About 40% of calcium in blood is bound to albumin. When albumin is low, total calcium looks falsely low even if the active (ionised) calcium is normal.
How to use the Corrected Calcium Calculator
- Total calcium
- Albumin
- Normal albumin
Results update as you type, and every field accepts the units shown in its menu.
How it works
For every 1 g/dL that albumin is below 4.0, 0.8 mg/dL is added to the measured calcium.
Inputs explained
| Field | What to enter |
|---|---|
| Total calcium | In mg/dL |
| Albumin | In g/dL |
| Normal albumin | In g/dL |
What each result means
- Corrected calcium = [Total calcium] + 0.8×([Normal albumin] – [Albumin])
- Corrected calcium (mmol/L) = [Corrected calcium] ÷ 4.008
Example values
How the main result changes when Total calcium changes and everything else stays at the example values above:
| Total calcium (mg/dL) | Corrected calcium (mg/dL) |
|---|---|
| 4.1 | 4.9 |
| 6.15 | 6.95 |
| 8.2 | 9 |
| 10.25 | 11.05 |
| 12.3 | 13.1 |
| 16.4 | 17.2 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
Corrected Ca (mg/dL) = measured Ca + 0.8 × (4.0 − albumin g/dL)Worked example
Inputs — Total calcium: 8.2 mg/dL; Albumin: 3 g/dL; Normal albumin: 4 g/dL.
Results — Corrected calcium = 9 mg/dL; Corrected calcium (mmol/L) = 2.25 mmol/L.
Frequently asked questions
Is corrected calcium always reliable?
It is an approximation; measuring ionised calcium directly is more accurate.
How do I convert units?
Divide mg/dL by 4.008 for mmol/L.
What formula does the Corrected Calcium Calculator use?
Corrected Ca (mg/dL) = measured Ca + 0.8 × (4.0 − albumin g/dL).