Korean 100-day calculator

Add 100 days to the date you started and you will be one day late. Count the starting date as day one.

For couple milestones and baek-il, the starting date is day one. Day 100 is 99 days later, and adding a full 100 lands you on day 101.

This page uses the starting-day rule for a couple’s milestones and a baby’s baek-il. Other kinds of date counting may use a different starting point.

Baek-il literally means “hundred days”. It is marked with a small party and a photo shoot, with the format chosen by the family.

Historically, high infant mortality made surviving the first hundred days an important milestone.

A celebration may include a table setting (백일상) with rice cakes and fruit, photos and a family gathering.

Dol is the first birthday. The traditional celebration includes extended family, a special outfit, and a table of food and rice cakes.

One tradition is doljabi (돌잡이): the baby is offered objects and whichever they grab is read as a hint about their future. Thread for a long life, money for wealth, a pencil for scholarship.

Note that dol is counted by date, not by days. Born on 20 October, the dol is 20 October the following year. If no leap day falls in between, that is day 366 because the date of birth is day one; with a leap day, it is day 367.

Many families hold the party on the weekend before, since a weekday dol is hard for relatives. The table above shows which weekday it falls on so you can plan around it.

Korean couples celebrate 100 days, 200 days, 300 days and 1,000 days alongside yearly anniversaries.

A thousand days is about two years and nine months after the start date. 500 days arrives roughly four months after the first anniversary.

Anniversaries by year work like dol: you match the date, not the day count. The day column therefore shows 366 for a one-year mark without a leap day, or 367 if the period includes one.

Count from the start date itself. Adding 100 days gives day 101.

A leap day shifts the day count, not the date. If 29 February falls inside the year, a one-year mark reads day 367 instead of 366. The anniversary still falls on the same month and day.

Born on 29 February? There is no such date in ordinary years. This calculator rolls forward to 1 March; some families pull back to 28 February instead. Check which date the family plans to celebrate.

Working out ages in Korean counting instead? That is a separate system — the Korean age calculator lays out all three.