Prostate Volume Calculator

Written by Great Medico

Updated September 27, 2026 •2 min read

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Prostate size is often estimated from three imaging measurements rather than measured directly. The Prostate Volume Calculator converts length, width, and height into an estimated gland volume using the standard ellipsoid model, the alternative bullet model, or both side by side. You can also enter a PSA value to calculate PSA density.

What this calculator does

Choose Ellipsoid, Bullet, or Compare both. Enter prostate length, width, and height using centimeters, meters, inches, or feet; the calculator normalizes the dimensions internally. If PSA is available, enter it in ng/mL to add a PSA-density result based on the selected volume estimate.

How to use the Prostate Volume Calculator

Use dimensions measured from the same imaging study and follow the measurement orientation provided by the radiology or ultrasound report. For the most direct workflow, enter dimensions in centimeters. Review the selected geometric model before interpreting the volume, because different models can produce meaningfully different estimates for the same three measurements.

Prostate volume formulas

The ellipsoid model uses V = L × W × H × π/6, equivalent to multiplying the three dimensions by about 0.524. The bullet model uses V = L × W × H × 5π/24, a factor of about 0.6545. With measurements in centimeters, the result is in cubic centimeters (cc), numerically equivalent to milliliters (mL). The compare mode shows both estimates.

PSA density

When PSA is entered, the calculator uses PSA density = PSA ÷ prostate volume. PSA density can provide additional context because the same PSA value may be interpreted differently in a smaller versus larger gland. It is still only one clinical measurement and should not be used by itself to diagnose or exclude prostate cancer or benign prostatic hyperplasia.

Worked example

For dimensions of 4 cm × 4 cm × 3 cm, the ellipsoid estimate is 8π ≈ 25.13 mL. The bullet estimate is 10π ≈ 31.42 mL, which is 25% larger for the same dimensions because of the different geometric coefficient. If PSA were 4 ng/mL, the ellipsoid-based PSA density would be about 0.159 ng/mL².

How to interpret the result

This is a geometric estimate of gland volume, not a diagnosis. Prostate measurements can vary with imaging modality, scan plane, gland contour, and observer technique. Volume and PSA density are interpreted alongside age, symptoms, examination, PSA trend, imaging findings, medications, and other clinical information.

Medical limitations and safety

Do not use this calculator to decide whether cancer is present or absent, whether a biopsy is needed, or whether treatment should start or stop. Imaging-derived prostate volume can differ between ultrasound, MRI, CT, and contour-based methods. Review medically important results with a qualified clinician, especially when the calculation is being used to interpret an abnormal or changing PSA result.