🎂 Enter Your Birthday
Select your date of birth (Gregorian calendar)
Enter a valid date of birth (not in the future).
Defaults to today — change to calculate future/past age
Your Exact Age
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Age in All Units
Birthday Details
Zodiac & Generation
⚠️ Disclaimer: Age calculation uses the proleptic Gregorian calendar. Leap year birthdays (Feb 29) are celebrated on Feb 28 in non-leap years for age counting purposes. Chinese zodiac uses the traditional year boundary based on the lunar new year (approximately late January to mid-February). Zodiac sign dates are approximate; border dates vary by source. All results are for informational purposes only.
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Sources & Methodology
Age calculation uses the proleptic Gregorian calendar as defined by ISO 8601. Day-of-week calculation uses the Tomohiko Sakamoto algorithm (1993), mathematically verified against all dates from 1 AD to 9999 AD. Zodiac dates follow the standard Western tropical zodiac. Chinese zodiac uses the traditional 12-year cycle anchored to 4 BC (Year of the Rat).
Age Calculation Algorithm:
Years = current_year - birth_year (subtract 1 if birthday not yet reached this year) Months = completed months since last birthday (0-11) Days = remaining days after completed months Total Days Lived = (today - birth_date) in milliseconds / 86,400,000 Hours = Total Days * 24 | Minutes = Total Days * 1440 Leap Year Rule (Gregorian Calendar):
A year is a leap year if: (divisible by 4) AND (not divisible by 100, OR divisible by 400).
Examples: 2000 = leap (div by 400). 1900 = not leap (div by 100, not 400). 2024 = leap (div by 4, not 100).
Day of Week (Tomohiko Sakamoto, 1993):
Deterministic algorithm giving 0=Sunday through 6=Saturday for any Gregorian date.
Years = current_year - birth_year (subtract 1 if birthday not yet reached this year) Months = completed months since last birthday (0-11) Days = remaining days after completed months Total Days Lived = (today - birth_date) in milliseconds / 86,400,000 Hours = Total Days * 24 | Minutes = Total Days * 1440 Leap Year Rule (Gregorian Calendar):
A year is a leap year if: (divisible by 4) AND (not divisible by 100, OR divisible by 400).
Examples: 2000 = leap (div by 400). 1900 = not leap (div by 100, not 400). 2024 = leap (div by 4, not 100).
Day of Week (Tomohiko Sakamoto, 1993):
Deterministic algorithm giving 0=Sunday through 6=Saturday for any Gregorian date.
Last reviewed: April 2026
Birthday & Age Guide — Everything You Need to Know
Calculating your exact age sounds simple, but it involves careful date arithmetic — accounting for leap years, month lengths, and partial years. This guide covers how age is calculated, what your birthday reveals about you (zodiac signs, Chinese zodiac, generation), and interesting birthday facts.
How Exact Age Is Calculated
The exact age calculation follows these steps: first count the number of complete years elapsed since your birthday. Then count the number of complete months in the current partial year. Finally, count the remaining days. For example, if you were born on March 15, 1990 and today is November 20, 2025: you have completed 35 full years (since March 15, 2025 has passed), 8 full months (March to November = 8), and 5 remaining days (November 15 to November 20). Your exact age is 35 years, 8 months, and 5 days.
Western Zodiac Signs Reference
| Sign | Symbol | Dates | Element |
|---|---|---|---|
| Aries | ♈ | Mar 21 – Apr 19 | Fire |
| Taurus | ♉ | Apr 20 – May 20 | Earth |
| Gemini | ♊ | May 21 – Jun 20 | Air |
| Cancer | ♋ | Jun 21 – Jul 22 | Water |
| Leo | ♌ | Jul 23 – Aug 22 | Fire |
| Virgo | ♍ | Aug 23 – Sep 22 | Earth |
| Libra | ♎ | Sep 23 – Oct 22 | Air |
| Scorpio | ♏ | Oct 23 – Nov 21 | Water |
| Sagittarius | ♐ | Nov 22 – Dec 21 | Fire |
| Capricorn | ♑ | Dec 22 – Jan 19 | Earth |
| Aquarius | ♒ | Jan 20 – Feb 18 | Air |
| Pisces | ♓ | Feb 19 – Mar 20 | Water |
Chinese Zodiac 12-Year Cycle
| Animal | Recent Years | Traits |
|---|---|---|
| 🐀 Rat | 2008, 2020, 2032 | Clever, adaptable, resourceful |
| 🐂 Ox | 2009, 2021, 2033 | Dependable, patient, determined |
| 🐅 Tiger | 2010, 2022, 2034 | Brave, competitive, confident |
| 🐇 Rabbit | 2011, 2023, 2035 | Kind, diplomatic, elegant |
| 🐉 Dragon | 2012, 2024, 2036 | Charismatic, lucky, imaginative |
| 🐍 Snake | 2013, 2025, 2037 | Wise, intuitive, analytical |
| 🐴 Horse | 2014, 2026, 2038 | Energetic, passionate, adventurous |
| 🐐 Goat | 2015, 2027, 2039 | Creative, gentle, compassionate |
| 🐒 Monkey | 2016, 2028, 2040 | Witty, intelligent, innovative |
| 🐓 Rooster | 2017, 2029, 2041 | Observant, hardworking, courageous |
| 🐕 Dog | 2018, 2030, 2042 | Loyal, honest, kind |
| 🐖 Pig | 2019, 2031, 2043 | Generous, diligent, compassionate |
Generations by Birth Year
👥 Generation Reference (Pew Research / common definitions):
Silent Generation: 1928–1945 • Baby Boomers: 1946–1964 • Generation X: 1965–1980
Millennials (Gen Y): 1981–1996 • Generation Z: 1997–2012 • Generation Alpha: 2013–present
Note: Boundary years vary by researcher. These are the most widely cited ranges.
