Vaginas vary significantly in size and shape from person to person, and they also change in dimensions throughout an individual's life based on factors like arousal, hormonal cycles, and age. 

Average Dimensions (Resting State)
When a woman is in a relaxed, unaroused state, the vagina is a muscular tube with collapsed walls that vary in length. 

Depth: Research estimates the average depth is between 3 and 4 inches (7–10 cm). Some studies show a broader range of 2 to 5 inches.

Width: The vaginal canal is typically narrower near the opening (introitus) and wider toward the cervix. Average widths range from about 0.6 inches (1.7 cm) at the opening to 1.8 inches (4.5 cm) at the widest point near the cervix. 

Factors That Cause Size Variations
The vagina is highly elastic and changes its dimensions to accommodate specific functions. 

Sexual Arousal: During arousal, the vagina undergoes "tenting." Blood flow increases, the cervix lifts, and the vaginal walls expand, often doubling in depth to 4–8 inches to accommodate penetration.

Menstrual Cycle: The position of the cervix changes throughout the month. During menstruation, it typically sits lower, making the vaginal canal feel shorter.

Childbirth: The vagina stretches significantly during delivery to allow a baby to pass. While it generally returns to its original size afterward, some permanent changes in width or elasticity may occur.

Aging & Menopause: As estrogen levels drop during menopause, vaginal tissues may become thinner, drier, and less elastic, which can lead to a slight shortening or narrowing of the canal (vaginal atrophy).

Genetics: Like any other body part, the baseline size and shape of a woman's internal and external genitalia are largely determined by genetics. 

External Variation (The Vulva)
People often use the word "vagina" to refer to the entire area, but the visible external part is the vulva, which also varies widely in size and appearance. 

Labia Majora (Outer Lips): Can range from 2.7 to 4.7 inches (7–12 cm) in length.

Labia Minora (Inner Lips): Can be very small and hidden by the outer lips or long and protruding (up to an inch or more beyond the outer lips).

Asymmetry: It is extremely common and normal for one side of the labia to be larger or a different shape than the other.