The ovaries are two small, almond-shaped organs located in the pelvis on either side of the uterus. Their primary function is producing the female reproductive cells, or eggs, and manufacturing the hormones estrogen and progesterone, which regulate the menstrual cycle and support pregnancy. Measuring ovarian dimensions is a routine diagnostic tool because the size and appearance of these organs are closely linked to their functional state. Understanding what constitutes a “normal” ovarian size is complex because this measurement is not static; it changes significantly throughout a person’s life and fluctuates over the course of a single month.
Standard Normal Dimensions During Reproductive Years
For an adult woman in her reproductive years, the ovaries maintain a relatively consistent average size, typically assessed using transvaginal ultrasound. These measurements are three-dimensional, capturing the organ’s length, width, and thickness. The typical length of a healthy ovary ranges from 3 to 5 centimeters (cm), similar to the size of a small plum.
The average width generally falls between 1.5 and 3 cm, while the thickness is usually between 0.6 and 1.5 cm. These linear measurements are used to calculate the ovarian volume, which provides a single, standardized number for comparison.
The mean ovarian volume for a premenopausal adult is generally between 6 and 7 cubic centimeters (cc). A healthy range typically falls between 3 and 10 cc. It is common for the right and left ovaries to show a slight difference in size, and this asymmetry is not a cause for concern. The upper limit of normal volume for a premenopausal ovary is generally considered to be 20 cm³.
Physiological Changes: Ovarian Size During the Menstrual Cycle
Ovarian size is not fixed, but undergoes predictable, temporary changes driven by the monthly fluctuation of reproductive hormones. This physiological variation means that an ovary measured at the beginning of the cycle will look different than one measured mid-cycle or near the end. The cyclical changes are primarily confined to the dominant ovary, which is the one preparing to release an egg that month.
During the follicular phase, several follicles begin to develop, but only the dominant follicle continues to mature. This growing fluid-filled sac causes a measurable increase in the overall volume of that ovary. By the time of ovulation, the dominant follicle can swell to a diameter of 18.5 to 24 millimeters (mm), representing a substantial, temporary enlargement.
Once the egg is released during ovulation, the follicle ruptures, and the ovarian volume may briefly decrease. The remaining follicular tissue transforms into the corpus luteum, marking the start of the luteal phase. The corpus luteum is highly active, causing the ovary’s size to increase again, sometimes nearly matching its pre-ovulatory volume.
The corpus luteum produces high levels of progesterone, which prepares the uterus for a potential pregnancy. If pregnancy does not occur, the corpus luteum begins to break down, and the ovary’s volume returns to its baseline size before the next cycle begins. Any single measurement of ovarian size must be interpreted within the context of her menstrual cycle phase.
Ovarian Size Progression Across the Lifespan
The size of the ovaries changes dramatically across a woman’s life, reflecting the current state of her reproductive endocrine system. In childhood and before the onset of puberty, the ovaries are small and relatively inactive. A newborn’s ovary measures about 1 centimeter in diameter, and the mean volume for a young child is less than 2 mL.
Ovarian volume begins to steadily increase around the age of 10, accelerating with the hormonal changes of puberty. The ovaries reach their maximum average volume around age 20, with a mean volume of approximately 7.7 mL. After this peak, the volume begins a gradual decline with each passing decade, reflecting the natural reduction in the ovarian reserve.
The most notable long-term change occurs after menopause, when the follicular reserve has been depleted and the production of reproductive hormones significantly decreases. This lack of hormonal stimulation causes the ovaries to undergo atrophy, or shrinkage. Post-menopausal ovaries are substantially smaller than those in the reproductive years, with a mean volume of about 2.2 mL. For post-menopausal women, an upper limit of normal volume is often set at 10 cm³, and any volume exceeding this threshold warrants further investigation.