PSA Density Calculator
Calculate PSA density by dividing total PSA by prostate volume — a refinement that helps distinguish elevated PSA from benign prostatic enlargement.
👨⚕️ Lab Value📐 PSA density = total PSA / prostate volume🏥 Health
Total PSA (ng/mL)
Prostate volume (cm³ or mL)
Free PSA (%, optional)
Please enter valid values.
Formula & Reference
| Variable | Symbol | Formula | Units |
|---|---|---|---|
| PSA Density Calculator | — | PSA density = total PSA / prostate volume | ng/mL per cm³ |
Step-by-Step Examples
Example 1
Large Prostate, Low Density
PSA 6.4 ng/mL, prostate volume 80 cm³.
- Density = 6.4 / 80
- Density = 0.080
- Below 0.10 — the elevated PSA is plausibly explained by gland size
✓ 0.080 — low density
Example 2
Small Prostate, High Density
PSA 6.4 ng/mL, prostate volume 30 cm³.
- Density = 6.4 / 30
- Density = 0.213
- Same PSA, but well above the 0.15 threshold
- Gland size changes the interpretation entirely
✓ 0.213 — above threshold
Example 3
Borderline
PSA 5.2 ng/mL, prostate volume 40 cm³, free PSA 22%.
- Density = 5.2 / 40 = 0.130
- Falls in the intermediate band
- Free PSA 22% is a somewhat reassuring additional data point
✓ 0.130 — intermediate
Real-World Applications
Reducing Unnecessary Biopsy
PSA density helps identify men whose elevated PSA is attributable to benign enlargement rather than cancer.
Active Surveillance
Density is used in some active surveillance protocols as one criterion for monitoring rather than treating low-risk disease.
MRI Pathways
Density is increasingly combined with MRI findings to decide who needs a targeted biopsy.
Shared Decisions
Additional context helps make the biopsy conversation more informed rather than resting on a single PSA figure.
Common Mistakes to Avoid
⚠️
Using an estimated prostate volume
Density is only as good as the volume measurement. Guessed or palpation-based volumes produce a number with false precision — imaging-derived volume is needed.
⚠️
Treating 0.15 as a hard cutoff
The threshold is a convention drawn from research cohorts, not a biological boundary. Risk varies continuously and other factors matter.
⚠️
Testing PSA under conditions that distort it
Recent ejaculation, cycling, urinary infection, prostate examination, or instrumentation can all raise PSA. Some medications lower it substantially.
Frequently Asked Questions
What is PSA density? ▾
Total PSA divided by prostate volume, which adjusts for the fact that larger prostates produce more PSA independently of any disease.
What PSA density is concerning? ▾
A density at or above 0.15 ng/mL per cm³ is commonly cited as the threshold raising concern, though it is a convention rather than a definitive cutoff.
How is prostate volume measured? ▾
Usually by transrectal ultrasound or MRI. Digital rectal examination gives only a rough impression and is not adequate for density calculation.
Does 5-alpha reductase inhibitor use affect PSA? ▾
Yes, substantially. Finasteride and dutasteride typically roughly halve PSA within six to twelve months, and results need adjusting accordingly.
Should I make decisions based on this number? ▾
No. PSA density is one input among several — alongside free PSA, MRI, examination, family history, and age. Biopsy and treatment decisions belong with your urologist.