Half Birthday Calculator
Type in a birthday and get the half-birthday — the day exactly six months later — along with a countdown to the next one.
How it works
A half birthday sits six calendar months after the real one. The calculator shifts the birth month forward by six and keeps the same day of the month.
When the landing month is too short to hold that day — think an August 31 birthday pointing at February — it slides back to the last day of that shorter month.
It then looks at today and works out how many days until the next half birthday rolls around, so you know whether it's next week or most of a year off.
Frequently asked questions
What exactly is a half birthday?
It's the point halfway to your next birthday — six months on from the day you were born. Kids with summer birthdays often celebrate it so a school party lands mid-year.
How is the six-month date found?
The month jumps ahead by six while the day stays put, so March 15 becomes September 15. Nothing about the year of birth changes the month-and-day answer.
What about a birthday on the 31st?
If six months later lands in a shorter month, the date backs up to that month's final day. An August 31 birthday gives a half birthday on the last day of February.
How is the countdown measured?
It compares the half-birthday's month and day against today, using next year's occurrence if this year's has already gone by, then counts the whole days between.