Ovarian Volume Calculator: Ovary Size From Ultrasound Measurements
Ovarian volume is calculated with the prolate ellipsoid formula: 0.523 × length × width × height, with all three measurements taken in centimetres in perpendicular planes. The result, in millilitres, is the standard way ovary size is reported on a pelvic or transvaginal ultrasound.
The formula and how it is measured
The sonographer records the ovary in the longitudinal plane for length and anteroposterior depth, then rotates 90 degrees for width. Multiplying the three and applying π/6 (0.523) approximates the ovary as a smooth ellipsoid. A 3.0 × 2.0 × 1.5 cm ovary therefore measures 4.71 mL. Because the calculation multiplies three lengths, measurement error compounds — which is why volumes near a reference boundary are treated cautiously.
Commonly quoted reference ranges
- Pre-pubertal: usually under about 3 mL.
- Reproductive age: commonly about 3–10 mL, varying across the menstrual cycle as follicles develop.
- Postmenopausal: usually under about 8 mL, decreasing with years since menopause.
- Polycystic ovary morphology criteria use a volume threshold of about 10 mL alongside follicle counts.
Why volume changes through the cycle
A dominant follicle can reach 2 cm before ovulation and a corpus luteum persists afterwards, so the same healthy ovary can measure noticeably different volumes in the same month. Follow-up scans are often scheduled in the early follicular phase, days 3 to 5, precisely so measurements are comparable.
What volume alone cannot tell you
Volume is one descriptor among many. A raised figure may reflect a physiological cyst, a dominant follicle, polycystic morphology or a mass, and only the full report — echotexture, follicle count, Doppler findings and symptoms — distinguishes between them. Equally, a normal volume does not exclude disease. Use the number to understand your report, then discuss it with the clinician who ordered the scan.
Key takeaways — Ovarian Volume Calculator
- Ovarian volume = 0.523 × L × W × H in centimetres, reported in millilitres.
- Roughly 3–10 mL is typical in reproductive years; under about 8 mL after menopause.
- Cycle phase changes ovarian volume, so compare scans taken at the same point in the cycle.