The length of the vagina varies among women of child-bearing age. Because of the presence of the cervix in the front wall of the vagina, there is a difference in length between the front wall, approximately 7.5 cm (2.5 to 3 in) long, and the back wall, approximately 9 cm (3.5 in) long.[10][24] During sexual arousal, the vagina expands both in length and width.

https://en.wikipedia.org/wiki/Vagina?wprov=sfla1

Somewhat nsfw link