Enter a laboratory total calcium and albumin value, selecting the units printed on your report. See the measured value alongside an albumin-adjusted estimate and its limitations.
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How to use it
Enter measured total calcium and serum albumin from the same sampling period. Choose mg/dL or mmol/L for calcium and g/dL or g/L for albumin. Start with empty fields, or use the example button. The optional date is included in the printable report.
Worked example and equation
At calcium 8.0 mg/dL and albumin 2.5 g/dL, the conventional adjustment is 8.0 + 0.8 × (4.0 − 2.5) = 9.2 mg/dL (approximately 2.30 mmol/L). The formula is applied only when albumin is below 4.0 g/dL; above that point this calculator displays the measured total calcium without a negative adjustment. For the SI calcium conversion, 1 mmol/L equals approximately 4.0078 mg/dL. This is a calculated estimate, not a measured ionized calcium concentration.
What the result can and cannot tell you
The result card uses 8.6–10.2 mg/dL as an illustrative total-calcium interval; compare with the range printed by your own laboratory. Albumin adjustment can misclassify calcium status, especially in chronic kidney disease, critical illness, acid-base changes and marked hypoalbuminemia. A normal-looking adjusted value does not exclude a problem with ionized calcium. If the result is unexpected, symptoms are present or treatment depends on it, discuss direct ionized-calcium measurement. Do not use this number alone to decide on calcium or vitamin D treatment.
Questions to take to a visit
- Does measured total calcium match symptoms and, when needed, ionized calcium?
- Could kidney function, albumin or acid-base status distort this estimate?
- Should magnesium, phosphate, PTH or vitamin D be measured, and when should we repeat the test?
Related tools and records
eGFR calculator · KFRE kidney failure risk · Health records and visit preparation · Understanding kidney test results · All calculators
Sources and update
- KDIGO CKD-MBD guideline, calcium discussion
- Carroll et al., paired calcium study and conventional formula
- MSD Manual Professional, hypocalcemia diagnosis
Sources reviewed September 30, 2026. General information; not a diagnosis or a substitute for care. No independent clinician review is claimed.