Prostate Cancer Tool
PSA Doubling Time Calculator
Enter 2 or more dated PSA results to estimate how quickly PSA is doubling or halving, with a chart of your results.
DT = ln 2 × Δt ÷ ln(PSA2 / PSA1)
Enter at least 2 PSA results, then select Generate.
PSA over time
The 6-month comparison uses the reading closest to the calendar date 6 months before your last result. These are two-point estimates, so normal lab variation can move them a lot, especially over short intervals. Published PSA doubling times usually fit a regression line through 3 or more results. Review results with the treating clinician.
How is PSA doubling time calculated?
PSA doubling time is the number of months it would take PSA to double at its current rate of change. This calculator treats the change between two results as steady exponential growth:
DT = ln 2 × Δt ÷ ln(PSA2 / PSA1)
For example, a PSA that rises from 2.0 to 4.0 ng/mL over 10 months has a doubling time of 10 months. When PSA is falling, the same calculation gives a halving time instead.
What do the two results show?
- Last 2 results compares your two most recent PSA values.
- Last result vs. 6 months prior compares your latest PSA with the reading closest to 6 months earlier, and flags it if no reading falls within 30 days of that date.
Is my information saved?
No. The calculation runs in your browser, and nothing you enter is saved or sent anywhere.
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