Baby milestones
Mark the six-month point and plan a small photo or family moment.
FREE HALF BIRTHDAY TOOLPRIVATE BY DESIGN
Half Birthday
Calculator
Find your exact half birthday date, weekday, countdown and half-year age by adding six calendar months to your birthday.
Find my half birthday →
No account. No date upload.
Exact dateMonth-length awareLive countdownDays until the dateHalf-year agePlus weekday
01
Start here
Enter your birth date
02
Your next half birthday
03 / QUICK ANSWER
When is my half birthday?
This calculator finds your half birthday by adding six calendar months to your birthday. Someone born on April 18 has a half birthday on October 18. The date is useful for baby milestones, classroom celebrations and a simple reason to make an ordinary day feel special.
- 1
Enter a birth date
The date stays in your browser and is not added to the URL.
- 2
Add six calendar months
The calculator accounts for month length and leap years.
- 3
See the next occurrence
Get the date, weekday, age and live day countdown.
04 / EXAMPLE
Birthday math without the guesswork.
Six months is not always 182 days. Month lengths and leap years change the exact day count, so calendar-month arithmetic gives a more useful answer.
BIRTHDAYAPR 18
+ 6 MONTHSHALF BIRTHDAYOCT 18
Half birthday dates: month-end and leap-year examples
We use the six-calendar-month convention, not a fixed 182-day offset. If the date does not exist in the target month, we use that month's final day. The calculator then finds the next annual occurrence on or after today.
| Starting birthday | Six months later | Why |
|---|---|---|
| April 18, 2026 | October 18, 2026 | The same day exists. |
| August 31, 2026 | February 28, 2027 | February has 28 days in 2027. |
| August 31, 2023 | February 29, 2024 | The target February is in a leap year. |
| February 29, 2024 | August 29, 2024 | August has a 29th day. |
First half birthday or next half birthday?
For a baby born less than six months ago, both dates are the same. For an older child or adult, the next half birthday is the upcoming annual celebration; the first half birthday is the original six-month milestone. Both are shown in your result.
These are calendar examples, not medical or legal age rules. Calculate your own date without uploading it. Method examples checked September 6, 2026.
05 / REASONS TO CHECKSchool celebrations
Give summer birthdays an alternative date during the school year.
A just-because day
Plan a message, cake or low-key surprise halfway to the next birthday.
06 / FAQ
Half birthday questions
When is my half birthday?
Your half birthday is six calendar months after your birthday. Enter your birth date above to find the next occurrence, weekday and countdown.
What is a half birthday?
This calculator defines a half birthday as six calendar months after a birthday. Calendar months differ in length, so this is not necessarily the exact midpoint in elapsed days between two birthdays.
How do I calculate my half birthday?
Add six calendar months to your birth month and keep the same day when that day exists. This calculator also finds the next occurrence after today.
What happens if the target month has fewer days?
The calculator uses the last valid day of the target month. For example, August 31 becomes February 28 in a common year or February 29 in a leap year.
Is a half birthday always 182 or 183 days later?
Not always. Calendar months have different lengths, and leap years can add a day. That is why this tool adds six calendar months instead of assuming a fixed number of days.
Does the calculator save my birth date?
No. The calculation runs in your browser. The current tool does not upload, store or add your birth date to the page URL.
Can I calculate a baby's half birthday?
Yes. Enter the baby's birth date to find the first or next six-month milestone and the number of days remaining.