Half Birthday Calculator
Enter your birthday to see your next half birthday with a countdown, plus your previous half birthday and next birthday for easy planning.
What Is a Half Birthday?
A half birthday is a date that falls about six months before or after your birthday—an easy way to mark a mid-year moment.
It’s often used for small celebrations, classroom treats, or as a backup celebration date when a birthday lands on busy holidays. Social media and party culture helped the idea spread because it’s simple, shareable, and gives you another reason to celebrate.
Learn more on Wikipedia: Half-birthday
How to Use This Half Birthday Calculator
We calculate your half birthday by adding six months to your birthday and adjusting for shorter months when needed.
- Next Half Birthday shows the next upcoming half birthday from today.
- Previous Half Birthday shows the most recent half birthday that already passed.
- Days until / days since help you plan reminders and celebrations.
- Next Birthday is included for quick comparison and planning.
If your birthday is on a month-end date (like the 31st), the half-birthday may shift to the last valid day of the target month.
Half Birthday Examples
Standard Date
Birthday: March 10 → Half Birthday: September 10
Month End Adjustment
Birthday: August 31 → Half Birthday: February 28/29
FAQ
Why did my half birthday move to the 28th or 29th?
Some months have fewer days. If the target month doesn’t have the same day number (like the 31st), the half birthday falls on the last valid day of that month.
How can I use this to set reminders or plan ahead?
Add the Next Half Birthday date to your calendar and set reminders (for example, 7 days and 1 day before). Use the countdown to plan a small celebration, booking, or mid-year check-in.
Is a half birthday worth celebrating?
Yes. A half birthday is a fun, low-pressure mid-year milestone—especially popular for kids, for people whose birthdays fall on busy holidays, or for a simple mid-year reset. Popular ways to celebrate include a small get-together or afternoon tea, a “half cake” or cupcakes, a quick half-year photo update, a mid-year goals check-in with a calendar reminder, a small gift or experience, or a favorite meal with friends (often on the nearest weekend).