55 mg/dL LDL cholesterol to mmol/L

About LDL cholesterol and these units

LDL ("low-density lipoprotein") cholesterol is one of the lipid fractions reported on a standard lipid panel. LDL cholesterol appears in mg/dL on US lab reports and in mmol/L on UK, Canadian, Australian, and most European lab reports. The factor (0.02586) is shared with HDL, VLDL, and total cholesterol because all three reference the same cholesterol molecule.

Where the 0.02586 conversion factor comes from

mg/dL is a mass-per-volume unit. mmol/L is a moles-per-volume (molar concentration) unit. To convert between them you need the molecular weight of the substance, because that determines how many moles of it fit into a given mass.

For LDL cholesterol, the reference molecular weight is 386.65 g/mol (cholesterol). Working through the unit algebra:

• The factor is fixed by the molecular weight (386.65 g/mol (cholesterol)) together with the mass and volume prefixes of the two units, since a molar concentration counts molecules and a mass concentration weighs them.
• For LDL cholesterol this works out to 0.02586 mmol/L per mg/dL (multiply mg/dL by 0.02586 to get mmol/L).
• The inverse (mmol/L → mg/dL) is 38.67.

Step-by-step: converting 55 mg/dL of LDL cholesterol by hand

1. Start with the lab value: 55 mg/dL.
2. Look up the conversion factor for LDL cholesterol: 0.02586 mmol/L per mg/dL.
3. Multiply: 55 × 0.02586 = 1.422.
4. Attach the SI unit: 1.422 mmol/L.

Inverse check: 1.422 mmol/L ÷ 0.02586 = 55 mg/dL ✓.

Companion conversions for nearby LDL cholesterol values

If your lab reported a number close to but not exactly 55 mg/dL, the table below covers the surrounding range so you don't need to re-run the arithmetic.

A note on precision

Clinical chemistry assays for LDL cholesterol are typically precise to two or three significant figures. The exact factor 0.02586 is itself a rounded number, and the molecular weight that produces it (386.65 g/mol (cholesterol)) is conventionally rounded. So while the calculator displays 1.422 mmol/L for 55 mg/dL, reporting more decimal places than your original measurement supports is false precision.

Common questions

What is 55 mg/dL LDL cholesterol in mmol/L?

55 mg/dL of LDL cholesterol equals 1.422 mmol/L. The conversion factor for LDL cholesterol is 0.02586 (multiply mg/dL by 0.02586 to get mmol/L).

How do I convert mg/dL to mmol/L for LDL cholesterol?

LDL cholesterol has a conversion factor of 0.02586. Formula: 55 mg/dL × 0.02586 = 1.422 mmol/L. Inverse: 1.422 mmol/L ÷ 0.02586 = 55 mg/dL.

Why does LDL cholesterol have a different conversion factor than other biomarkers?

Each biomarker's mg/dL ↔ mmol/L factor is set by its molecular weight, because mmol/L is a molar concentration. For LDL cholesterol, the reference molecular weight is 386.65 g/mol (cholesterol), which gives a factor of 0.02586.

Where is mg/dL used and where is mmol/L used?

LDL cholesterol appears in mg/dL on US lab reports and in mmol/L on UK, Canadian, Australian, and most European lab reports. The factor (0.02586) is shared with HDL, VLDL, and total cholesterol because all three reference the same cholesterol molecule.

How precise should I report the converted value?

Lab assays for LDL cholesterol are typically precise to about two or three significant figures. Reporting more decimal places than your original measurement supports is false precision. For a reading of 55 mg/dL, 1.422 mmol/L is appropriate; further decimals are not.

Related conversions and reference

• Full blood test unit converter: convert any value for 50+ biomarkers in either direction.
• HbA1c ↔ average glucose converter: separate page for the HbA1c (% / mmol/mol) ↔ eAG conversion.
• Cholesterol ratio calculator: total/HDL and LDL/HDL ratios.