It is a very curious question you asked. One thing I clearly at first that only in rare cases a penis can not insert in the vagina completely. A man’s penis can go up to three to six inches long on average. Vagina gets wider as the man’s penis move from the vaginal opening towards the cervix. The vagina can change its shape and size up to 200 percent in certain conditions like in sex and childbirth.
You may surprise to know that a girl with a tall body or petite body is not related to vaginal length. It is not necessary that a small girl can have a small vagina in length or a tall girl have a large vagina in length.
Vaginal length:
Vaginal length can vary significantly in certain conditions. The back wall which is closer to the rectum is longer and can range from 5.1 to 14.4 cm, and the front wall ranges from 4.4 to 8.4 cm. (source)
The vagina can expand up to 200 percent when sexually aroused like a balloon. You are a wonder to think why is it so expandable? It is very elastic because the vagina is made to the birth child. It is like an empty balloon if neither penis nor babies in a woman’s vagina.
Changes of vagina size while aroused and having sex:
A vagina changes their sizes and can get longer when sexually aroused. Sexual arousal forces woman’s cervix and uterus to lift up and out of the way, which causes the upper two-thirds of woman’s vagina to lengthen.
Blood flow increased to the vagina while a woman aroused and this causes the vagina to elongate and the cervix, or tip of the uterus, to lift up slightly, allowing more of a penis, finger, or sex toy to fit in the vagina. When the vagina is aroused, it elongates, lubricates, and expands.
Some women might feel hitting penis into their vagina is because they are not turned on enough to allow their vagina for full penetration.
Vagina changes in certain condition:
| Certain Situation | Length | Diameter |
| When vagina relaxed | 3.5 to 4 inches | <1 inch |
| When vagina aroused | 5 to 6 inches | 1.5 to 2.5 inches |
| When vagina stretched | 8 to 9 inches | 2.5 to 3 inches |
Penis isn’t too long for the vagina?
Usually, the penis isn’t too long for the vagina, if a man not able to insert the penis in the vagina. This is because vagina is not aroused and in relaxed condition. A vagina have to prepare before inserting penis into it. As you see the above table that vagina length is not fixed and can change in different conditions.
Can a penis be too big to fit in vagina?
It is generally not happened and can be happened in a very rare situation. Most penis sizes easily fit in the vagina and if not fitted, there may be the reason for penis size which is above 9 inches or more. But the average penis size is 5.16 inches.
Reason behind the expandable length of the vagina:
At the age of 20s, 30s and 40s, the estrogen level of woman is naturally very high which helps to keep woman vaginal tissue supple and this is also responsible for expandable of vagina and less sensitive during this age.
But after the age of 40s when menopause arrived in a woman’s body, the production level of estrogen in a woman’s body gets decreased and the vagina becomes more sensitive. During this age of time woman feel very difficulty in inserting the penis because the vagina produces less lubricant. Both a larger and an average penis faced difficulty in inserting the penis and this causes pain in both women and men.
