Age Calculator

Age is the elapsed time between a birth date and a reference date (usually today). Unlike simple subtraction of years, a precise age accounts for varying month lengths and leap years. The standard approach computes full years first, then remaining months, then remaining days — mirroring how people naturally state age: "25 years, 3 months, and 12 days."

Consider someone born on March 15, 1998, calculating age on June 11, 2026. Full years: from March 15, 1998 to March 15, 2026 is exactly 28 years. From March 15 to June 11 is 2 months and 27 days (March 15→April 15 = 1 month, April 15→May 15 = 2 months, May 15→June 11 = 27 days). Total age: 28 years, 2 months, 27 days. Total days lived: 28 × 365 + 7 leap days (2000, 2004, 2008, 2012, 2016, 2020, 2024) + 88 days into 2026 ≈ 10,308 days.

Leap years add complexity. A person born on February 29, 2000, has a legal birthday of February 28 or March 1 in non-leap years depending on jurisdiction. Age calculators typically treat February 29 births as February 28 for counting purposes in common years, ensuring the person reaches each annual milestone on the last day of February when the 29th does not exist.

Total days lived is useful for milestones, actuarial estimates, and curiosity. Divide total days by 365.25 for a decimal-year approximation. Next birthday countdown subtracts today's date from the upcoming birthday: if today is June 11 and the next birthday is March 15, 2027, that is 277 days away (since the 2026 birthday already passed).

Enter any birth date and optional "as of" date to get precise age in years, months, and days, total days lived, and days remaining until the next birthday. Use this for forms requiring exact age, planning milestone celebrations, or verifying eligibility cutoffs for programs with age requirements.