Half birthday calculator - calculate and celebrate with your favorite celebrity!
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Half birthday

Half birthday is so popular.
The Queen of England celebrates her birthday twice a year and some countries celebrate name day. Half birthday is the way how to celebrate twice a year like a Queen!

What is Half birthday?

Half birthday, Minecraft cake

You may be asking when is my half birthday? Well half birthday allows you to celebrate twice a year as it is six months before or after your birthday. 1/2 birthday is a way of being able to have a party more often. This is especially exciting as babies will celebrate their first half birthday at only 6 months old!

Half birthday celebration

In our calculator you can find HB for you, your family or friends. Also you can find HB for more than 20,000 celebrities from our database. If someone has 20th half birthday, it means, he/she is 19 and half years. Not 20 and half. Its because we celebrate HB before birthday. E.g. A new born baby celebrate their 1st HB when he/she is roughly 6 months old and its 1st birthday is after that. You can celebrate your baby's 1/2 birthday with a onesie and half a cake to remember their special first party.

Maybe you can find, that your half birthday is on a special day. For example if you were born on 3rd July, your HB will be on 1st January. It will be the same as Tom Cruise.

How to calculate half birthday?

The easy way

The easiest way (but not the most accurate) is to add 6 months to your DOB. E.g. if you were born on 1st March, your HB is on 1st September. If you do not want to calculate, just have a look at this table:

Birthday Half Birthday
January 01 July 07
February 02 August 08
March 03 September 09
April 04 October 10
May 05 November 11
June 06 December 12
July 07 January 01
August 08 February 02
September 09 March 03
October 10 April 04
November 11 May 05
December 12 June 06

The exact way

A year has 365 days. Half of it is 182.5 days. It is 182 and a half days. For that reason, if you were born in the afternoon, you will celebrate HB a different day than if you were born in the morning (you celebrate on the same day). The problem is, that we do not know the hour of our birth.

Another problem is, that in a leap year with 366 days, you can celebrate HB on a different day.
On this webpage, we find HB an easy and very precise way. We calculate it from the Tropical year (Solar year), it is time that the Sun takes to return to the same position observed from Earth. It is the time, for one full orbit of the Earth around the Sun. This time is 365.24 days or 365 days and nearly 6 hours. Now its obvious, why we need leap year every 4th year :)

Half of year is 182.62 days (365.24 divided by 2) and we can round it to 183 days. Half birthday will be 183 days from your DOB. So you don't need to worry about the time of your birthday or leap year. If you do not want to calculate it yourself, then just use our calculator all you need to do is type in your date of birth and it will find out on what day your half birthday falls and in how many days so you can prepare a party.

Now that you know when to celebrate your and your friends half birthday, next time your friend has their half birthday tell them "Life is too short. Have a party and celebrate Half Birthday!!!".
Or just tell your friend "Happy Half Birthday" and watch his/her reaction :)
If you like pranks, prepare special 1/2 birthday present. such as one shoe, air pod, glove, sock and more. Especially if you have lost the pair and you have only one at home :)