Birthday Calculator
Enter your date of birth to instantly find your exact age in years, months and days, count the days until your next birthday, see what day of the week you were born, your Western zodiac sign, Chinese zodiac animal, generation, and birthstone. You can also change the reference date to calculate age on any past or future date.
How the age calculation works
The calculator subtracts the birth date from the reference date using the Gregorian calendar. First it finds the number of complete years by checking whether the current month and day have already passed the birth month and day in the reference year. It then counts the remaining months and days on top, adjusting for the variable length of each month. The result is the same method used on official documents: someone born on June 15, 1990 who is checked on June 14, 2026 is still 35, not yet 36.
Leap year birthdays
People born on February 29 only have a matching date every four years. For birthday countdown purposes, this calculator uses March 1 in non-leap years as the accepted civil birthday. This follows the convention used in most countries when a legal age threshold must be calculated for a February 29 birth.
Western and Chinese zodiac signs
The Western zodiac divides the year into 12 signs based on the position of the sun on the birth date, starting with Aries (March 21) and cycling through to Pisces (February 18). The Chinese zodiac runs on a 12-year animal cycle rather than a monthly one: each birth year is associated with one of 12 animals including Rat, Ox, Tiger, Rabbit, Dragon, Snake, Horse, Goat, Monkey, Rooster, Dog and Pig. The cycle repeats every 12 years, so years ending in the same digit share an animal (e.g. 2000, 2012 and 2024 are all Dragon years).
Birthstones and what they mean
Traditional birthstones are gemstones associated with each calendar month, originating from the twelve stones of the high priest's breastplate described in the Book of Exodus and later standardised by the American National Retail Jewelers Association in 1912. Each stone is said to carry symbolic meaning: garnet (January) represents loyalty, amethyst (February) stands for clarity of mind, diamond (April) signifies strength, and ruby (July) evokes passion. Many months have an alternative modern stone alongside the traditional one.
Generation birth year ranges
| Generation | Birth years | Age in 2026 |
|---|---|---|
| Greatest Generation | Before 1928 | 98+ |
| Silent Generation | 1928-1945 | 81-98 |
| Baby Boomers | 1946-1964 | 62-80 |
| Generation X | 1965-1980 | 46-61 |
| Millennials (Gen Y) | 1981-1996 | 30-45 |
| Generation Z | 1997-2012 | 14-29 |
| Generation Alpha | 2013 or later | Under 14 |
Generational cohort definitions used by most sociologists and market researchers.
Frequently asked questions
How many days until my next birthday?
Enter your date of birth and today's date in the calculator. The "Days until next birthday" field counts the exact number of calendar days between today and your next birthday. If today is your birthday, it shows 0.
What if I was born on February 29?
The calculator treats March 1 as your birthday in non-leap years, which is the standard civil convention used in most legal and administrative contexts. In leap years your actual February 29 birthday is used.
What is a half-birthday and how is it calculated?
A half-birthday falls exactly six months after your birth date. The calculator adds six months to your birth month and uses the same day of the month, adjusting to the last day of the month when necessary (for example, someone born on August 31 has a half-birthday on February 28 or 29).
How is the decimal age calculated?
Decimal age divides the total number of days you have lived by 365.25 (the average Gregorian year length that accounts for leap years). It is used in paediatric medicine and developmental research to compare children's ages precisely.
Can I calculate someone else's age or a past date?
Yes. Change the "Age as of" field to any date, past or future. For example, set it to a graduation date to find out how old you will be then, or to a historical date to find someone's age at a point in history.
Why does my age show one year less than I expected?
The calculator uses the conventional Western system: you do not gain a year until your birthday has actually passed. If today is June 14 and your birthday is June 15, you are still the previous age even though you turn the next age tomorrow.