Cholesterol Unit Converter (mg/dL and mmol/L)

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How we calculate it

Lipid results are reported in mg/dL in the United States and in mmol/L in most other countries. Converting between the two is exact arithmetic derived from molar mass, but it uses a different factor for each kind of molecule. Cholesterol — whether total, LDL or HDL — has a molar mass of 386.65 g/mol, giving 1 mmol/L = 38.67 mg/dL. Triglycerides, measured as triolein, give 1 mmol/L = 88.57 mg/dL. Using the cholesterol factor on a triglyceride value overstates it by a factor of roughly 2.3, and that error appears in hand conversions and in more than a few online converters. This tool applies the correct factor per field. Every input is optional, so a single value can be converted on its own, and where both total cholesterol and HDL are entered the non-HDL figure is derived as well, since the 2026 ACC/AHA guideline sets a non-HDL goal alongside every LDL one. A conversion changes only the units a result is written in. It does not convert between guidelines: the 2026 ACC/AHA guideline states its goals in mg/dL and the 2019 ESC/EAS guideline in mmol/L, and their risk categories are defined differently rather than being translations of one another.

Important limitations

• A unit conversion changes how a number is written, not what it means. Converting an LDL of 3.4 mmol/L to 131 mg/dL tells you nothing new about the result itself.
• Cholesterol and triglycerides use different conversion factors — 38.67 and 88.57 — because they are different molecules. Applying the cholesterol factor to triglycerides overstates them roughly 2.3-fold.
• The conversion arithmetic is exact, but the underlying laboratory measurement carries its own analytical variation, and results from different laboratories are not perfectly comparable.
• Thresholds differ between guidelines as well as between units. The AHA/ACC and ESC/EAS guidelines define their categories differently, so converting a number does not convert it between guidelines.
• Non-fasting and fasting samples can differ, particularly for triglycerides, so a converted value is only as comparable as the samples behind it.
• A converted value is not an interpretation. What a lipid result means depends on overall cardiovascular risk, family history, other conditions and medication.