Half Birthday Calculator
Find your half birthday, how many days until it and your 'and a half' age.
About this tool
Enter a birthday and the tool shows the next half birthday with its weekday, how many days away it is and the age you'll be (such as 31ยฝ). It also gives the date your half birthday falls on every year. Birthdays on the 29th, 30th or 31st move to the last day of a shorter month. Nothing is stored.
What a half birthday is
A half birthday is the day you're exactly six months past your birthday, when you turn "and a half". It's an old idea, especially popular for babies (their first half birthday is the six-month milestone) and for children whose real birthday falls at Christmas or in the summer holidays, so they can celebrate at school or with friends. This tool adds six calendar months, so 14 March becomes 14 September and 13 April becomes 13 October. Months have different lengths, so a birthday on the 31st can't always land on a 31st. Following the usual rule for adding months, it moves to the last day of that month: 31 August becomes 28 February, or 29 February in a leap year. Leap-day babies born on 29 February have their half birthday on 29 August. Some people prefer to count exactly 182 or 183 days (half of 365), which can move the date by a day or two. Either is fine, because there's no official rule. The age calculator gives your exact age, the countdown timer counts down to the day, and the day of the week tool shows the weekday for any date.
Frequently asked questions
How do I find my half birthday?
Add six months to your birthday. 14 March becomes 14 September.
What if my birthday is on the 31st?
If the month six months later is shorter, the half birthday moves to its last day: 31 August becomes 28 February.
When is a leap-day baby's half birthday?
On 29 August, six months after 29 February.
Is my data stored?
No. Nothing is saved or sent.