How do I convert Ionized calcium from mg/dL to mmol/L?

mmol/L = mg/dL × 0.2495. For example, 5 mg/dL equals 1.25 mmol/L.

How many mmol/L are 5 mg/dL?

5 mg/dL equal 1.25 mmol/L (Ionized calcium).

Electrolytes & minerals

mmol/L = mg/dL × 0.2495

Enter a value in any unit and all other units fill in.

mg/dL mmol/L

mg/dL → mmol/L	mmol/L = mg/dL × 0.2495
mmol/L → mg/dL	mg/dL = mmol/L × 4.008

Highlighted: values inside the adult reference range.

4.81 – 5.611 mg/dL = 1.2 – 1.4 mmol/L

Source: MedlinePlus (NLM): Calcium - ionized · Last reviewed: 2026-10-14