Ovary size and volume is frequently determined with ultrasound. The volume estimate is calculated by the formula for an ellipsoid, where D1, D2, and D3 are the three axial measurements:
D1 x D2 x D3 x 0.52
The normal, adult, non-pregnant, mean ovary volume of women who are not postmenopausal is 6-7 mL based on several studies which combined assessed tens of thousands of ovaries.
20 mL had been proposed as a cut-off value between normal and abnormally large, but that value was subsequently shown to be inaccurate. Values two standard deviations above the mean (to help provide a threshold for enlargement):
- 14-15 mL at <30 years of age
- 13 mL in the 30s
- 11 mL in the 40s
- 5-6 mL in the 50s
- 4-5 mL above 60 years of age
Ovary volume varies normally a bit by overall body size/height. Normal ovary volume during the fertile years may be as high as 24 mL and perhaps even higher. The two ovaries may vary greatly in volume, side to side; it is not uncommon for one ovary to be twice the volume of the other.
There was no significant difference in ovary volume between studies done on a mixed U.S. population versus a cohort in Nigeria.