Electrolytes & minerals

Ionized calcium unit converter

Free, active calcium

Also known as: Ionised calcium, iCa, Ca2+, Free calcium, Freies Calcium, Calcium ionisé

Converter

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

mmol/L mEq/L mg/dL mg/L µmol/L µg/dL

Worked example

1.3 mmol/L (middle of the reference range) = 5.21 mg/dL

Conversion formulas

mEq/L	mEq/L = mmol/L × 2	mmol/L = mEq/L × 0.5
mg/dL	mg/dL = mmol/L × 4.008	mmol/L = mg/dL × 0.2495
mg/L	mg/L = mmol/L × 40.08	mmol/L = mg/L × 0.02495
µmol/L	µmol/L = mmol/L × 1000	mmol/L = µmol/L × 0.001
µg/dL	µg/dL = mmol/L × 4008	mmol/L = µg/dL × 0.0002495

Reference range

Unit	Adults
mmol/L	1.2 – 1.4
mEq/L	2.4 – 2.8
mg/dL	4.81 – 5.611
mg/L	48.1 – 56.11
µmol/L	1200 – 1400
µg/dL	4810 – 5611

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

Note from the source: Adults 4.8-5.6 mg/dL (1.20-1.40 mmol/L) (MedlinePlus)

Frequently asked questions

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

mg/dL = mmol/L × 4.008. In the other direction: mmol/L = mg/dL × 0.2495.

What is the reference range of Ionized calcium?

For adults the range is 1.2 – 1.4 mmol/L (MedlinePlus (NLM): Calcium - ionized). Reference ranges differ between laboratories and partly by sex and age; use the range printed on your lab report.

Which units are used for Ionized calcium?

Common units are mmol/L, mEq/L, mg/dL, mg/L, µmol/L, µg/dL.