What is the conversion factor between mg/dL and mmol/L for calcium?

Calcium has a molecular weight of 40.08 g/mol and a valence of 2. To convert mg/dL to mmol/L, divide by 4.008 (equivalently, multiply by 0.2495). To convert mmol/L to mg/dL, multiply by 4.008.

What is the relationship between mmol/L and mEq/L for calcium?

Because calcium is divalent (valence = 2), 1 mmol/L of calcium equals 2 mEq/L. To convert mmol/L to mEq/L multiply by 2; to convert mEq/L to mmol/L divide by 2.

What is the normal serum calcium range?

The standard normal range for total serum calcium is 8.5–10.5 mg/dL, which equals 2.12–2.62 mmol/L or 4.24–5.24 mEq/L. Some laboratories use 8.6–10.2 mg/dL as their reference interval — always check the reference range printed on your lab report.

What does a low calcium value mean?

A calcium level below 8.5 mg/dL (2.12 mmol/L) is called hypocalcemia. Causes include vitamin D deficiency, hypoparathyroidism, low magnesium, and kidney disease. Always confirm with a healthcare provider and consider correcting for albumin if albumin is low.

What does a high calcium value mean?

A calcium level above 10.5 mg/dL (2.62 mmol/L) is called hypercalcemia. Common causes include primary hyperparathyroidism, malignancy, and excess vitamin D or calcium supplementation. Significant elevations require medical evaluation.

Does this tool replace a laboratory test or clinical judgment?

No. This calculator is for educational and reference use only. All medical decisions about calcium management should be made by a qualified healthcare professional based on the full clinical context and verified laboratory results.

Calcium Unit Converter

Name: Calcium Unit Converter
Availability: InStock
Author: Nham Vu

Convert serum calcium values between mg/dL, mmol/L, and mEq/L with normal range indicators.

Enter Calcium Value

Value

From Unit

mg/dL (US standard) mmol/L (international SI) mEq/L (clinical / research)

Conversion Factors

From	To	Multiply by
mg/dL	mmol/L	0.2495
mmol/L	mg/dL	4.008
mmol/L	mEq/L	2.000
mEq/L	mmol/L	0.5000
mg/dL	mEq/L	0.4990
mEq/L	mg/dL	2.004

Based on Ca MW = 40.08 g/mol, valence = 2.

Enter a calcium value on the left to see conversions.

Normal Ranges at a Glance

Status	mg/dL	mmol/L	mEq/L
Low (hypocalcemia)	<8.5	<2.12	<4.25
Normal	8.5–10.5	2.12–2.62	4.25–5.25
High (hypercalcemia)	>10.5	>2.62	>5.25

Reference ranges are general guidelines. Individual laboratory normal values may vary slightly. Consult a healthcare professional for clinical interpretation.

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