Age Calculator
Enter a date of birth and get the exact age in years, months and days — plus a birthday countdown.
How to use
- Enter the date of birth.
- Optionally change the “as of” date — it defaults to today.
- Read the exact age, total days lived, and how many days remain until the next birthday.
Examples
Exact age today
Born 1990-05-15? As of 2026-08-16 that is 36 years, 3 months and 1 day — 13,242 days in total.
Age on a specific date
Set “as of” to a form deadline or event date to know the exact age on that day — useful for applications with age limits.
Korean age versus international age
Korea used three age systems at once until recently. International age counts completed years since birth. Korean age (세는나이) starts at one on the day you are born and adds a year every 1 January. Year age (연나이) is simply the current year minus the birth year. A person born in December could be 0, 2 and 1 on the same day under the three systems. This calculator returns international age, which is now the legal default.
Age for a visa or official form
Immigration forms, insurance applications and most legal documents ask for age in completed years as of a specific date, not as of today. Set the reference date to the date the form is evaluated rather than the date you fill it in. For anything with a cut-off — a discount band, an eligibility threshold — the day before the birthday and the day of the birthday give different answers, so the exact reference date matters.
Working out a date range in days
Beyond years and months the calculator gives the total number of days lived, which is the figure people use for day-count milestones such as a 10,000-day anniversary. Because it counts actual calendar days it absorbs leap days automatically, so the milestone falls where it really falls rather than where a 365-day approximation would put it.
FAQ
How is the age calculated?
Using the international convention: age increases by one on each birthday. Months and days are the calendar distance since the last birthday, so “36 years 3 months 1 day” means the 36th birthday has passed by 3 months and 1 day.
What about February 29 birthdays?
In years without a leap day, the age increases on February 28 — the last day of February — so a Feb 29 birth is exactly 1 year old on Feb 28 of the next (common) year. In leap years the real February 29 is used.
Can I calculate age at a past or future date?
Yes — change the “as of” date. The only restriction is that it cannot be before the date of birth.
Why does the result differ from some other calculators by a day?
Tools differ in whether they count the birth day itself. This calculator says you are exactly N years old on your Nth birthday, which is the standard legal interpretation.
What changed with the age unification law in 2023?
From 28 June 2023 the Civil Act and the Administrative Basic Act made international age the standard for laws and official documents, ending the default use of Korean age in administrative contexts. In everyday conversation Korean age has not disappeared, but on forms, contracts and government paperwork the number expected is now completed years since birth — the number this calculator gives.
Where is year age (연나이) still used?
In a few statutes that need a whole birth-year cohort rather than individual birthdays. Military service administration and the youth protection rules that set drinking and smoking ages work on year age, so everyone born in the same year crosses the line together on 1 January. School entry follows the same logic. Outside those specific laws, international age applies.
How do I convert to Korean age if someone asks?
Take the current year minus the birth year and add one. That gives Korean age directly without needing the birthday. The gap against international age is one year if your birthday has already passed this year, and two if it has not. Since June 2023 you will rarely need this for anything official, but it still comes up socially.