Enter a date of birth to find the half birthday — exactly six months on — plus when it next falls and how many days away it is.
What a half birthday is
A half birthday sits exactly six months from the day someone was born — the classic reason to look one up is a child with a late-December birthday who celebrates at school in June instead. Enter the date of birth and this calculator returns the half-birthday date, the next time it falls, and the countdown in days.
How to use it
- Enter the date of birth.
- Read the half-birthday date.
- Check when it next occurs and the days remaining.
The rule
A worked example
A birthday of 15 May gives a half birthday of 15 November — six calendar months on. The edge cases are the month-end ones: 31 August has no 31 February, so the half birthday lands on the last day of February — the 28th, or the 29th in a leap year. The calculator handles that clamping for you and counts the days to the next occurrence.