Prostate Volume Calculator
Estimate prostate volume from three measurements — plus gland weight and PSA density.
Three measurements
Enter the length, width, and height in centimetres from a transrectal ultrasound or MRI report.
An estimate, not a diagnosis
Volume is one input a clinician uses alongside symptoms, exam, and PSA — it is not a diagnosis on its own.
What is prostate volume?
Why the size of the gland matters
Prostate volume is the size of the prostate gland, expressed in millilitres (equivalent to cubic centimetres). It is estimated from three diameters measured on imaging and is a routine number in urology. As clinical references such as StatPearls (NIH) and the European Association of Urology describe, gland size helps explain urinary symptoms, guides treatment choices for benign prostatic hyperplasia (BPH), and — combined with a PSA blood test — sharpens cancer risk assessment through the PSA density.
The prostate is modelled as a prolate ellipsoid — an egg shape — so its volume is the product of the three diameters and a constant.
volume = (π / 6) × length × width × height ≈ 0.52 × L × W × HThe factor π/6 is about 0.52, which is why the ellipsoid method is often written as the "0.52 formula". Multiplying the volume by roughly 1.05 — the density of prostate tissue — gives the estimated gland weight in grams, so a 33 mL prostate weighs about 35 g. If you also enter a PSA value, dividing it by the volume gives the PSA density, a number that helps put a borderline PSA into context.
An MRI report lists the prostate as 4.5 cm long, 4.0 cm wide, and 3.5 cm in depth, with a recent PSA of 4.0 ng/mL.
Multiply the three diameters
4.5 × 4.0 × 3.5 = 63 cm³ before the shape factor.Apply the ellipsoid factor
63 × 0.52 ≈ 33 mL — the prostate volume.Estimate the weight
33 × 1.05 ≈ 35 g.Work out PSA density
4.0 ÷ 33 ≈ 0.12 ng/mL/cm³ — below the commonly cited 0.15 threshold.
Volume and PSA density are interpreted against rough reference points, but only a clinician can apply them to your situation.
Around 20–30 mL
A typical adult prostate. Size tends to rise gradually with age, so a single number means little without context.
Above ~30 mL
Often described as enlarged and may be associated with BPH, especially when urinary symptoms are present.
PSA density over 0.15
A higher PSA density is one factor that may prompt a urologist to consider further testing such as biopsy.
PSA density exists because a high PSA can simply reflect a large gland rather than cancer. Dividing PSA by volume separates those cases: the same PSA of 4.0 ng/mL means something different in a 25 mL gland than in a 60 mL gland. The often-quoted 0.15 ng/mL/cm³ cut-off is a guide, not a rule — guidelines from bodies like the American Urological Association treat it as one piece of a larger picture.
The volume is your estimated gland size, the weight is that volume scaled by tissue density, and the PSA density (when you provide a PSA) relates your blood test to the gland size. None of these is a diagnosis. Volume naturally increases with age, individual glands vary in shape, and the same measurements can accompany very different clinical pictures depending on symptoms, examination, and history. Use the result to understand your imaging report and to ask better questions, not to reach a conclusion on your own.
The arithmetic is exact; the clinical meaning is not.
For information only — consult a healthcare professional
This calculator is for general information and education only and is not a medical diagnosis. The ellipsoid formula is an approximation — measurement technique, gland shape, and the presence of a median lobe all affect accuracy, and imaging-based volumes can differ by 10–20 % from the true value. Reference ranges and the PSA-density threshold are general guides that vary between guidelines and individuals. Always discuss your measurements, PSA, and any symptoms with a urologist or other qualified healthcare professional before making any decision about testing or treatment.