Half Birthday Calculator

Enter your birthday to find your half birthday — the date exactly six months away — plus a countdown to the next one.

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What is a half birthday?

Your half birthday is the day exactly halfway to your next birthday — six months from the day you were born. If your birthday is March 10, your half birthday is September 10. It's a light-hearted excuse to celebrate, and it's a favorite for kids whose real birthdays land on a holiday or during summer break, so they can still have a party at school.

How it's calculated

The calculator adds six calendar months to your birth date. When that would land on a day that doesn't exist — like February 31 — it rolls back to the last real day of the month, so your half birthday is always a genuine date.

A half birthday is just for fun — there's no official rule, but adding six months is how it's most commonly figured.