Prostate volume calculator
from three numbers on your report
Ultrasound and MRI reports often list the prostate's length, width, and height without the volume, or bury the volume in a line nobody explains. Enter the three dimensions here and the calculator applies the same ellipsoid formula the imaging software uses, then tells you what the size means. Add your PSA and it calculates your PSA density too.
Medically reviewed by Hari Sawkar, MD, board-certified urologist · Updated October 2026
The calculator
Enter the three dimensions in any order. Most reports list them in centimeters; if yours shows millimeters (numbers like 45 × 40 × 35), switch the units.
The result is an estimate. Imaging software rounds the same way, and two scans of the same gland routinely differ by a few cc. Nothing here replaces an evaluation.
How the formula works
Imaging treats the prostate as an ellipsoid, a slightly flattened egg, and measures it along three axes. Volume is the product of the three, times a constant:
Volume (cc) = length × width × height × 0.52
The 0.52 is π divided by 6, rounded. Some software uses 0.523 or 0.5236; the difference is a fraction of a cc. Because the gland is not a perfect ellipsoid, the formula is a close estimate rather than an exact measurement.
A worked example: a report reading 4.5 × 4.0 × 3.5 cm gives 4.5 × 4.0 × 3.5 × 0.52 = 32.8, so about 33 cc, mild enlargement.
| Dimension | Also called on reports | Direction |
|---|---|---|
| Length | Craniocaudal, sagittal, longitudinal | Top to bottom, from the bladder toward the base of the penis |
| Width | Transverse | Side to side; usually the largest of the three |
| Height | Anteroposterior (AP) | Front to back |
The order does not change the answer; multiplication works the same either way. Transrectal ultrasound and MRI measure more precisely than ultrasound through the belly.
What your volume means
cc and grams are interchangeable here, because prostate tissue weighs almost exactly what water does. Size decides which treatments fit; symptoms decide whether to treat at all.
| Volume | Everyday size | Treatments that fit, if symptoms warrant |
|---|---|---|
| Under 25 cc | A walnut | The typical baseline; symptoms at this size are usually not about volume |
| 25–40 cc | A golf ball to an apricot | Medication, UroLift, or Rezūm; watchful waiting is often fine |
| 40–80 cc | A lemon | The full menu: UroLift, Rezūm, PAE, and Aquablation |
| 80–150 cc | An orange | PAE and Aquablation; HoLEP for some anatomies |
| 150+ cc | A grapefruit | PAE has no practical size ceiling; HoLEP when surgery is needed |
Normal volume by age, what size is dangerous, and why shape matters as much as size are all on the prostate size chart. To see how much your symptoms cost you, take the two-minute IPSS score.
PSA density: why volume changes what PSA means
PSA comes from all prostate tissue, benign or not, so a large gland can produce an elevated PSA with no cancer anywhere. Dividing PSA by volume, a figure called PSA density, adjusts for that. A PSA of 6 means something different in a 30 cc prostate (density 0.20) than in a 90 cc prostate (density 0.07).
Many urologists use 0.15 ng/mL per cc as the level above which a closer look, usually an MRI, is considered. Density is one input alongside your exam, your PSA trend over time, and imaging; it is not a diagnosis. Typical PSA values by age are on the PSA levels by age chart.
Common questions about prostate volume
What is the formula for prostate volume
Length times width times height times 0.52. It is the formula for the volume of an ellipsoid, and 0.52 is pi divided by 6, rounded. Ultrasound machines and MRI software use the same formula, so entering the three dimensions from your report reproduces the volume they would print.
Is prostate volume in cc the same as grams
For practical purposes, yes. Prostate tissue is almost exactly the density of water, so a 60 cc prostate weighs about 60 grams. Ultrasound and MRI reports usually say cc or mL; pathology reports say grams.
What is a normal prostate volume
About 20 to 30 cc for a healthy adult, roughly walnut-sized. Reports often call anything over 30 cc enlarged and over 40 cc clearly enlarged, but those are conventions. A 45 cc prostate at 70 is ordinary; whether it blocks flow is the real question.
Why do my ultrasound and MRI give different volumes
The gland is not a perfect ellipsoid, and each scan measures its edges slightly differently, so two scans of the same prostate routinely differ by a few cc. Ultrasound through the belly is the least precise; transrectal ultrasound and MRI measure more closely. A small difference does not change the treatment conversation.
How do I calculate PSA density
Divide your PSA in ng/mL by your prostate volume in cc. A PSA of 6 with a 60 cc prostate gives a density of 0.10. Many urologists use 0.15 as the level above which a closer look, usually an MRI, is considered. Density is one input alongside your exam, PSA trend, and MRI, not a diagnosis.
Turn your number into a plan
Bring your report, or get measured with a quick in-office ultrasound at the consultation. Same-day and next-day appointments for urgent concerns, telehealth available, Medicare and most PPO plans accepted.
Chief of Urology, Providence St. Joseph Hospital · UroLift Center of Excellence · 250+ Aquablation procedures