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BIPM-ratified constants · v1.0

Converter

Cholesterol, units converter (mg/d l ↔ mmol/l) calculator.

Convert total, LDL, HDL cholesterol and triglycerides between mg/dL and mmol/L using the correct molar-mass factor for each lipid type.

From

total

cholesterol

200 cholesterol =5.172Converted Cholesterol Value

Equivalents

Precision: 6 dp · Notation: Decimal · 2 units

US to SI

mg/dL → mmol/Lmgdl_to_mmoll5.172

SI to US

mmol/L → mg/dLmmoll_to_mgdl7,734

Common pairings

1 cholesterolequals0.026 mgdl_to_mmoll
1 cholesterolequals38.67 mmoll_to_mgdl
1 cholesterolequals0.026 mgdl_to_mmoll
1 cholesterolequals38.67 mmoll_to_mgdl
1 cholesterolequals0.026 mgdl_to_mmoll
1 cholesterolequals38.67 mmoll_to_mgdl
1 cholesterolequals0.026 mgdl_to_mmoll
1 cholesterolequals38.67 mmoll_to_mgdl

The conversion

How the value
is computed.

How the Cholesterol Units Converter Works

Laboratory reports around the world express cholesterol and triglyceride concentrations in one of two units: milligrams per deciliter (mg/dL), the standard in the United States, or millimoles per liter (mmol/L), the SI unit used throughout Europe, Canada, Australia, and most of Asia. The cholesterol units converter bridges these two systems using a division or multiplication by a lipid-specific conversion factor determined by molecular weight.

The Conversion Formula

The governing equations are simple and exact:

  • mg/dL to mmol/L: mmol/L = mg/dL ÷ k
  • mmol/L to mg/dL: mg/dL = mmol/L × k

The constant k depends on the type of lipid being measured, because cholesterol fractions and triglycerides differ substantially in molar mass. Selecting the wrong lipid type introduces an error of more than 100 percent in the result.

Conversion Factor for Cholesterol Fractions (k = 38.67)

Total cholesterol, LDL cholesterol, HDL cholesterol, and non-HDL cholesterol all share a molar mass of approximately 386.65 g/mol. The conversion factor is derived by dividing the molar mass by 10: 386.65 ÷ 10 ≈ 38.67. This factor applies equally to every cholesterol fraction because each measurement reports the mass of the cholesterol molecule itself, regardless of the lipoprotein particle (VLDL, LDL, HDL) that transports it through the bloodstream.

Conversion Factor for Triglycerides (k = 88.57)

Triglycerides are substantially larger molecules. Their average molar mass is approximately 885.7 g/mol, yielding a conversion factor of 885.7 ÷ 10 ≈ 88.57. Applying the cholesterol factor of 38.67 to a triglyceride value would produce a number roughly 2.3 times too low, a clinically significant distortion that could mask severely elevated triglyceride concentrations.

Input Variables Explained

  • Cholesterol Value: The numeric reading from a lipid panel report. Enter the number exactly as it appears on the report, in the units that match the selected conversion direction.
  • Lipid Type: Determines which conversion factor (k) to apply. Select Cholesterol (Total / LDL / HDL / Non-HDL) for any cholesterol fraction to use k = 38.67, or Triglycerides to use k = 88.57.
  • Conversion Direction: Select mg/dL → mmol/L to convert from US units to international SI units, or mmol/L → mg/dL to convert in the opposite direction.

Worked Examples

Example 1 — Total Cholesterol (mg/dL to mmol/L)

A US lipid panel reports total cholesterol of 210 mg/dL. Converting to mmol/L: 210 ÷ 38.67 = 5.43 mmol/L. According to the National Heart, Lung, and Blood Institute (NHLBI), desirable total cholesterol is below 5.17 mmol/L (200 mg/dL), placing this result in the borderline-high category and warranting a conversation about diet and lifestyle.

Example 2 — LDL Cholesterol (mmol/L to mg/dL)

A Canadian report shows an LDL of 3.4 mmol/L. Converting to US units: 3.4 × 38.67 = 131.5 mg/dL. US guidelines classify LDL between 130 and 159 mg/dL as borderline-high, meaning lifestyle modification is typically recommended for this patient.

Example 3 — Triglycerides (mg/dL to mmol/L)

A fasting triglyceride of 150 mg/dL — the upper boundary of normal — converts to 150 ÷ 88.57 = 1.69 mmol/L. This closely matches the international normal-range ceiling of 1.7 mmol/L, confirming concordance between the two reporting systems as documented in CDC NHANES Cholesterol Laboratory Methods.

