Estimated Plasma Volume Calculator

About this calculator

Plasma volume can’t be measured directly at the bedside without a dye-dilution or radioisotope test, so clinicians rely on regression formulas — most commonly the Kaplan or Strauss equations — that estimate it from sex, body weight, height and hematocrit, since these routinely available values correlate closely with actual measured plasma volume. Hematocrit drives the estimate because it reflects the ratio of red cells to total blood volume; a lower hematocrit relative to body size implies a larger relative plasma volume, and vice versa.

Cardiologists use estimated plasma volume status (ePVS) most often in heart failure, where fluid overload (plasma volume expansion) or excessive diuresis (plasma volume contraction) both affect prognosis and guide diuretic dosing decisions — an ePVS trend over serial visits can flag congestion before it’s clinically obvious. It’s also used in research settings to normalize hematology and biomarker values across patients of different body sizes.

This calculator takes sex, weight, height and hematocrit and returns the estimated plasma volume, using standard regression formulas built from these routine measurements.