Cholesterol Units Converter (mg/dL to mmol/L)
Convert cholesterol values between mg/dL and mmol/L for total cholesterol, LDL, HDL, and triglycerides. Enter your lab reading and instantly see the converted value with its interpretation category.
Cholesterol Units Converter (mg/dL ↔ mmol/L)
Cholesterol Units Conversion Formula
Where:
- \(38.67\) — molecular weight of cholesterol (g/mol), used for total cholesterol, LDL, and HDL
- \(88.57\) — molecular weight of triglycerides (g/mol, as triolein)
The conversion is a simple molar conversion: the United States reports lipid concentrations in milligrams per deciliter (mg/dL), while most other countries use millimoles per liter (mmol/L). Because cholesterol and triglycerides have different molecular weights, each requires its own factor.
Cholesterol Converter – Calculation Example
Example: a lab report from a European clinic shows total cholesterol of 4.9 mmol/L, and you want to compare it with US reference ranges given in mg/dL.
\[ 4.9 \ \text{mmol/L} \times 38.67 = 189.5 \ \text{mg/dL} \approx 190 \ \text{mg/dL} \]
Result: 4.9 mmol/L \(\approx\) 190 mg/dL, which falls below 200 mg/dL (5.2 mmol/L) and is classified as desirable.
Conversely, a US reading of 190 mg/dL converts to \(190 / 38.67 \approx 4.91\) mmol/L — the calculator's default values.
How to Use the Calculator
- Open the Lipid type dropdown and select the analyte from your lab report: Total cholesterol, LDL cholesterol, HDL cholesterol, or Triglycerides. This matters because triglycerides use a different conversion factor than the three cholesterol measures.
- Enter your reading in the Cholesterol value field.
- Choose the unit of your reading — mg/dL or mmol/L — using the unit selector next to the input field. The calculator converts your value to the other unit.
- Read the Converted value, which shows both units, along with the Interpretation and a table of Typical reference ranges for that lipid.
Why Two Units Exist and What They Mean
Medical laboratories around the world express blood lipid concentrations in two different ways. In the United States, values are reported as mass per volume — milligrams per deciliter (mg/dL). In Canada, Europe, Australia, and much of the rest of the world, values are reported as amount of substance per volume — millimoles per liter (mmol/L). If you compare your lab report with a foreign guideline, a website, or a research paper, the numbers can look wildly different even though they describe the same concentration. For example, a total cholesterol of 200 mg/dL is the same as 5.2 mmol/L.
The conversion between the two units depends on the molecular weight of the substance being measured. Cholesterol (total, LDL, and HDL all measure the same molecule) has a molecular weight of about 38.67 g/mol, so 1 mmol/L equals 38.67 mg/dL. Triglycerides are reported as if they were triolein, with a molecular weight of about 88.57 g/mol, so 1 mmol/L of triglycerides equals 88.57 mg/dL. This is why you cannot use a single conversion factor for an entire lipid panel — a common mistake that leads to errors of more than a factor of two for triglycerides.
The interpretation shown alongside the converted value uses widely accepted adult reference thresholds, primarily from US guidelines. Total cholesterol below 200 mg/dL (5.2 mmol/L) is considered desirable; LDL below 100 mg/dL (2.6 mmol/L) is optimal for most adults; HDL of 60 mg/dL (1.6 mmol/L) or higher is considered protective; and triglycerides below 150 mg/dL (1.7 mmol/L) are considered normal. Note that for HDL, higher is better — the reverse of the other lipids.
Assumptions and Limitations
- The reference categories shown are general adult thresholds and do not account for personal risk factors. People with diabetes, existing heart disease, or a family history of high cholesterol may be given stricter targets (for example, an LDL goal below 70 mg/dL / 1.8 mmol/L) by their doctor.
- Children, pregnant women, and people on lipid-lowering medication have different reference ranges; interpret their results with a healthcare provider.
- The triglyceride factor of 88.57 assumes triglycerides are measured as triolein, which is the standard convention in clinical laboratories.
- The calculator performs a pure unit conversion — it does not replace medical advice. A single reading can be affected by recent meals, illness, or medications, so always discuss abnormal results with your doctor.
Practical Tips
When reading a full lipid panel from another country, convert each value separately: total cholesterol, LDL, and HDL share one factor, but triglycerides need their own. If you also monitor blood glucose, note that glucose uses yet another factor (18) — our Blood Sugar Units Converter handles that conversion for you. For converting other laboratory and engineering units, such as concentrations in ppm or mg/L, we have dedicated tools as well.
Frequently Asked Questions
Is there a quick rule of thumb for converting cholesterol without a calculator?
For a rough mental conversion, divide mg/dL by 40 to get mmol/L, or multiply mmol/L by 40 to get mg/dL. For example, 200 mg/dL ≈ 5 mmol/L. The exact factor is 38.67, so this shortcut is off by about 3% — fine for a quick sanity check, but use the precise factor when comparing against clinical thresholds, since small differences can shift you across a category boundary.
Do LDL and HDL use the same conversion factor as total cholesterol?
Yes. Total cholesterol, LDL, and HDL all measure the same cholesterol molecule, so all three use the factor 38.67 (1 mmol/L = 38.67 mg/dL). Only triglycerides differ, using 88.57. So once you have converted your total cholesterol, you can reuse the same math for LDL and HDL — but never for triglycerides.
Can I convert my TC/HDL ratio or other lipid ratios between units?
No — ratios must be calculated from values already in the same unit system. A total cholesterol of 200 mg/dL and HDL of 50 mg/dL give a TC/HDL ratio of 4.0; in mmol/L the same readings (5.2 and 1.3) also give roughly 4.0. But if you divide a value in mg/dL by one in mmol/L, the ratio is meaningless. Convert both numbers first, then divide.
Can I convert non-HDL cholesterol with this tool?
Yes, indirectly. Non-HDL cholesterol is total cholesterol minus HDL, and both use the same conversion factor, so you can subtract either before or after converting. For example, total cholesterol 5.6 mmol/L minus HDL 1.3 mmol/L equals non-HDL 4.3 mmol/L ≈ 166 mg/dL. A non-HDL goal below 130 mg/dL (3.4 mmol/L) is often suggested for people at elevated cardiovascular risk.
Why do I sometimes see 88.6 or 39 instead of 88.57 and 38.67?
Different sources round the molecular weights differently. You may see 38.6, 38.7, or 39 for cholesterol and 88.5, 88.6, or 89 for triglycerides. The small differences change the result by well under 2%, which almost never affects your interpretation category. Any of these figures gives an essentially equivalent conversion for practical purposes.
Does fasting affect my lipid values, and does that change the conversion?
Fasting affects the measurement, not the conversion. Triglycerides rise noticeably after a meal, which is why guidelines suggest a 9–12 hour fast for the most reliable triglyceride reading; total and HDL cholesterol change little with fasting. The unit conversion itself is identical regardless of when the blood was drawn.
My converted value is just barely over a threshold — should I be worried?
A value that sits right on a category boundary, such as total cholesterol of 201 mg/dL (5.21 mmol/L), is not meaningfully different from one just below it. Categories are convenient screening bands, not sharp clinical lines. A single reading can also be influenced by recent illness, diet, or medication. Discuss borderline results with your doctor rather than adjusting treatment yourself.