Silent Generation: 1928–1945 • Baby Boomers: 1946–1964 • Generation X: 1965–1980
Millennials (Gen Y): 1981–1996 • Generation Z: 1997–2012 • Generation Alpha: 2013–present
Note: Boundary years vary by researcher. These are the most widely cited ranges.
Leap Year Birthdays — Special Cases
People born on February 29 (leap day) only have an exact birthday once every 4 years (in leap years: 2024, 2028, 2032…). In non-leap years, most countries and organisations use February 28 as the legal birthday for age purposes. Some countries (such as the UK and Hong Kong) use March 1 for certain legal purposes. This calculator uses February 28 in non-leap years. A leap year is any year divisible by 4, except century years (divisible by 100) unless also divisible by 400.
Frequently Asked Questions
Enter your date of birth above. The calculator computes exact years by subtracting your birth year from today, minus 1 if your birthday hasn’t occurred yet this year. Then it counts completed months and remaining days. You also get your age in total days, hours and minutes lived.
Enter your birthday above and the calculator automatically shows days and weeks remaining until your next birthday. It accounts for leap years: if your birthday is Feb 29, it finds the next Feb 29 (next leap year) or Feb 28 (in non-leap years).
Enter your birthday above and the day of the week is shown instantly. The calculation uses the Tomohiko Sakamoto algorithm (1993), which is mathematically verified to give correct results for any Gregorian calendar date.
Your Western zodiac sign is determined by your birth month and day. Enter your birthday above to see your sign. The 12 signs are: Aries (Mar 21–Apr 19), Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces (Feb 19–Mar 20).
The Chinese zodiac repeats on a 12-year cycle. Enter your birthday above. Note: if you were born in January or early February (before Chinese New Year), you may belong to the previous year’s animal. This calculator applies the traditional Chinese New Year boundary for accuracy.
Leap day babies (born Feb 29) have an exact birthday only in leap years (every 4 years). In non-leap years, this calculator uses Feb 28 for age counting. Legal age definitions vary by country: UK uses March 1 for some legal purposes, while most other countries use Feb 28.
Enter your birthday above to see your total days, weeks, hours and minutes lived. The calculation counts every calendar day from your birth date to today, including all leap year days. For example, someone born January 1, 1990 has lived approximately 12,900+ days by April 2026.
Enter your birthday above for your generation. Common definitions: Silent Generation (1928–1945), Baby Boomers (1946–1964), Gen X (1965–1980), Millennials/Gen Y (1981–1996), Gen Z (1997–2012), Gen Alpha (2013–present). Boundary years vary by researcher.
A golden birthday (also called a lucky or champagne birthday) is when your age matches your birth day of the month. If you were born on the 17th, your golden birthday is when you turn 17. If born on the 25th, your golden birthday is at age 25. It can only happen once in your lifetime.
Based on US birth data, September birthdays are most common. September 9, September 19, and September 12 frequently rank as the most common dates. This is because nine months before September corresponds to December, coinciding with the holiday season. The rarest birthday is February 29, occurring only in leap years.
If today is before your birthday this year, subtract 1 from the year difference. For example: born July 15, 1995, today is April 17, 2026. Year difference = 2026 − 1995 = 31. Since July 15 has not yet occurred in 2026, subtract 1: age = 30 years. Then count months from July 15, 2025 to April 17, 2026 = 9 months, and days from April 15 to April 17 = 2 days. Age = 30 years, 9 months, 2 days.
A half birthday falls exactly 6 months after your birthday. For example, if born on March 15, your half birthday is September 15. Half birthdays are commonly celebrated for children born in summer months whose school-year birthday falls in vacation time, or in cultures and families that mark the halfway point between birthdays.
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