Corrected calcium calculator (albumin)
When albumin is low, total calcium looks lower than it really is; this tool estimates the corrected value.
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How to use it
- Enter units, total calcium and albumin.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Conventional units: corrected calcium = Ca + 0.8 × (4.0 - albumin), with mg/dL and g/dL. SI units: Ca + 0.02 × (40 - albumin), with mmol/L and g/L.
Example
Inputs: Units = mg/dL and g/dL, Total calcium = 8, Albumin = 2.5. Result: Corrected calcium: 9.2 mg/dL.
Limits and caveats
- The formula is approximate and can mislead in kidney failure and critical illness; measured ionized calcium is more accurate.
- Pick the units on your report; the tool does not detect them.
- An educational estimate that does not replace assessment by a doctor or pharmacist.
Questions about this tool
Why correct calcium?
About 40% of calcium is bound to albumin, so low albumin lowers total calcium while the active part stays the same.
What is the normal range?
About 8.5 to 10.5 mg/dL (2.1 to 2.6 mmol/L) in most labs, so check your lab range.
When is correction not needed?
When albumin is near 4 g/dL, or when ionized calcium has been measured directly.