Clinical Reference Ranges in Both Units

  • Total Cholesterol: Desirable <200 mg/dL (<5.17 mmol/L) | Borderline-high 200–239 mg/dL (5.17–6.18 mmol/L) | High ≥240 mg/dL (≥6.21 mmol/L)
  • LDL Cholesterol: Optimal <100 mg/dL (<2.59 mmol/L) | Near-optimal 100–129 mg/dL (2.59–3.34 mmol/L) | Borderline-high 130–159 mg/dL (3.37–4.11 mmol/L)
  • HDL Cholesterol: Low (independent risk factor) <40 mg/dL (<1.03 mmol/L) | Protective ≥60 mg/dL (≥1.55 mmol/L)
  • Triglycerides: Normal <150 mg/dL (<1.69 mmol/L) | Borderline-high 150–199 mg/dL | High 200–499 mg/dL | Very high ≥500 mg/dL (≥5.65 mmol/L)

Why Two Unit Systems Exist

The mg/dL convention dates to early 20th-century US clinical chemistry, where mass-per-volume measurements were already embedded in laboratory workflow and regulatory frameworks. The mmol/L system emerged from the broader global adoption of International System (SI) units in scientific and medical practice. Neither is more accurate — they are mathematically equivalent expressions of the same concentration — but misreading one as the other without conversion can produce a roughly 38-fold numerical error for cholesterol values or an 88-fold error for triglycerides, with potentially serious consequences for diagnosis and treatment decisions.

Methodology and Sources

Conversion factors used here are derived from molar masses accepted in clinical biochemistry and consistent with lipid quantification methods described in New Methods for Calculating LDL-Cholesterol and Related Lipid Parameters (PMC, 2025). Standardized measurement protocols and reference population data are drawn from the CDC NHANES Cholesterol Laboratory Methods program, which provides national surveillance benchmarks for lipid testing accuracy. Clinical reference ranges reflect adult cardiovascular risk thresholds established by the NHLBI.

Reference

Frequently asked questions

What is the conversion factor from mg/dL to mmol/L for cholesterol?
The conversion factor for total, LDL, HDL, and non-HDL cholesterol is 38.67. Divide any cholesterol value in mg/dL by 38.67 to obtain the equivalent in mmol/L. For example, a total cholesterol of 193 mg/dL equals 193 ÷ 38.67 = 4.99 mmol/L, which falls in the desirable range below 5.17 mmol/L per NHLBI guidelines.
Why do triglycerides use a different conversion factor than cholesterol?
Triglycerides use a factor of 88.57 instead of 38.67 because their average molar mass is approximately 885.7 g/mol, compared to cholesterol's 386.65 g/mol. The conversion factor is derived by dividing molar mass by 10. Using the cholesterol factor on a triglyceride value produces a result more than double the correct answer, which could mask a dangerously elevated reading.
How do I convert LDL cholesterol from mmol/L to mg/dL?
Multiply the LDL value in mmol/L by 38.67 to get mg/dL. For example, an LDL of 2.6 mmol/L — a common European optimal target — equals 2.6 × 38.67 = 100.5 mg/dL. This closely matches the US guideline optimal LDL threshold of below 100 mg/dL, confirming that both figures describe the same cardiovascular risk boundary expressed in different units.
What is 200 mg/dL total cholesterol in mmol/L?
A total cholesterol of 200 mg/dL converts to 200 ÷ 38.67 = 5.17 mmol/L. This value represents precisely the boundary between the desirable and borderline-high categories as defined by the NHLBI. Adults without additional cardiovascular risk factors are generally considered to have desirable cholesterol when their total falls below this threshold in either unit system.
Which countries use mmol/L for cholesterol and which use mg/dL?
The United States primarily reports cholesterol and triglycerides in mg/dL. Canada, the United Kingdom, Australia, most of continental Europe, and the majority of countries worldwide use mmol/L as the SI standard. International travelers, immigrants, and patients comparing lab results from different healthcare systems benefit from a reliable cholesterol units converter to avoid misinterpreting their lipid values.
Can I use the same conversion factor for HDL, LDL, and total cholesterol?
Yes. Total cholesterol, LDL cholesterol, HDL cholesterol, and non-HDL cholesterol all use the same conversion factor of 38.67, because each fraction measures the cholesterol molecule itself regardless of which lipoprotein carrier transports it. Only triglycerides require a separate factor of 88.57, reflecting their substantially larger and chemically distinct molecular structure. Applying the wrong factor introduces a large and clinically significant numerical error.