An age calculator works out exactly how old someone is from a date of birth: whole years, months and days, plus the total days, weeks and hours lived and the date of the next birthday. Type a birth date above and the answer appears at once, with the working shown step by step.
Quick answer: your age is the number of whole years since the date of birth, then the whole months left over, then the leftover days. Someone born on May 15, 1990 is 36 years, 4 months and 23 days old on October 8, 2026, which is 13,295 days.
How to use this age calculator
- Type or pick the date of birth. The calendar picker works on phones; on a computer you can also type the month, day and year.
- Leave Age at this date empty to get the age today, or pick any past or future date to see the age on that day.
- Optionally add a second birth date to see the age gap between two people.
- Read the answer, the milestone table and the written working. Tap Copy result to paste the numbers, or Copy link to share the same setup.
| Input | What it means | Result you get |
|---|---|---|
| Date of birth | The first day of life (day 0) | Age in years, months and days |
| Age at this date | The day the age is counted on; empty means today | Age on that day, total days, weeks, hours |
| Second birth date | Another person to compare with | Age gap in years, months and days |
| Leap day option | Only shown for February 29 births | Birthday on March 1 or February 28 |
How old am I? The formula behind the age calculator
If you ask how old am I, the answer is a count of completed calendar periods. The age calculator uses three steps, the same method used on forms and by spreadsheet functions.
- Years: count the birthdays that have already happened: the end year minus the birth year, minus 1 if this year’s birthday has not arrived yet.
- Months: from the last birthday, add whole months until one more would pass the end date.
- Days: count the days from that month point to the end date.
The totals use a different route: total days = end date minus birth date, in whole days. Weeks are the days divided by 7 and hours are the days times 24. Dates are counted as calendar days, so time zones and daylight saving never shift the answer.
Worked example 1: born May 15, 1990, age on October 8, 2026
- The last birthday was May 15, 2026, so the age is 36 whole years.
- Adding 4 months to May 15, 2026 reaches September 15. A fifth month (October 15) would pass October 8, so the count stops at 4 months.
- September 15 to October 8 is 23 days.
- Total days: 13,295. Weeks: 13,295 ÷ 7 = 1,899 weeks and 2 days. Hours: 13,295 × 24 = 319,080.
The tool gives exactly 36 years, 4 months, 23 days for these dates, and the next birthday is Saturday, May 15, 2027, 219 days away.
Worked example 2: a month-end birth date
Take a birth date of January 31, 2000 and an age date of March 1, 2025. The last birthday was January 31, 2025. Adding one month gives February 28, 2025, because February has no 31st, so the calculator uses the last day of the month. Two months would reach March 31, which is too far. The leftover is March 1 minus February 28, or 1 day. The age is 25 years, 1 month, 1 day.
Age calculator by date of birth: how many days old am I?
People often ask how many days old am I, or how many weeks or hours. A year averages 365.2425 days, so a person turning 18 has lived 6,574 or 6,575 days and a person turning 30 has lived 10,957 or 10,958 days. The exact number depends on how many leap days fall in the lifetime. The table shows the exact range for every birth date from 1950 to 2000 (February 29 births excluded); weeks and hours are rounded averages.
| Age | Months | Days lived (range) | Weeks (about) | Hours (about) |
|---|---|---|---|---|
| 1 | 12 | 365 to 366 | 52 | 8,766 |
| 5 | 60 | 1,826 to 1,827 | 261 | 43,829 |
| 10 | 120 | 3,652 to 3,653 | 522 | 87,658 |
| 18 | 216 | 6,574 to 6,575 | 939 | 157,785 |
| 21 | 252 | 7,670 to 7,671 | 1,096 | 184,082 |
| 30 | 360 | 10,957 to 10,958 | 1,565 | 262,975 |
| 40 | 480 | 14,610 to 14,610 | 2,087 | 350,633 |
| 50 | 600 | 18,262 to 18,263 | 2,609 | 438,291 |
| 65 | 780 | 23,741 to 23,742 | 3,392 | 569,778 |
| 80 | 960 | 29,220 to 29,220 | 4,174 | 701,266 |
| 100 | 1,200 | 36,524 to 36,525 | 5,218 | 876,582 |
Age calculator in months and days
The age calculator in months and days suits babies and toddlers, when the months matter. A baby born on August 12, 2008 would be 18 years, 1 month, 26 days on October 8, 2026. Parents and clinics often use months for children under about 2 or 3; the total months tile in the result card gives the number to copy.
Age on a specific date: past, future or at a deadline
To find the age on a specific date, fill in the second date box. Most forms need exactly this: age on the first day of school, on a sports league cutoff date, on the day a policy starts, or on the date of an event. Past and future dates both work.
