A quarter birthday is three months after your birthday, when you are a quarter of a year older. A half birthday is six months after, and a three-quarter birthday is nine months after. Someone born on 10 January has a quarter birthday on 10 April, a half birthday on 10 July and a three-quarter birthday on 10 October.
Quarter birthday calculator
For your age on each day and how many days are left, use the half birthday calculator or the age calculator.
Quarter, half and three-quarter birthdays by month
| Birthday month | Quarter birthday (+3 months) | Half birthday (+6 months) | Three-quarter birthday (+9 months) |
|---|---|---|---|
| January | April | July | October |
| February | May | August | November |
| March | June | September | December |
| April | July | October | January |
| May | August | November | February |
| June | September | December | March |
| July | October | January | April |
| August | November | February | May |
| September | December | March | June |
| October | January | April | July |
| November | February | May | August |
| December | March | June | September |
Keep the same day of the month. If that day does not exist, use the last day of the month: 31 March has a quarter birthday on 30 June, and 30 November has a quarter birthday on 28 February (29 in a leap year). Our method page explains the rule.
Your age as a fraction
| Day | Age |
|---|---|
| Birthday | 30 |
| Quarter birthday | 30¼ |
| Half birthday | 30½ |
| Three-quarter birthday | 30¾ |
| Next birthday | 31 |
Young children often love saying their age this way: “I’m four and three-quarters!”
Is 9 months half a year?
No. Half a year is 6 months; 9 months is three-quarters of a year. Three months is a quarter of a year. For more conversions, see the months to years converter.
Ways to celebrate a quarter birthday
- For kids: a sticker chart that marks each quarter of the year, with a small treat at each one.
- For babies: 3 months and 9 months are popular photo milestones, alongside halfway to one at 6 months.
- For adults: a quarterly check-in on goals, or a small treat every three months.
- For friends: take turns choosing an activity each quarter birthday.
Most people celebrate the half birthday more than the quarter ones. See how to celebrate a half birthday for ideas that also work here.
Quarter birthday questions
What is a quarter birthday?
The date three months after your birthday, when you are a quarter of a year older.
When is my three-quarter birthday?
Nine months after your birthday, on the same day of the month, or the last day of the month if that day does not exist.
Is a quarter birthday a real thing?
It is an informal, fun idea rather than a tradition, used mostly by children and families. Half birthdays are much more widely celebrated.
How do I write a quarter birthday age?
Use a fraction: 4¼, 4½ and 4¾ for the quarter, half and three-quarter birthdays after turning 4.
Related guides
Last updated: 5 November 2026.