mg ↔ mEq Converter

KCl has molecular weight 74.5. 600 mg ÷ 74.5 = 8.05 mmol KCl = 8.05 mmol K (since KCl is 1:1). Each mmol K = 1 mEq (valence 1), so 600 mg KCl ≈ 8 mEq K, which matches the "600 mg (8 mEq)" on US Klor-Con labels. Pick KCl as the ion and enter 600 mg.

Injections contain magnesium sulfate heptahydrate (MgSO₄·7H₂O), which carries 7 water molecules and weighs 246.47 g/mol, about twice the dry salt. US labels show the result: a 40 mg/mL bag is listed as 0.325 mEq of magnesium per mL, and 1 g of the 50% injection as 8.12 mEq. The converter uses the heptahydrate weight, so 1,000 mg gives 8.115 mEq, which rounds to the label's 8.12.

mmol is the SI unit (used in Europe, lab reports). mEq is the older clinical unit (used in US, drug labels, prescribing). Conversion: mEq = mmol × valence. So 5 mmol of K = 5 mEq (valence 1); 5 mmol of Ca = 10 mEq (valence 2).

Historical convention. US clinical pharmacology adopted mEq because it lets you compare ions on a charge-equivalence basis without thinking about valence. For example, you can directly compare 'serum K+ 4.5 mEq/L' against 'IV NaCl 154 mEq/L' regardless of valence. SI units (mmol) are theoretically cleaner but require the valence step for comparison.

On a prescription, the strength can refer to the salt (e.g. 600 mg KCl) or the elemental ion (e.g. 8 mEq K+). Labels in the US sometimes give both. The tool's salt entries (KCl, NaCl, CaCO3, MgSO4) handle salt-to-ion conversion directly. Pick the ion entry (K, Na, Ca, Mg) when the label is already in elemental form.