- Cutoff dates: leagues and schools often use age as of a fixed date such as August 1 or September 1. Enter that date as the age date.
- Age at an event: a person born February 3, 1950 was 74 years, 5 months and 1 day old on July 4, 2024.
- Planning ahead: enter a future date to see the age on the day a pension, license or insurance age limit applies.
Next birthday, days to go and the weekday
The result card shows the next birthday, the days until it and the age you will turn. A common year moves a fixed date forward one weekday and a leap year moves it forward two, so a birthday rarely lands on the same weekday two years in a row. For a birthday on October 8:
| Year | Weekday of October 8 | Type of year |
|---|---|---|
| 2026 | Thursday | common year |
| 2027 | Friday | common year |
| 2028 | Sunday | leap year |
| 2029 | Monday | common year |
| 2030 | Tuesday | common year |
| 2031 | Wednesday | common year |
| 2032 | Friday | leap year |
| 2033 | Saturday | common year |
| 2034 | Sunday | common year |
Between 1901 and 2099, a date after February repeats its weekday pattern every 28 years. Using the table, October 8 is next a Thursday in 2037, after the 2026 Thursday.
Leap year birthday: how old is someone born on February 29?
A person born on February 29 ages in whole days like everyone else, but the birthday in common years needs a rule. The UK and Taiwan treat March 1 as the legal birthday, according to Wikipedia’s article on leap day birthdays; other places and many apps use February 28. This age calculator lets you choose and defaults to March 1.
| Born February 29, 2000; age on February 28, 2025 | Age shown |
|---|---|
| Birthday counted on March 1 | 24 years, 11 months, 30 days |
| Birthday counted on February 28 | 25 years, 0 months, 0 days |
A person born on February 29, 2000 has a real leap day birthday only every four years: 2004, 2008, 2012, 2016, 2020 and 2024, which makes 6 by the end of 2024 even though the person is 24. Check the rule that applies to your document if the exact legal date matters.
Korean age calculator and East Asian age reckoning
In traditional East Asian age reckoning a baby is 1 year old at birth and gains a year at the New Year, not on the birthday. Korean age counting uses January 1, so the formula is current year minus birth year plus 1. A baby born on December 31, 2025 is 1 on that day and 2 on January 1, 2026, although the international age is 0.
| System | Rule | Age on Oct 8, 2026 if born May 15, 1990 |
|---|---|---|
| International (man age) | Whole years since the birthday | 36 |
| Korean age counting | 2026 − 1990 + 1; adds a year every January 1 | 37 |
| Traditional Chinese age | Counted from the lunar year; adds a year at Lunar New Year | 37 |
South Korea moved official documents to the international system: a law banning traditional ages on official documents took effect on June 28, 2023, as described in Wikipedia’s article on East Asian age reckoning. The Korean age line in the result card is for fun, family use and cultural context.
Chinese zodiac by birth year
The Chinese zodiac assigns one of 12 animals to each lunar year, and the age calculator shows yours with its element, such as Fire Horse for 2026. The animal changes at Lunar New Year, between January 21 and February 20, so a January or early February birth can belong to the previous animal. See Wikipedia on the Chinese zodiac for the traditions.
| Animal | Recent years (element) |
|---|---|
| Rat | 2008 (Earth), 2020 (Metal) |
| Ox | 2009 (Earth), 2021 (Metal) |
| Tiger | 2010 (Metal), 2022 (Water) |
| Rabbit | 2011 (Metal), 2023 (Water) |
| Dragon | 2000 (Metal), 2012 (Water), 2024 (Wood) |
| Snake | 2001 (Metal), 2013 (Water), 2025 (Wood) |
| Horse | 2002 (Water), 2014 (Wood), 2026 (Fire) |
| Goat | 2003 (Water), 2015 (Wood), 2027 (Fire) |
| Monkey | 2004 (Wood), 2016 (Fire), 2028 (Earth) |
| Rooster | 2005 (Wood), 2017 (Fire), 2029 (Earth) |
| Dog | 2006 (Fire), 2018 (Earth), 2030 (Metal) |
| Pig | 2007 (Fire), 2019 (Earth), 2031 (Metal) |
The calculator holds the Lunar New Year dates for 1900 to 2099 so it can pick the right animal for any birth date in that range. Lunar New Year was February 17 in 2026 (Fire Horse year begins) and is February 6 (Saturday) in 2027, so a birth before those dates belongs to the previous animal.
