Chloride Unit Converter
Chloride Unit Converter
Convert chloride between mmol/L, mEq/L and mg/dL. Chloride is monovalent, so mmol/L and mEq/L are the same number — and the result only means something once it is read against sodium.
Chloride converter
Monovalent — mmol/L = mEq/LChloride 102 mmol/L
Formula and conversion factors
mg/dL = mmol/L × 3.545
mEq/L = mmol/L (chloride is monovalent)
- 0.282087
- 10 ÷ 35.45, the atomic mass of chlorine — mg/dL × 10 ÷ MW gives mmol/L
- mEq/L
- chloride carries a single negative charge, so millimoles and milliequivalents are the same number
- sodium minus chloride
- the difference between the two, normally about 36 mmol/L, is the quickest bedside read on whether an acidosis has a raised gap
- 0.9% saline
- contains 154 mmol/L of chloride against a plasma value near 100, which is why large volumes produce a hyperchloraemic acidosis
Worked example
Chloride 102 mmol/L
102.0 mmol/L — the unit almost every laboratory reports
102.0 mmol/L = 102.0 mEq/L — chloride is monovalent, so the two are the same number
102.0 ÷ 0.282087 = 361.6 mg/dL, a mass unit not used on serum reports
Within the adult reference interval of 98–107 mmol/L
Thresholds across the units
| mmol/L | mEq/L | mg/dL | |
|---|---|---|---|
| Adult reference interval | 98 – 107 | 98 – 107 | 347 – 379 |
| Hypochloraemia | < 98 | < 98 | < 347 |
| Hyperchloraemia | > 107 | > 107 | > 379 |
| Chloride in 1 litre of 0.9% saline | 154 | 154 | 546 |
| Chloride in 1 litre of Hartmann’s solution | 111 | 111 | 394 |
| Chloride in 1 litre of Plasma-Lyte 148 | 98 | 98 | 347 |
Reading chloride against sodium
| Pattern | Suggests | Next step |
|---|---|---|
| Chloride high, bicarbonate low, gap normal | Hyperchloraemic (normal anion gap) acidosis | Saline load, diarrhoea, renal tubular acidosis — check the urine anion gap |
| Chloride low, bicarbonate high | Metabolic alkalosis | Vomiting, nasogastric loss, diuretics — measure a urinary chloride |
| Chloride low out of proportion to sodium | Raised anion gap acidosis, or a bromide interference | Calculate the gap; ask about bromide-containing preparations |
| Sodium minus chloride well above 36 | Unmeasured anions present | Calculate the anion gap formally and correct for albumin |
The electrolyte that only means something in company
Chloride is reported in mmol/L in the United Kingdom and in mEq/L in the United States, and the two are the same number, because chloride carries a single negative charge. The mg/dL column converts by 10 ÷ 35.45, the atomic mass of chlorine, or 0.2821 mmol/L per mg/dL. As with the other monovalent electrolytes, the arithmetic is trivial and the interpretation is not: a chloride read on its own is close to uninformative.
Its first use is in the anion gap. Chloride and bicarbonate are the two measured anions, so a chloride that rises as bicarbonate falls preserves the gap and points at a hyperchloraemic, normal anion gap acidosis, while a chloride that stays put as bicarbonate falls opens the gap and points at lactate, ketones, renal failure or a toxin. The difference between sodium and chloride, normally around 36 mmol/L, is the fastest bedside version of that question.
The second use is iatrogenic. A litre of 0.9% sodium chloride carries 154 mmol/L of chloride against a plasma value near 100, so large volumes reliably produce a hyperchloraemic metabolic acidosis; balanced crystalloids carry less — 111 mmol/L in Hartmann’s solution, 98 in Plasma-Lyte 148 — and do not. Randomised evidence in critically ill adults has favoured balanced solutions over saline for major adverse kidney events, and recognising a saline-induced acidosis prevents a fruitless search for lactate or ketones.
Two further points are worth holding. A low chloride with a high bicarbonate is a metabolic alkalosis, and a urinary chloride below about 20 mmol/L identifies the saline-responsive causes — vomiting, nasogastric loss, diuretics that have worn off — from the saline-resistant ones such as hyperaldosteronism. And chloride is measured by ion-selective electrodes that some halides interfere with, so bromide, and at high concentrations salicylate on certain analysers, can produce a spuriously high chloride and an artefactually low or negative anion gap.
Frequently asked questions
Is mmol/L the same as mEq/L for chloride?
Yes. Chloride is monovalent, so one millimole carries one milliequivalent of charge and the two numbers are identical. A chloride of 102 mmol/L is 102 mEq/L, and no conversion should be applied.
How do I convert chloride from mg/dL to mmol/L?
Multiply by 0.2821, which is 10 divided by the atomic mass of chlorine, 35.45. A value of 360 mg/dL is 101.6 mmol/L. To go the other way, multiply the mmol/L figure by 3.545.
Why does saline cause a high chloride?
A litre of 0.9% sodium chloride contains 154 mmol/L of chloride against a plasma value near 100. Large volumes therefore raise plasma chloride, displace bicarbonate and produce a hyperchloraemic metabolic acidosis with a normal anion gap.
What does the sodium minus chloride difference tell me?
It is a quick screen for the anion gap. The difference is normally about 36 mmol/L; a much larger difference suggests unmeasured anions and a raised gap, while a normal difference with a low bicarbonate suggests a hyperchloraemic acidosis.
Can a chloride result be falsely high?
Yes. Chloride is measured by ion-selective electrodes that other halides can cross-react with, so bromide — and at high concentrations salicylate on some analysers — produces a spuriously high chloride and an artefactually low or even negative anion gap.
Related calculators
References
- Semler MW, Self WH, Wanderer JP, et al. Balanced crystalloids versus saline in critically ill adults. N Engl J Med. 2018;378(9):829–839.
- Berend K, van Hulsteijn LH, Gans ROB. Chloride: the queen of electrolytes? Eur J Intern Med. 2012;23(3):203–211.
- Rifai N, Horvath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018.
Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/