Prostate Volume & PSAD Calculator

Understanding Prostate Volume & Clinical Relevance

Accurate volumetric assessment of the prostate gland guides surgical planning (such as TURP, HoLEP, or robotic prostatectomy), medication selection (5-alpha reductase inhibitors like finasteride), and biopsy risk stratification.

Standard Ellipsoid Formulation

The human prostate approximates a prolate ellipsoid. The volume V is computed as:

V = (π / 6) × Length × Width × Height ≈ 0.5236 × Length × Width × Height

Where:

• Length: Craniocaudal length (cm)
• Width: Transverse width (cm)
• Height: Anteroposterior height (cm)
• Result is expressed in cubic centimeters (cc) or milliliters (mL), where 1 cc = 1 mL.

Prostate volume & PSAD – calculation example

Let’s see an example clinical calculation:

1. Enter the length: length = 4.2 cm.
2. Enter the width: width = 4.8 cm.
3. Enter the height: height = 3.6 cm.
4. Enter total serum PSA: PSA = 5.2 ng/mL.
5. The calculation results are available for you: volume = 38.0 cc and PSA Density = 0.137 ng/mL/cc.

💡 A PSA density below 0.15 ng/mL/cc is generally reassuring, suggesting benign enlargement rather than aggressive malignancy.

Bullet Formula Alternative

Some urologists use the “bullet formula” (V = 0.48 × Length × Width × Height) or an adjusted cylinder coefficient (0.58) for elongated or asymmetrically lobed glands, but 0.52 remains the gold-standard recommendation by the American Urological Association (AUA).

Prostate-Specific Antigen Density (PSAD)

PSAD = Total PSA (ng/mL) / Prostate Volume (cc)

• PSAD < 0.10 ng/mL/cc: Lower suspicion of malignancy; PSA elevation is predominantly driven by benign enlargement.
• PSAD 0.10 – 0.15 ng/mL/cc: Intermediate / borderline zone.
• PSAD > 0.15 ng/mL/cc: Heightened suspicion for prostate cancer; further diagnostic evaluation is clinically indicated.

Disclaimer: This tool provides educational mathematical computations and is not a substitute for professional clinical judgment.