Star sign and generation
The age calculator also shows the Western star sign, which depends only on month and day. Sign boundaries vary by a day between books, so treat this table as the common modern version and use it for fun.
| Star sign | Dates |
|---|---|
| Capricorn | Dec 22 to Jan 19 |
| Aquarius | Jan 20 to Feb 18 |
| Pisces | Feb 19 to Mar 20 |
| Aries | Mar 21 to Apr 19 |
| Taurus | Apr 20 to May 20 |
| Gemini | May 21 to Jun 20 |
| Cancer | Jun 21 to Jul 22 |
| Leo | Jul 23 to Aug 22 |
| Virgo | Aug 23 to Sep 22 |
| Libra | Sep 23 to Oct 22 |
| Scorpio | Oct 23 to Nov 21 |
| Sagittarius | Nov 22 to Dec 21 |
The generation line follows the Pew Research Center, which defines Millennials as born 1981 to 1996 and Generation Z as born from 1997. The table shows ages during 2026, before and after the birthday.
| Birth year | Age before birthday in 2026 | Age after birthday in 2026 | Generation |
|---|---|---|---|
| 1940 | 85 | 86 | Silent |
| 1950 | 75 | 76 | Baby Boomer |
| 1960 | 65 | 66 | Baby Boomer |
| 1970 | 55 | 56 | Generation X |
| 1980 | 45 | 46 | Generation X |
| 1990 | 35 | 36 | Millennial |
| 2000 | 25 | 26 | Generation Z |
| 2010 | 15 | 16 | Generation Z |
| 2020 | 5 | 6 | Generation Alpha |
| 2025 | 0 | 1 | Generation Alpha |
Age milestones people check, and why exact dates matter
Official ages are counted from the birthday, not rounded, so one day can matter. The table lists common ages. Rules change and differ by state or country, so confirm the details with the agency concerned.
| Age | Typical meaning | Where |
|---|---|---|
| 16 | Driver’s license age in many US states (varies by state and license type) | United States |
| 18 | Age of majority in most places, and the US voting age | Many countries |
| 21 | Legal age to buy alcohol in every US state | United States |
| 62 | Earliest age to claim Social Security retirement benefits | United States |
| 65 | Medicare eligibility; Old Age Security starts at 65 | United States, Canada |
| 67 | Full Social Security age for people born in 1960 or later; Age Pension age | United States, Australia |
| 66 to 67 | State Pension age is rising from 66 to 67 between 2026 and 2028 (gov.uk) | United Kingdom |
Common mistakes when working out an age
- Subtracting years only. 2026 minus 1990 is 36, but if the birthday has not happened yet the age is 35.
- Mixing date formats. 03/04/2010 is March 4 in the US and April 3 in most other countries. The date picker removes the doubt.
- Using the wrong birth date. Someone born at 11 pm in one time zone is born the next day in another, so use the date on the birth certificate.
Frequently asked questions
8 quick answers
How do I calculate my age from my date of birth?
Subtract the birth year from the current year, then subtract 1 if your birthday has not yet happened this year. For the months and days, count whole months from your last birthday and then the leftover days. The age calculator does all three steps at once.
How old am I if I was born on January 1, 2000?
On October 8, 2026 a person born on January 1, 2000 is 26 years, 9 months, 7 days old, which is 9,777 days. They turn 27 on January 1, 2027.
How many days old am I?
Subtract your date of birth from today, counting whole days. A person aged 30 has lived 10,957 or 10,958 days, depending on leap days. The calculator shows the exact total days, weeks, hours and minutes.
How do I find my age on a specific date?
Enter the date of birth, then pick the date you want in the age at this date box. The result is the exact age on that day, in the past or in the future.
How do you calculate age in months and days?
Count the whole years first, then the whole months since the last birthday, then the remaining days. The total months are the years times 12 plus the extra months.
How is Korean age different from international age?
Korean age counting adds a year for everyone on January 1. A person aged 36 by international count is 37 or 38 in Korean counting, depending on whether the birthday has passed this year.
How old is someone born on February 29?
They age in whole years like anyone else, but the birthday in common years is counted on March 1 or February 28. The UK and Taiwan treat March 1 as the legal birthday.
Is my date of birth saved anywhere?
No. The age calculator runs in your browser and nothing is uploaded. The Copy link option only builds a link that contains the dates you typed.
Related calculators
- Date calculator: add or subtract days, weeks, months and years
- Days between dates calculator: days, weeks and working days between two dates
- Days until calculator: a countdown to any date
- Time calculator: add and subtract hours and minutes
- Due date calculator: pregnancy due dates
- Printable calendars and the full calculator list
Sources and further reading
- East Asian age reckoning (Wikipedia)
- Leap day birthdays (Wikipedia)
- Gregorian calendar and leap years (Wikipedia)
- Where Millennials end and Generation Z begins (Pew Research Center)
Last updated: October 2026.