Calcium Unit Converter (mg/dL ↔ mmol/L)

Health Updated 14 Jun 2026

Convert a serum calcium result between mg/dL and mmol/L. Lab reports use different units in different countries, so this converter lets you read any calcium value in the units you're familiar with. Enter the value, choose the direction, and get the equivalent instantly.

Rates and fees change frequently. Always confirm the current figures with the official authority before relying on this result.
  • Conversion uses the calcium molar mass factor of 0.2495.

Formula

mmol/L = mg/dL × 0.2495; mg/dL = mmol/L ÷ 0.2495
  • The conversion factor 0.2495 comes from calcium's atomic weight (about 40.08 g/mol) and the 10× difference between deciliters and liters.
  • To go from mg/dL to mmol/L, multiply by 0.2495.
  • To go from mmol/L to mg/dL, divide by 0.2495 (or multiply by about 4.008).
  • Typical adult total serum calcium is roughly 8.5–10.2 mg/dL, or 2.12–2.55 mmol/L.
  • Total calcium is affected by albumin — if albumin is low, consider a corrected-calcium calculation for a truer picture.

9.5 mg/dL to mmol/L

Inputs
  • Calcium Value: 9.5
  • Convert: to

9.5 mg/dL × 0.2495 = 2.37 mmol/L — a normal total serum calcium level.

Frequently asked questions

What is the normal calcium range?
Total serum calcium is typically about 8.5–10.2 mg/dL (2.12–2.55 mmol/L) in adults, though exact reference ranges vary slightly by lab.
Why do units differ between labs?
The United States commonly reports calcium in mg/dL, while most other countries use mmol/L (SI units). The value is the same — only the unit changes.
What is the conversion factor?
Multiply mg/dL by 0.2495 to get mmol/L, or divide mmol/L by 0.2495 to get mg/dL. The factor is based on calcium's molar mass.
Should I correct for albumin?
If albumin is low, total calcium can read falsely low. A corrected-calcium calculation adjusts for this, but ionized (free) calcium is the most accurate measure when precision matters.

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