meq/l to mmol/l Converter

Published By: Calculator Academy Team

Last Updated: December 11, 2025

meq/l to mmol/l converter

Convert mEq/L to mmol/L or mmol/L to mEq/L for sodium, potassium, chloride, bicarbonate, calcium, magnesium, and phosphate ions.

mEq/L → mmol/L
mmol/L → mEq/L
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Quick overview: mEq/L to mmol/L

The relationship between mEq/L and mmol/L depends on the ion’s absolute charge (|z|): mmol/L = mEq/L ÷ |z|.

  • For Na⁺, K⁺, Cl⁻ (|z| = 1): 10 mEq/L = 10 mmol/L
  • For HCO₃⁻ (|z| = 1): 24 mEq/L = 24 mmol/L
  • For Ca²⁺, Mg²⁺ (|z| = 2): 10 mEq/L = 5 mmol/L
  • For PO₄³⁻ (|z| = 3): 9 mEq/L = 3 mmol/L

The converter applies this rule automatically once you enter the value in mEq/L and choose the corresponding ion or electrolyte.

This page explains how to convert milliequivalents per liter (mEq/L) to millimoles per liter (mmol/L) for common clinical ions. For monovalent ions like sodium (Na⁺) or potassium (K⁺), the numeric values in mEq/L and mmol/L are the same. For divalent ions such as calcium (Ca²⁺) or magnesium (Mg²⁺), you divide the mEq/L value by 2 to obtain mmol/L.

mEq/L to mmol/L Formula

mEq/L is a concentration measure that incorporates both the amount of substance and its electrical charge. mmol/L is a more purely chemical measure that reflects the number of particles regardless of charge. The two are linked through the ion’s valence (absolute charge, |z|) using:

  • mEq/L = mmol/L × |z|
  • mmol/L = mEq/L ÷ |z|

Here, |z| is the absolute value of the ion’s charge. Some common examples:

  • Na⁺, K⁺, Cl⁻, HCO₃⁻: |z| = 1
  • Ca²⁺, Mg²⁺: |z| = 2
  • PO₄³⁻: |z| = 3

Once you know the charge, the conversion is straightforward. For example, 10 mEq/L of Ca²⁺ corresponds to 10 ÷ 2 = 5 mmol/L, while 10 mEq/L of Na⁺ corresponds to 10 ÷ 1 = 10 mmol/L.

mEq/L to mmol/L conversion table

The table below shows example conversions for a 10 mEq/L concentration of several common ions using the relationship mmol/L = mEq/L ÷ |z|.

Ion Typical |z| 10 mEq/L in mmol/L
Sodium (Na⁺) 1 10 mmol/L
Potassium (K⁺) 1 10 mmol/L
Chloride (Cl⁻) 1 10 mmol/L
Bicarbonate (HCO₃⁻) 1 10 mmol/L
Calcium (Ca²⁺) 2 5 mmol/L
Magnesium (Mg²⁺) 2 5 mmol/L
Phosphate (PO₄³⁻) 3 3.33 mmol/L

In practice, the lab often reports either mmol/L or mEq/L depending on the analyte and local conventions. Understanding the role of the ion’s charge makes it easy to move between the two and compare results across different references or calculators.

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