🎂 Half Birthday Calculator
Select Your Birthday
What is a half birthday?
A half birthday is a day that is half a year before or after your actual birthday. While celebrating a half birthday is not as popular as celebrating an actual birthday, half birthday celebrations are not uncommon, especially for young children, those with birthdays around major holidays or Feb 29, and for anyone who just enjoys celebrating themselves!
Need help celebrating?
Download our free Half Birthday Cake Topper
How do you calculate a half birthday?
There are two common ways to calculate a half birthday.
+6 Months
The easy method is to just add 6 months to your current birthday and keep the day of the month the same.
e.g. If you were born on (Month 5) May 10, then your half birthday would be on (Month 5 + 6 Months = Month 11) November 10.
If you were born in a month with more days in it then the days in 6 months ahead has, then you would carry those days forward to the next month.
e.g. If you were born on (Month 5) May 31, then your half birthday would be on December 1. (Month 5 + 6 Months) would give you November 31, but since there's no November 31, you would carry the extra day foward to the next actual date, which is December 1.
+182.5 Days
The more exact method is to add 182.5 days (half a year or 183 days in a leap year) to your birthday. Generally you'll round up to 183 days to get to your half birthday.
The +182.5 Days method has more variability in it; if you subtract 183 days before your birthday, you'll end up with a different date than if you were just to add 183 days. You could also technically use either 182 days or 183 days in non-leap years, but for consistency, we recommend just sticking with adding 183 days.
With our free half birthday calculator, you don't need to worry about how to do the calculations, just select your birthday above to find out when your half birthday is and how many days away it is.
+6 Months
The easy method is to just add 6 months to your current birthday and keep the day of the month the same.
e.g. If you were born on (Month 5) May 10, then your half birthday would be on (Month 5 + 6 Months = Month 11) November 10.
If you were born in a month with more days in it then the days in 6 months ahead has, then you would carry those days forward to the next month.
e.g. If you were born on (Month 5) May 31, then your half birthday would be on December 1. (Month 5 + 6 Months) would give you November 31, but since there's no November 31, you would carry the extra day foward to the next actual date, which is December 1.
+182.5 Days
The more exact method is to add 182.5 days (half a year or 183 days in a leap year) to your birthday. Generally you'll round up to 183 days to get to your half birthday.
The +182.5 Days method has more variability in it; if you subtract 183 days before your birthday, you'll end up with a different date than if you were just to add 183 days. You could also technically use either 182 days or 183 days in non-leap years, but for consistency, we recommend just sticking with adding 183 days.
With our free half birthday calculator, you don't need to worry about how to do the calculations, just select your birthday above to find out when your half birthday is and how many days away it is.
Also see:
Age Difference Calculator
Age Calculator (for age on a specific date)
Days Old Calculator
Days Until I Turn...
Day of the Week Birthday Calculator