We hold member records for 263 groups — 1,588 people in all. Counting them gives a plain answer about size, and a less obvious one about age.
5 members is the most common size (52 groups), the median is 6, and 79% of all groups have between three and seven.
The less obvious part: the bigger the group, the wider the age gap between its oldest and youngest member — and it does not reverse once across the size bands. Median gap goes from 3 years at the smallest size to 13 years at the largest.
A thirteen-member line-up is not five members plus eight. It reaches across a different span of birth years, and that is a different thing to assemble.
Age gap is the distance between the oldest and the youngest member's birth year. Groups whose birth years we do not hold are counted in the first column but left out of the gap figures — the "measured" column says how many were usable.
| Members | Groups | Measured | Median age gap | Widest in band |
|---|---|---|---|---|
| 3 | 40 | 39 | 3 yrs | 10 yrs |
| 4 | 39 | 39 | 4 yrs | 10 yrs |
| 5 | 52 | 52 | 4 yrs | 12 yrs |
| 6 | 39 | 39 | 5 yrs | 29 yrs |
| 7 | 38 | 38 | 5 yrs | 9 yrs |
| 8–9 | 33 | 33 | 5 yrs | 13 yrs |
| 10–13 | 20 | 20 | 7 yrs | 14 yrs |
| 14+ | 2 | 2 | 13 yrs | 13 yrs |
| Members | Groups | Share |
|---|---|---|
| 3 | 40 | 15% |
| 4 | 39 | 15% |
| 5 | 52 | 20% |
| 6 | 39 | 15% |
| 7 | 38 | 14% |
| 8 | 18 | 7% |
| 9 | 15 | 6% |
| 10 | 7 | 3% |
| 11 | 5 | 2% |
| 12 | 6 | 2% |
| 13 | 2 | 1% |
| 24 | 1 | 0% |
| 26 | 1 | 0% |
Oldest and youngest birth year on record, with the gap between them.
| Group | Members | Oldest born | Youngest born | Gap |
|---|---|---|---|---|
| Metafive | 6 | 1952 | 1981 | 29 yrs |
| After School | 11 | 1980 | 1994 | 14 yrs |
| NCT | 26 | 1994 | 2007 | 13 yrs |
| Secret Number | 9 | 1995 | 2008 | 13 yrs |
| Pink Fantasy | 8 | 1993 | 2005 | 12 yrs |
| god | 5 | 1969 | 1981 | 12 yrs |
| Stray Kids | 10 | 1990 | 2001 | 11 yrs |
| Saja Boys | 5 | 1980 | 1991 | 11 yrs |
| Wanna One | 11 | 1991 | 2001 | 10 yrs |
| X1 | 11 | 1994 | 2004 | 10 yrs |
Of 1,588 members, we have a birth date for 1,516(95%) and a birthplace for 1,324(83%). The rest are counted as members but left out of any figure that needs those fields. They are not treated as zero.
Line-ups change. This is who the record lists, not who stood on stage at debut. A group that added or lost members shows the full roster, which is one reason the largest counts are as large as they are.
We do not say which size is better. Size is a count; better is a judgement, and not ours to make. The tables are here so the question can be asked with numbers instead of impressions.