Find your exact age in years, months, days, and total weeks. Plus: next birthday countdown, zodiac sign, and milestone ages. Enter your birthdate and get the full picture instantly.
What the calculator shows for your birthdate
Enter your date of birth to get your exact age in years, months, and days — plus your total days lived, next birthday countdown, and zodiac sign.
Open Age Calculator →Calculating age sounds simple — subtract the birth year from the current year — but the precise calculation is more nuanced because it must account for whether your birthday has passed this year, the varying lengths of months, and leap years.
The proper method for exact age calculation has three components:
Step 1 — Years: Subtract birth year from current year. Subtract 1 if the birthday has not yet occurred this year. (Example: Born June 15, today is March 10 — the birthday hasn't happened yet this year, so subtract 1.)
Step 2 — Months: Count complete months elapsed since the last birthday. Subtract 1 if the current day of month is before the birth day of month.
Step 3 — Days: Count days from the last complete month boundary to today. If today's day number is greater than or equal to birth day, the count is straightforward. If not, borrow from the previous month.
This three-component breakdown gives you an exact age like "32 years, 7 months, and 14 days." An age calculator automates all this logic instantly, accounting for every calendar edge case.
Leap years add complexity to age calculations in two ways. First, for people born on February 29 (approximately 1 in 1,461 people, nicknamed "leaplings" or "leap day babies"), the birthday literally doesn't exist in non-leap years. Different legal jurisdictions handle this differently: in the UK, February 28 is considered the legal birthday in non-leap years. In New Zealand, it's March 1. For everyday purposes, leaplings typically choose to celebrate on February 28 or March 1 and count their "real" birthday every four years.
Second, for anyone calculating age across years that include February 29, the presence or absence of the leap day affects the total day count. A year spanning 2024's February (a leap year) will have 366 days instead of 365, making age calculations that span this period one day longer than the equivalent non-leap year calculation.
Modern age calculators handle leap year logic automatically using programming functions that correctly identify whether each year in the calculation range is a leap year. The calculation is transparent to the user but happens behind the scenes every time a date spanning February 29 is involved.
The Western "international age" system (you are 0 at birth and gain 1 year on each birthday) is not universal. Several Asian countries historically used different age counting systems, and the Korean traditional system is the most notable.
In the traditional Korean age system (세는나이, "counting age"), everyone is born at age 1 — the first year of life is considered complete at birth. More significantly, everyone gains a year of age on January 1st, not on their individual birthday. This means a baby born on December 31 is age 1 at birth and becomes age 2 on January 1 — gaining two "years" of age in just two days.
Korean traditional age is therefore always 1–2 years higher than international age. Someone who is 30 in the international system may be 31 or 32 in the Korean traditional system depending on whether their birthday has passed. South Korea officially adopted the international age system for legal purposes in June 2023, though the traditional counting system remains in cultural use.
Japan historically used the "kazoedoshi" system (similar to Korean age) but adopted the Western system in 1950. China used the traditional system as well, though the Western system is now standard in mainland China.
Age determines legal rights and responsibilities across virtually every domain of life. In the United States, these are the key age milestones:
Age 13: COPPA (Children's Online Privacy Protection Act) threshold — websites must get parental consent for users under 13. Also the minimum age for most social media platforms.
Age 16: Driving age in most US states (varies by state, 15 in some). Ability to consent to certain medical procedures in many states. Minimum working age for many jobs without restrictions.
Age 18: Full legal adulthood — right to vote, enter contracts, enlist in military without parental consent. The age of majority in all US states. Ability to purchase tobacco and lottery tickets federally.
Age 21: Legal drinking age (federal standard since 1984). Legal age to purchase cannabis in states where it is legal. Minimum age for car rental without young driver surcharges at many companies.
Age 25: Full brain development (prefrontal cortex matures). Lower car insurance rates. Most major car rental companies rent without surcharges.
Age 26: Last year to remain on parent's health insurance under the ACA (Affordable Care Act).
Age 62: Earliest age to claim Social Security retirement benefits (at reduced rates).
Age 65: Medicare eligibility begins. Traditionally considered the retirement age.
Age 67: Full retirement age for Social Security for those born 1960 or later.
Certain birthdays carry special cultural and personal meaning. The 16th birthday ("Sweet 16") is a traditional coming-of-age celebration in American culture, particularly associated with young women. The 18th birthday marks full legal adulthood in the US and most of the world, often celebrated as the transition from childhood to independent adulthood.
The 21st birthday carries particular weight in the US due to the drinking age, marking full access to adult social privileges. In Jewish tradition, the Bar Mitzvah (13 for boys) and Bat Mitzvah (12 for girls) mark religious adulthood. In Latino cultures, the Quinceañera celebrates a girl's 15th birthday as a milestone of young womanhood.
Major decade birthdays — 30, 40, 50, 60, 70 — are often celebrated with particular enthusiasm and occasionally mixed emotions, marking significant life chapters. The 100th birthday (centenarian milestone) is celebrated with messages from the President in the US and the King or Queen in the UK.
Subtract birth year from current year (minus 1 if birthday hasn't passed yet), count complete months since the last birthday, then count remaining days. An age calculator handles all this instantly, including leap year adjustments.
People born on February 29 don't have a birthday in non-leap years. Different countries treat this differently legally (Feb 28 in UK, March 1 in NZ). Leap years also add one day to any age calculation that spans a February 29.
In the traditional Korean system, you are born at age 1 and everyone gains a year on January 1st. This makes Korean age 1–2 years higher than Western age. South Korea officially adopted the Western age system for legal purposes in June 2023.
Key milestones: 16 (driving), 18 (voting, adulthood, contracts), 21 (alcohol, cannabis), 25 (car rentals, lower insurance), 26 (off parent's health insurance), 62 (Social Security eligibility), 65 (Medicare), 67 (full Social Security).