Half-Birthday Countdown Calculator
Find your half-birthday — six months from your birthday — and count down the days until you celebrate it.
How it works
half-birthday = birthday + 6 calendar months · days left = next half-birthday − today
A half-birthday falls six calendar months after your birthday — a June 15 birthday gives a December 15 half-birthday. The calculator adds six months to your birth month and day (clamping the day when the target month is shorter), then finds the next time that half-birthday comes around. Only the month and day matter; the year you enter is ignored. It is popular for summer-born children who want a school-year party, and for marking the midpoint to the next birthday.
Worked example
A June 15 birthday: six months on is December 15. Checked on September 16, 2026, the next half-birthday is Tuesday, December 15, 2026 — 90 days away, or 12 weeks, 6 days.
Frequently asked questions
How is the half-birthday date worked out?
By adding six calendar months to your birthday, not 182 days. So an August 31 birthday gives a February 28 (or 29) half-birthday, since February is shorter — the day clamps to the end of the month.
Why would anyone celebrate a half-birthday?
Children born near a major holiday or in the school summer break often mark the half-birthday so friends are around, and it is a light-hearted way to note the midpoint to the next birthday.
Does it count today as zero?
Yes — on the half-birthday itself the countdown reads zero, and the day before reads one.
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This calculator is for educational purposes. Double-check important results before acting on them.