According to a study published in the British Journal of Obstretrics & Gynaecology, the average depth of a vagina is 3.77 inches or 9.6cm. That compares with the average penis size of 5.2 inches in length and 4.6 inches in circumference, erect.
However similar to male genitalia, when aroused, the vagina can expand to between 4.25 inches and 4.75 inches. According to Go Ask Alice at Columbia University, during arousal, blood flows to the genital area, and sexual excitement causes the cervix and uterus to ascend as the upper two-thirds of the vagina lengthen.
When something is placed inside, the walls can expand and mould around the width to accommodate the size of a penis, toy, finger(s) or tampon.
During birth, the size of the vagina will briefly change before returning to normal. To accommodate the size of the baby, the woman's cervix, vaginal canal and vulva all dilate to about 10 centimetres in diamatre, says website Splinter.
If between her legs is unfamiliar territory for you, here are 16 new ways to touch her vagina.