How to use this tool
Enter the baby's Gregorian birth date, choose whether birth counts as day 1, then select a one-month rule: 30 days, the same day next Gregorian month, or the same day in the next actual Chinese lunar month. Agree on the counting rule before arranging a gathering.
Rules and supported dates
Counting birth as day 1 gives birth date + 99 days for day 100; otherwise add 100 days. If the next month lacks the same day number, no replacement date is chosen. A gathering may be arranged separately.
Worked example
For a birth on 2024-01-01, counting birth as day 1 puts day 100 on 2024-04-09. Excluding the birth date gives 2024-04-10 instead.
Common question
What if the next month has no matching day?
The same-day rule reports no matching date rather than automatically replacing it with the month end. You may choose the separate 30-day rule, and a gathering need not occur on the exact milestone. This tool calculates family dates; it does not assess infant health or development.