Unit Conversion
Electrolyte Conversion Calculator
Converts an electrolyte amount between milligrams, millimoles (mmol) and milliequivalents (mEq) — for IV fluids, supplements and replacement doses.
Sodium (Na⁺) in mg
2299mg
100 mmol = 2299 mg
Clinical significance
Convert
MW 22.99 g/mol · valence 1
The amount of sodium in mmol.
Decimal places shown. Very large or small answers switch to scientific notation.
Common electrolyte doses
In every unit
100 mmol of Sodium (Na⁺) expressed as mg, mmol and mEq.
Electrolyte reference table
| Electrolyte | Symbol | Molecular weight | Valence | mEq per mmol | mg per mEq |
|---|---|---|---|---|---|
| Sodium (Na⁺) | Na | 22.99 | 1 | 1 | 22.99 |
| Potassium (K⁺) | K | 39.10 | 1 | 1 | 39.10 |
| Calcium (Ca²⁺) | Ca | 40.08 | 2 | 2 | 20.04 |
| Magnesium (Mg²⁺) | Mg | 24.31 | 2 | 2 | 12.15 |
| Chloride (Cl⁻) | Cl | 35.45 | 1 | 1 | 35.45 |
| Bicarbonate (HCO₃⁻) | HCO₃ | 61.02 | 1 | 1 | 61.02 |
| Phosphate (PO₄³⁻) | PO₄ | 94.97 | 3 | 3 | 31.66 |
mg = mmol × Molecular Weight
mg = mEq × (MW ÷ Valence)
The reverse conversions divide instead of multiply. MW ÷ valence is the equivalent weight — the mass that carries one unit of charge. For monovalent ions (valence 1) it equals the molecular weight, so 1 mmol = 1 mEq.
100 × 22.99 = 2299 mg
References
- Stockton SJ. Stoklosa and Ansel's Pharmaceutical Calculations. 16th ed. Philadelphia: Wolters Kluwer; 2021.
- Bureau International des Poids et Mesures. The International System of Units (SI Brochure). 9th ed. Sèvres: BIPM; 2019. Source
Common questions
A millimole counts particles; a milliequivalent counts charge. mEq = mmol × valence, so for sodium, potassium and chloride they are the same number, while 1 mmol of calcium or magnesium is 2 mEq.
Of the ion alone. To find how much salt to weigh, use the salt's own molecular weight — for example KCl is 74.55 g/mol, so 1 mmol of potassium comes with 74.55 mg of KCl.
20 × 39.1 ÷ 1 = 782 mg of potassium ion, which is supplied by about 1.49 g of potassium chloride.
At body pH phosphate exists as a mix of HPO₄²⁻ and H₂PO₄⁻, so its average charge is not a whole number. That is why phosphate replacement is usually prescribed in mmol rather than mEq.
Prepared by the PharmaWallah student team. Verify results with your textbook or instructor. Report an error · Editorial policy