Calculate your exact age in years, months, and days, plus days alive and your next birthday countdown.
Age is measured from your date of birth to today. A full year only completes when the same calendar date is reached, so someone born on 31 December is still 24 until that date arrives, regardless of how many days have passed since 1 January.
People born on 29 February (a date that only exists in leap years) legally celebrate their birthday on 28 February or 1 March in non-leap years, depending on the country. In England and Wales, the legal birthday is 28 February.
A fun milestone: you live through your 10,000th day at around age 27 years and 4 months. Your 20,000th day comes at around age 54 years and 9 months.
The legal adult age varies: 18 in the UK, US, and most of Europe. 16 for some rights in Scotland. 21 for certain activities in some US states and other countries. Retirement ages also vary; the UK pension age is rising to 67 by 2028.
For official documents, age is almost always calculated as of the date of application or assessment, not a future date. Use today's date unless the form specifically says otherwise.
For premature babies, doctors distinguish between chronological age (time since birth) and corrected or adjusted age (time since the expected due date). Corrected age is used for developmental milestones up to around age 2.
Enter your date of birth to calculate your exact age in years, months, and days — plus your total days lived and a countdown to your next birthday.
Born 15 March 1990
Exact age calculated to today: years, months, days and total days lived
Born 1 January 2000
Turned exactly 25 years old on 1 January 2025
Born 29 February (leap year)
Official birthday counted as 28 February or 1 March in non-leap years
Calculate age from 10 May 1995 to 10 August 2025
Age: 30 years, 3 months, 0 days
Different cultures count age differently. In traditional East Asian reckoning, a person is considered 1 year old at birth (not 0) and ages increase on New Year's Day rather than on birthdays. This means a baby born on 31 December is considered 2 years old just two days later. South Korea officially abolished this system in 2023 and now uses the international standard.
Your age is calculated by counting the number of complete years, months, and days between your date of birth and today. A full year only completes when the same calendar date is reached — so a person born on 15 March is still 29 until 15 March arrives, regardless of how close January is to finishing.
29 February only exists in leap years (every four years). In non-leap years, people born on this date officially celebrate on either 28 February or 1 March depending on the country. In England and Wales, the legal birthday in non-leap years is 28 February. The calculator handles this by counting from the closest valid date.
The total days alive is shown directly below your age. You can calculate it manually by subtracting your date of birth from today and dividing by 86,400 (seconds in a day). Milestones worth knowing: your 10,000th day falls around age 27 years and 4 months; your 20,000th day around age 54 years and 9 months.
Yes. Simply enter the other person's date of birth. The calculator always measures from that date to today, so it works for any person or even non-human things with a known creation date — animals, businesses, buildings, or historical events.
Chronological age counts from the birth date. Corrected age (also called adjusted age) counts from the original due date. For premature babies, doctors use corrected age to assess developmental milestones, because a baby born 8 weeks early effectively has 8 fewer weeks of development than their birth date suggests. Corrected age is typically used until around 2 years.