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Prostate Volume Calculator

Source: Rodriguez E Jr, et al. Prostate volume estimation using the ellipsoid formula consistently underestimates actual gland size. J Urol. 2008;179(2):501-503 · Source verified July 22, 2026

Blake Boege
Written by Blake Boege · Founder, Calculator Answers

A prostate volume calculator estimates the volume of the prostate gland using measurements obtained from ultrasound or MRI scans, applying the ellipsoid formula (volume = width × height × length × 0.5236). It is commonly used in urology to assess benign prostatic hyperplasia (BPH) and to calculate PSA density (PSA level divided by volume), which helps assess the risk of prostate cancer.

Estimate prostate volume using the ellipsoid formula from ultrasound measurements, compute tissue weight, and analyze PSA density.

See also: Pyramid Volume Calculator, Volume Calculator – Rectangular Prism, Cylinder, Sphere & Cone, and Volume Converter.

Quick Answer

Estimate your prostate volume and weight from ultrasound measurements (width, height, length) using the ellipsoid formula. Also calculates PSA density if a PSA level is provided.

Typically the largest side-to-side measurement.
Typically the front-to-back measurement.
Typically the top-to-bottom measurement.
Used to calculate PSA density (prostate-specific antigen relative to volume).
Prostate Volume & Weight

Estimated Volume

31.4 cc

Weight: ~33 grams (g)

Ellipsoid Volume31.4 cc (or mL)
Estimated Weight33 g

Provide an optional PSA level to see PSA density analysis.

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How it works

Formula · Volume = length × height × width × π/6 (0.52), the prolate ellipsoid formula

How does the prostate volume calculation work?

Prostate volume is calculated using the dimensions obtained from diagnostic imaging, usually a transrectal ultrasound (TRUS) or pelvic MRI. The measurements required are:

  • Width (Transverse diameter): The widest horizontal span of the prostate.
  • Height (Anteroposterior diameter): The vertical distance from front to back.
  • Length (Sagittal diameter): The length from base to apex (top to bottom).

The Ellipsoid Volume Formula

Because the prostate resembles a flattened sphere or ellipse, its volume is calculated using the standard mathematical formula for the volume of an ellipsoid:

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

Since the dimensions are input in centimeters (cm), the resulting volume is in cubic centimeters (cc), which is equivalent to milliliters (mL).

What is PSA Density?

Prostate-Specific Antigen (PSA) is a protein produced by both normal and cancerous prostate cells. An elevated PSA level can indicate prostate cancer, but it is also commonly elevated due to Benign Prostatic Hyperplasia (BPH) or inflammation (prostatitis).

To help determine if a high PSA is due to a large but benign prostate or a smaller prostate with a high risk of cancer, clinicians calculate PSA Density (PSAD):

PSA Density = PSA Level (ng/mL) / Prostate Volume (cc)

If the PSA density is higher than 0.15 ng/mL/cc, it indicates that the prostate is producing more PSA than would be expected for its size alone, raising the suspicion of prostate cancer.

Medical Disclaimer

This calculator provides volume and PSA density estimates for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. All clinical decisions, diagnostic determinations, and treatment plans must be made by qualified healthcare providers (such as a urologist) in the context of a complete medical evaluation.

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Frequently asked questions

Less than its ubiquity suggests, and the paper this page cites as its source is the one saying so. Rodriguez and colleagues, whose title is literally that the ellipsoid formula consistently underestimates actual gland size, report that even with dimensions measured on the specimen rather than by ultrasound the formula "accurately (+/-10%) predicted weight in 26.5% of the cases vs 13.3% by ultrasound", and that "the primary underlying factor for inconsistency with volume estimation of prostate weight appears to be the ellipsoid formula since pathologically determined dimensions still had a 75% error". So roughly three quarters of estimates fall outside 10 percent of the true weight, and the error runs in one direction. A later study reported 0.66 as a better-fitting coefficient than the ellipsoid's 0.52. This page keeps 0.52 because it is what urology reports and PSA density calculations actually use, so it is the number that matches your radiology report, but treat the result as a systematic underestimate rather than a measurement.

Prostate volume is most commonly estimated using transrectal ultrasound (TRUS) or MRI. Radiologists measure three dimensions of the prostate (width, height, and length) and apply the ellipsoid formula: Volume = Width × Height × Length × 0.5236. This assumes the prostate is shaped like a three-dimensional ellipse (an ellipsoid).

Knowing the prostate's size is essential for diagnosing and managing Benign Prostatic Hyperplasia (BPH) and evaluating the significance of PSA (Prostate-Specific Antigen) levels. A larger prostate naturally produces more PSA. Estimating volume helps differentiate between benign enlargement and potential malignancy via PSA density.

The walnut comparison is standard and verifies; the number this page used to give did not. StatPearls puts a normal prostate at 20 to 30 cc, and Berry and colleagues' 1984 autopsy series, which is the source for the young-adult figure specifically, reports that "the normal prostate reaches 20 plus or minus 6 gm. in men between 21 and 30 years old". The 20 to 25 cc this page previously stated is narrower than either and was not found in any source consulted. The prostate naturally enlarges as men age. In older individuals, a volume of 30 to 80 cc or more is common and is associated with Benign Prostatic Hyperplasia (BPH).

PSA density is calculated by dividing the serum PSA level (ng/mL) by the prostate volume (cc or mL). For example, if a patient has a PSA of 4.0 ng/mL and a prostate volume of 40 cc, the PSA density is 0.10 ng/mL/cc. It is a metric used to assess the likelihood of prostate cancer.

0.15 is real and widely used: StatPearls describes it as the international consensus figure for an abnormal PSA density, while noting that higher cut-offs of 0.18, 0.20 and even 0.30 have been proposed. But read it as one input rather than a verdict. The 2026 AUA/SUO early detection guideline says risk across PSA density is continuous and "cautions against use of threshold values in isolation for management decision-making", and a 2023 Eur Urol Focus analysis of 8,974 biopsies found "no discontinuity in the risk of high-grade prostate cancer at a PSAd cutoff of 0.15" and recommended at least 0.20 in the MRI era. A value at or below 0.15 does not rule anything out.

Prostate tissue has a density of approximately 1.05 grams per milliliter (g/mL). Therefore, the weight of the prostate in grams is very close to its volume in cubic centimeters (V × 1.05). For clinical purposes, radiologists and urologists often use cc and grams interchangeably.