How deep is the vagina from the opening to the cervix opening? just the average.

3-4 inches: The average vagina is 3-4 inches long. The vagina can expand by 200% when sexually aroused, kind of like a balloon.

Vaginal length: The average length of the unaroused vagina is 3-4 inches. During arousal, however, it elongates to more than twice that size, thus allowing for comfortable penetration during intercourse.

Length of index: finger. In a normal sized person, the cervix can be felt by the index finger of a person with a normal sized hand. Please note that vagina is quit stretchable as most penises are larger than the index finger and do not cause discomfort.