Member ages
I.O.I Member Ages and Birthdays
I.O.I member ages and birthdays ranked oldest to youngest, from Nayoung at age 30 to Somi at age 25.
Average27.2years old
Oldest to youngest
| Rank | Member | Age | Birthday | Position |
|---|---|---|---|---|
| #1 | NayoungFormer member | 30 | Dec 18, 1995 | Leader, Main Rapper, Lead Dancer, Vocalist |
| #2 |  ChunghaFormer member | 30 | Feb 9, 1996 | Main Dancer, Lead Vocalist, Rapper |
| #3 |  SejeongFormer member | 29 | Aug 28, 1996 | Main Vocalist |
| #4 |  ChaeyeonFormer member | 28 | Dec 1, 1997 | Vocalist, Visual |
| #5 |  KyulkyungFormer member | 27 | Dec 16, 1998 | Lead Dancer, Vocalist, Visual |
| #6 |  SohyeFormer member | 26 | Jul 19, 1999 | Vocalist, Rapper |
| #7 |  YeonjungFormer member | 26 | Aug 3, 1999 | Main Vocalist |
| #8 |  YoojungFormer member | 26 | Nov 12, 1999 | Lead Rapper, Lead Dancer, Lead Vocalist |
| #9 |  DoyeonFormer member | 26 | Dec 4, 1999 | Vocalist, Visual |
| #10 |  MinaFormer member | 26 | Dec 4, 1999 | Lead Dancer, Vocalist, Rapper |
| #11 | SomiFormer member | 25 | Mar 9, 2001 | Lead Dancer, Lead Vocalist, Rapper, Face of the Group, Center, Maknae |