K-pop idol birthdays by month: July is the thinnest, March the fullest

Which month has the most K-pop idol birthdays? We counted every member of the 263 K-pop groups we hold — 1303 people with a birth date on record.

Months are not the same length, so counting raw totals makes February look small every time. Each month below is put on a per-day footing first. An even year would give every month 1.00x. March comes out at 1.199x and July at 0.685x.

Every month

Is that just chance?

With 1303 people spread over twelve months, some months will run ahead of others by luck alone. So we scattered the same number of birthdays evenly across the year 10,000 times, with a fixed seed (20260904) so anyone re-running this gets the same figure, and asked how often the gap between the fullest and thinnest month came out as wide as ours. It did 1.1% of the time.

That is below our 5% line, so the gap is not explained by chance alone. What causes it, we did not measure.

One date we had to remove

Before any of the above, we took out 1 January. It held 14 people — 3.89 times an average day. That is the date sources use when only the birth year is known, so it is a record-keeping artefact rather than a run of January births. Including it, the chance figure was 1%; removing it, 1.1%. The finding survives either way, but the honest table is the one without it.

What this is not

This is a count of 1303 people, not a statement about anyone. It does not say a month is lucky, and it does not say why the months differ — seasonal birth patterns in Korea and the way our roster was assembled would both produce a gap like this, and we did not separate them. Birth dates come from Wikidata (property P569), which is CC0. Members whose birth date is not recorded there are not in the count at all: we hold 1581 member places across 263 groups, and 1303 people survived after removing duplicates and the 1 January artefact.