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Calcium (Ca) Unit Converter
Calcium is the most abundant mineral in the human body, essential for bone mineralization, muscle contraction, nerve transmission, and blood clotting. In the blood, calcium exists in three forms: ionized (free/physiologically active ~50%), protein-bound (mostly to albumin ~40%), and complexed with anions (like citrate or phosphate ~10%).
Serum calcium levels are tightly regulated by Parathyroid Hormone (PTH), Vitamin D, and Calcitonin.[Image of calcium homeostasis regulation by PTH and Vitamin D] Disorders of calcium metabolism are common; Hypercalcemia is frequently caused by primary hyperparathyroidism or malignancy, while Hypocalcemia can result from hypoparathyroidism, Vitamin D deficiency, or renal failure. This converter handles all common reporting units: mg/dL (US), mmol/L (International), and mEq/L (common in critical care).
SI / Standard
RecommendedMillimoles or Milliequivalents per liter.
Mass Units
Clinical Context
Total Calcium Reference Range: Typically 8.5 – 10.5 mg/dL (2.1 – 2.6 mmol/L). Ionized calcium (free calcium) is physiologically more important but harder to measure; its normal range is 4.5 – 5.6 mg/dL (1.1 – 1.4 mmol/L).
Because ~40% of calcium is bound to albumin, Total Calcium must be “corrected” in patients with hypoalbuminemia. The formula is: Corrected Ca = Measured Ca + 0.8 * (4.0 – Serum Albumin). The conversion factor is based on MW 40.078 g/mol: 1 mmol/L ≈ 4.0 mg/dL.
Clinical References
How to Use This Calculator
Follow these steps to get accurate clinical conversions instantly.
Enter Values
Input your laboratory results into the corresponding unit field (e.g., mg/dL). You can use either dot or comma decimals.
Automatic Conversion
The calculator works in real-time. As you type in one field, all other units (like mmol/L) are instantly updated.
Verify Units
Check the SI Units section. mmol/L is the international standard, while mEq/L is common in dialysis.
Reset
Use the Clear button to reset all fields before starting a new calculation.
Frequently Asked Questions & Tips
Yes. Because calcium has a valency of +2 ($Ca^{2+}$), one millimole contains two milliequivalents of charge.
No. This calculator only converts units. To calculate corrected calcium, use the Albumin-Corrected Calcium calculator.