Baby Milestone Dates
Tracking your baby's growth milestones—100 days, 200 days, and yearly birthdays—helps families plan celebrations and capture memories. In Korean and other East Asian traditions, the 100-day celebration (Baek-il) is a major family event, while the 1st birthday (Dol) is celebrated with a special ceremony.
This calculator counts the birth date as Day 1, so the 100th day falls 99 days after birth. Yearly birthdays fall on the exact same date each year (or the nearest day for February 29 births).
Planning Tips
For a 100-day photo shoot, book the studio at least 2–4 weeks in advance as popular dates fill quickly. For a 1st birthday party, start planning 2–3 months ahead to secure the venue and catering.
Frequently Asked Questions
Yes. The calculator uses JavaScript's built-in date arithmetic, which correctly handles leap years. For babies born on February 29, the 1st birthday date will be set to March 1 in non-leap years by most browsers.
The calculator requires a birth date on or before today. For due date planning, you can use your expected due date as an estimate once the baby arrives.
Historically, the first 100 days were considered the most vulnerable period for newborns. Surviving this period was a milestone worth celebrating. Today, it is a joyful tradition for families to mark the moment with photos, food, and gatherings.