Baekil Dol
Compare the date 100 days after birth with the first anniversary. The implementation adds 100 days to the birthdate, so this differs from counting the birthdate itself as day one.
- Runs in your browser
- Nothing is uploaded
- No signup; device limits apply
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How to use this tool
Select the birthdate carefully. If the family observes the hundredth day using inclusive counting, recognize the one-day difference before using this result to book an event.
Results and examples
Adding 100 days to a birthdate of 2026-01-01 gives 2026-04-11. The first anniversary uses the next year’s same month and day, subject to calendar normalization.
Limitations
- The hundredth day with inclusive counting is not the same as 100 days after birth.
- A February 29 anniversary needs a separate decision in a non-leap year.
Fields
| Field | Guidance and constraints |
|---|---|
| Date of birth | Check the unit and format displayed beside this field. |
Data handling
Processing stays in the current browser tab; the site does not upload tool input for the calculation itself.
Sources
Frequently asked questions
Does the hundred-day calculation include the birthdate?
Adding 100 days to a birthdate of 2026-01-01 gives 2026-04-11. The first anniversary uses the next year’s same month and day, subject to calendar normalization.
How should a leap-day anniversary be handled?
The hundredth day with inclusive counting is not the same as 100 days after birth. A February 29 anniversary needs a separate decision in a non-leap year.
