reached at the start of the birthday, which is how this calculator counts. A few rules, such as some insurance "age nearest birthday" pricing, round to the closest birthday instead.
- East Asian age reckoning, where a baby is one at birth, gives a different number; this tool uses the international convention.
- Generation boundaries are research conventions, not official categories, and other organisations draw them a year or two differently.
Frequently asked questions
How do I calculate my exact age in years, months and days?
Count whole years to your most recent birthday, then whole months from that birthday to the same day number in later months, then the days left over. Born 15 May 1990 and checking on 28 October 2026 gives 36 years (to 15 May 2026), 5 months (to 15 October) and 13 days.
How old is someone born on 29 February in a non-leap year?
It depends on the convention. Some laws, such as Maryland's code, treat the birthday as 1 March in common years; many people and some agencies use 28 February. The calculator lets you pick either, and both give the same answer once a real 29 February comes round.
How many days old am I?
Subtract your date of birth from today as calendar dates. Someone born on 15 May 1990 is 13,315 days old on 28 October 2026. The calculator shows this along with weeks, hours and minutes.
What generation am I if I was born in 1996 or 1997?
By Pew Research Center's definitions, 1996 is the last Millennial year and 1997 is the first year of Generation Z. Generation X runs from 1965 to 1980 and Baby Boomers from 1946 to 1964.
Why is my age in months not my age in days divided by 30?
Months have 28 to 31 days, so a fixed divisor drifts. The calculator counts completed calendar months instead, the same way a birthday is counted.
Can I work out how old I will be on a future date?
Yes. Change "Age on this date" to any date, past or future, and every figure recalculates for that day, including the countdown to the following birthday.
Does the age calculator account for time zones?
It uses your device's local date for "today" and treats every date as a whole calendar day, so a time zone or daylight-saving change can never move the answer by a day. It does not use birth times.
Is there an in-depth guide to the Age Calculator?
Yes. “Age, Time Cards and Time Arithmetic: How the Counting Works” covers the background, how it works, common pitfalls and worked examples. Read the full guide.
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