Find any half birthday in seconds
A half birthday falls six months after a birthday — the day a child turns “seven and a half”. Families celebrate it for babies at six months, for children whose real birthday falls in the holidays, and just for fun. This half birthday calculator gives the date of the next half birthday from a date of birth, the age today in years and halves, and a table of the half birthdays to come.
It also handles the awkward cases: someone born on 31 August has no 31 February six months later, so the calculator shows the usual answer (the last day of February) and the exact middle of the year between birthdays.
How to use the Half Birthday Calculator
- Enter the date of birth.
- Leave From as today, or pick another date — for example to plan a party next year.
- Read the next half birthday, how many days away it is, and the half age.
- Check the table for the next six half birthdays, and copy the result if you want to share it.
Half Birthday Calculator features
Next half birthday
The date, the weekday and a countdown in days.
Half age
Shows “7½” once the half birthday has passed, with the exact years, months and days.
Month-end rule
Birthdays on the 29th, 30th and 31st move to the last day of a shorter month.
Exact midpoint
The true middle of the year between two birthdays, 182 or 183 days later.
How a half birthday is worked out
The common method adds six calendar months: 15 April becomes 15 October, and 2 January becomes 2 July. When the later month is shorter, the half birthday moves to its last day — 31 August becomes 28 February (29 February in a leap year), and 31 March becomes 30 September. This is the same rule the age calculator uses for month ends.
Some people prefer the exact midpoint of the year: half of the 365 or 366 days between two birthdays. That usually lands within a day or two of the calendar date. Both are shown, so you can pick the one your family likes.
Half birthday ideas
- Six-month baby celebration — a small cake, a photo with a “½” sign, and a check of the baby milestones for that age.
- Summer or holiday birthdays — children born in August or late December often celebrate at school on their half birthday instead.
- Half cake, half party — cut the cake in half, sing half the song, open half the presents.
- Count down to it with the countdown timer, and use the baby age calculator for a baby’s age in weeks and months.
Half Birthday Calculator FAQ
What is a half birthday?
The day six months after a birthday, when someone is exactly half a year older than at their last birthday — for example the day a child turns 7½.
When is my half birthday if I was born on 31 August?
There is no 31 February, so by the usual rule it is the last day of February: 28 February, or 29 February in a leap year. The exact midpoint method gives about 1 or 2 March.
How do I calculate my half birthday?
Add six months to your birthday: April 15 becomes October 15. If the result does not exist, use the last day of that month.
How old am I on my half birthday?
Your age at your last birthday plus a half — a 7-year-old turns 7½. The calculator shows your age in years and halves for any date.
Can I see half birthdays in 2026 or later years?
Yes. Set the From date to any day and the table lists the next six half birthdays from then.
When is a baby’s first half birthday?
Six calendar months after the birth: a baby born on 10 March has a first half birthday on 10 September. It is a popular time for a milestone photo, and many babies start solid foods around then — ask your health visitor or paediatrician.
Is a half birthday always exactly six months?
By the usual calendar rule, yes: it is the same day of the month six months later, or the month’s last day when that day does not exist. Because months have 28 to 31 days, the number of days in between varies from 181 to 184.
Does the calculator store my date of birth?
No. The dates are used in your browser only and are not saved or sent anywhere.