Corrected Calcium Calculator

How it is calculated

The tool adds a correction to the measured total calcium: corrected Ca = Ca + 0.8 × (4.0 − albumin). Calcium is in mg/dL and albumin in g/dL; the engine does no unit conversion, so values must already be in those units. The 4.0 g/dL is the fixed normal albumin the formula assumes. Because the term is signed, albumin below 4.0 raises the result and albumin above 4.0 lowers it. The answer is shown in mg/dL with two decimals. This is an estimate for total calcium, not a replacement for a measured ionized calcium.

Common mistakes

• Entering calcium in mmol/L (for example 2.1) or albumin in g/L (for example 25). The formula expects mg/dL and g/dL and will give nonsense otherwise.
• Entering ionized calcium instead of total calcium; the correction is meant only for total calcium.
• Assuming the correction only goes upward: with albumin above 4.0 g/dL, 8.0 with albumin 4.5 becomes 7.60, lower than measured.
• Swapping the two fields, so the albumin value is read as calcium.
• Treating the corrected figure as a diagnosis rather than a bedside estimate to be confirmed when borderline.