Calculator
When will my baby be 100 days old?
Enter a birth date to see your baby’s exact age today and the dates of every monthly birthday, the 100th day, the half birthday and the 1,000th day. Download them to your calendar in one file.
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How the dates are counted
Monthly birthdays fall on the same day of each month. If a baby was born on the 29th, 30th or 31st and a month is too short, the last day of that month is used. The half birthday is six calendar months after birth.
For the 100th day, the day of birth is counted as day 1, which is how most 100-day celebrations count, including the Korean baek-il. Some families count the day after birth as day 1, which makes the date one day later. The 500- and 1,000-day dates count full days since birth.
Dates worth a photograph
Monthly photographs are easier to keep up if the date is already in your calendar. Use the same chair, blanket or toy each month so the growth is obvious. Add one sentence about what is new.
These are calendar dates for celebrating and remembering. They are not developmental milestones. For questions about your baby’s development, including adjusted age for babies born early, ask your pediatrician.
Common questions
How do I calculate 100 days from my baby’s birth?
Count the day of birth as day 1 and add 99 days. A baby born on 1 January reaches day 100 on 10 April, or 9 April in a leap year.
When is 1,000 days old?
1,000 days is about two years and nine months after birth. The calculator gives the exact date.
What is a golden birthday?
It is the birthday when the age matches the day of the month, such as turning 7 on the 7th.
Save a memory on each of these days.
A photograph and one sentence, kept on your baby’s timeline.