HDL Cholesterol Unit Converter

In short HDL Cholesterol is reported in mg/dL in some countries and mmol/L in others, and the two are related by a fixed factor: 1 mg/dL = 0.0258629 mmol/L, so to go the other way you divide by 38.6654. 40 mg/dL is 1.0 mmol/L; 50 mg/dL is 1.3 mmol/L; 60 mg/dL is 1.6 mmol/L. The factor is not arbitrary — it comes from the molar mass, because cholesterol has a molar mass of 386.65 g/mol, and HDL measures the same molecule, and that is why every analyte has its own factor rather than one shared conversion. HDL uses the same factor as total cholesterol because it is the same molecule — what differs is the lipoprotein carrying it, not the substance being counted. That is also why the numbers are small: HDL is typically around a quarter of the total, so the SI figure often lands near 1 and is easy to mistake for a different scale entirely. This converts units. It does not interpret results, does not compare your value against a reference interval, and is not a substitute for the clinician who ordered the test — reference intervals differ between laboratories, methods and populations.