About

Prostate volume is a fundamental parameter in evaluating lower urinary tract symptoms (LUTS) in men. Whether measured via Transrectal Ultrasound (TRUS) or MRI, the volume helps distinguish between Benign Prostatic Hyperplasia (BPH) and other conditions. It is also the denominator in the critical equation for Prostate Specific Antigen Density (PSAD).

PSAD is calculated as PSA / Volume. This metric improves the specificity of PSA testing. A large prostate often produces more PSA naturally (BPH), whereas a small prostate with high PSA is more suspicious for malignancy. This tool calculates both the volume using the standard ellipsoid formula and the density index, providing immediate risk stratification context.

Formulas

1. Prostate Volume (Ellipsoid Formula):

Vol = L × W × H × 0.52

2. PSA Density (PSAD):

PSAD = Serum PSA (ng/mL)Vol (cc)

Reference Data

Parameter	Value Range	Interpretation / Risk Profile
Normal Volume	20 - 30 cc	Healthy adult male prostate size.
Mild Enlargement	30 - 50 cc	Likely early BPH. Monitor symptoms.
Moderate Enlargement	50 - 80 cc	Significant BPH. Medical therapy often indicated.
Severe Enlargement	> 80 cc	Candidates for surgical intervention (e.g., TURP, HoLEP).
Normal PSA Density	< 0.10	PSA elevation likely due to BPH volume.
Suspicious Density	0.10 - 0.15	Grey zone. Clinical correlation required.
High Risk Density	> 0.15	High suspicion of cancer. Biopsy strongly considered.

Frequently Asked Questions

While 0.523 (pi/6) is mathematically precise for an ellipsoid, the urological convention simplifies this to 0.52. This is the standard multiplier programmed into most ultrasound machines and found in major clinical guidelines (AUA/EAU).

PSA is organ-specific, not cancer-specific. BPH tissue produces PSA. By dividing PSA by volume, we normalize the value. If the density is high (>0.15), it means the prostate is producing "too much" PSA for its size, which suggests cancer cells (which leak more PSA) rather than just benign enlargement.

Yes. MRI is often more accurate than TRUS for dimensions. The same ellipsoid formula applies. Note that some radiologists may use "bullet" or "pear" shape formulas, but ellipsoid remains the standard for general clinical PSAD calculation.

Input them as Centimeters (e.g., 40mm = 4.0cm). The calculator includes a safety check: if you enter values > 20, it assumes you accidentally entered millimeters and will prompt a warning to ensure accuracy.