Age Calculator

The Age Calculator works out exact age in years, months, and days from a birth date — and can also calculate age as of any future or past date, or find the number of days between two dates.

How Age Is Calculated Precisely

Age in completed years equals the number of full birthdays that have passed since birth — a person born on July 15, 1990 turns 36 on July 15, 2026, but is still 35 the day before. Simple date-subtraction shortcuts (subtracting birth year from current year) get this wrong whenever the current date falls before the birthday in the current year, since that method doesn't account for whether the birthday has actually occurred yet this year.

Handling Leap Year Birthdays

People born on February 29 present a specific edge case, since that date only exists once every four years. Most legal and calendar systems treat February 28 (or March 1, depending on jurisdiction) as the effective birthday in non-leap years for purposes like turning a specific age. This calculator handles the leap-day edge case automatically rather than requiring manual adjustment.

Common Uses Beyond "How Old Am I"

• Legal age verification — checking whether a birth date meets a minimum age threshold for a service, contract, or age-restricted content.
• Retirement and financial planning — calculating years remaining until a specific retirement age or eligibility milestone.
• Medical and insurance contexts — determining exact age for dosage calculations or policy eligibility, where precision to the day can matter.
• Event and deadline planning — calculating the exact number of days between today and a future date, such as a wedding, deadline, or anniversary.

Age Reckoning Differs Across Cultures

Western age calculation counts from zero at birth and increments on each birthday. Traditional East Asian age reckoning systems instead count a person as one year old at birth, with age increasing on the New Year rather than an individual birthday — meaning the same person's "age" can differ by one or two years depending on which system is used. When precision matters across cultural contexts, clarify which age reckoning system is being referenced.