About this calculator
This calculator estimates albumin-corrected total calcium. Correction formulas are approximations and can be misleading in critical illness, kidney disease, acid-base disorders, very low albumin, or abnormal proteins.
Uses the common Payne-style albumin correction: corrected calcium = measured calcium + 0.8 × (4.0 − albumin) for mg/dL and g/dL units, or calcium + 0.02 × (40 − albumin) for mmol/L and g/L units. Ionized calcium is preferred in many critical contexts.
Source-mapped educational formula
Educational estimate only; not a diagnosis, prescription, or treatment plan.
Formula and method
Conventional: corrected calcium = measured calcium + 0.8 × (4.0 − albumin). SI: corrected calcium = measured calcium + 0.02 × (40 − albumin).
Limitations and when not to rely on this result
- Educational estimate only; not a diagnosis, prescription, or treatment plan.
- Result depends on accurate inputs and may not apply to complex medical situations.
- Use clinician judgment, local guidance, and urgent care pathways when symptoms are severe.
Frequently asked questions
What is corrected calcium? +
It estimates what total calcium might be if albumin were normal, because part of total calcium is albumin-bound.
Is corrected calcium always accurate? +
No. It is an estimate and can perform poorly in critical illness, kidney disease, acid-base disorders, and unusual protein states.
When is ionized calcium better? +
Ionized calcium is often preferred when symptoms, ICU illness, severe kidney disease, or acid-base disturbance is present.
Which units should I use? +
Use mg/dL calcium with g/dL albumin, or mmol/L calcium with g/L albumin.
Does this diagnose calcium disorders? +
No. Diagnosis requires clinical context and lab interpretation by a clinician.