Corrected Calcium Calculator

About this calculator

This calculator applies the Payne formula to adjust a measured total serum calcium result for an abnormal albumin level: corrected calcium = measured calcium + 0.8 × (4.0 − albumin in g/dL). About 40% of calcium in blood is bound to albumin, so low albumin (common in hospitalized or malnourished patients) makes total calcium read artificially low even though the biologically active, ionized fraction is normal.

Clinicians, nurses and lab technicians use this correction to avoid mistaking hypoalbuminemia for true hypocalcemia, and to decide whether a low or high calcium result actually needs further workup. It is a bedside estimate only — an ionized calcium blood test is the definitive check when the result is borderline.