A cholesterol unit converter exists because two countries can report the same blood sample as "200" and as "5.17" and both be correct. One is a mass concentration — milligrams of substance in a decilitre of blood. The other is a molar concentration — millimoles of substance in a litre. Converting between them requires the molecular weight of the substance being measured, which is why a lipid panel needs two different factors rather than one.
Arb Digital publishes a free tools library covering practical conversions, and this page does exactly one job: it changes the units on numbers you already have. It does not interpret them. This page sits alongside the blood sugar converter, which handles glucose and uses a different factor again, and the general-purpose concentration converter for laboratory work outside clinical panels.
What This Cholesterol Unit Converter Does
It takes four values from a lipid panel — total cholesterol, LDL, HDL and triglycerides — and converts all four in one pass, in either direction. It applies the cholesterol factor to the first three and the triglyceride factor to the fourth, because those are different substances with different molecular weights.
It also reports non-HDL cholesterol, which is total cholesterol minus HDL. That is a subtraction, and the subtraction gives the same answer whichever unit you do it in, so it appears in the converted units alongside everything else.
What it does not do is tell you what any of those numbers mean. There are no target ranges on this page, no colour coding and no commentary on whether a value is high or low. Reference ranges differ between laboratories and between clinical guidelines, and interpreting a lipid panel — in the context of everything else known about a person — is the job of a doctor or another qualified clinician, not of a converter.
How to Use It
- Choose the direction first. Everything below it is read in the source unit, so switching direction after typing changes what your numbers mean.
- Enter the four values exactly as your report shows them. Do not round first; rounding before converting compounds the error.
- Leave the factors alone unless you have a reason. They are editable so that anyone following a specific standard can match it exactly, not because the defaults need changing.
- Set the decimal places to match reporting convention. mmol/L results are normally shown to two decimals, mg/dL results to none.
- Keep the original alongside the conversion. When a result is shared with a clinician, the measured value and its unit matter more than a converted copy of it.
The Formula / How It's Calculated
Both directions are a single operation. mmol/L = mg/dL ÷ factor, and mg/dL = mmol/L × factor. The factor is 38.67 for total, LDL and HDL cholesterol, and 88.57 for triglycerides. Both are published in the Lipid Conversion Factors appendix of an AHRQ comparative effectiveness review hosted on the NCBI Bookshelf, which states directly that cholesterol is converted by multiplying mmol/L by 38.67 or dividing mg/dL by 38.67, and triglycerides by 88.57.
Worked example with the values the page loads with, converting mg/dL to mmol/L. Total cholesterol 200 ÷ 38.67 = 5.17 mmol/L. LDL 120 ÷ 38.67 = 3.10. HDL 50 ÷ 38.67 = 1.29. Triglycerides 150 ÷ 88.57 = 1.69. Non-HDL is 200 − 50 = 150 mg/dL, which is 3.88 mmol/L.
Reversing the direction returns the original values, subject to the decimal places you kept. Converting 5.17 back gives 199.9, not exactly 200, which is a rounding artefact rather than an error — and a good illustration of why the original measurement should always be the one that travels.
Why Cholesterol and Triglycerides Need Different Factors
A molar concentration counts particles; a mass concentration weighs them. Converting between the two requires knowing how much one mole of the substance weighs, so any substance with a different molecular weight has a different factor.
Cholesterol is a single, well-defined molecule with a molecular weight of about 386.65 grams per mole. Working the units through — milligrams per decilitre to millimoles per litre involves a factor of ten for the volume and a thousand for the mass — produces the 38.67 figure. That is why total, LDL and HDL all share it: all three measure the mass of cholesterol carried in different lipoprotein fractions, and it is the same molecule in each case.
Triglycerides are not one molecule. A triglyceride is a glycerol backbone with three fatty acids attached, and which fatty acids they are varies from sample to sample. The 88.57 factor comes from an assumed average molecular weight of roughly 885 grams per mole, based on a typical fatty acid mix. This has a consequence worth stating plainly: the triglyceride conversion is an approximation in a way the cholesterol conversion is not. It is standard, it is universally used, and it is still an assumption about composition.
The size difference is why using the wrong factor is so visible. Applying 38.67 to a triglyceride value produces a number 2.29 times too large. If a converted triglyceride figure looks strikingly out of line with the rest of a panel, a mixed-up factor is the first thing to check. The molar mass calculator shows where figures like these come from for any compound.
Which Unit Does Which Country Use?
The United States reports lipids in mg/dL. Most of Europe, Canada, Australia and much of Asia report in mmol/L, following the International System of Units, in which the mole is the base unit for amount of substance — the framework documented by the National Institute of Standards and Technology's SI Units pages.
This matters for anyone comparing results across borders: moving between countries, reading research published elsewhere, or using an app whose defaults do not match the local laboratory. Published guidelines quote thresholds in the units of the country that wrote them, and comparing a value in one unit against a threshold in another is a serious mistake — the numbers differ by nearly forty-fold, so it is usually obvious, but not always when only one figure is on screen.
A related trap is the unit abbreviations themselves. mmol/L and mol/L differ by a factor of a thousand, and mg/dL and mg/L by a factor of ten. Copying a value without its unit is how those errors get in. Use the unit converter for general SI prefix work.
Precision, Rounding and What Survives a Conversion
A converted number cannot be more accurate than the measurement it came from. If a laboratory reports total cholesterol as 200 mg/dL, the true value lies somewhere in a band around 200, and dividing by 38.67 does not narrow that band — it just relabels it. Reporting 5.1719 mmol/L implies a precision the assay does not have.
Two decimal places is the normal convention for mmol/L and none for mg/dL, which is why the decimal places field defaults to two. Set it higher only if you are checking arithmetic, never for recording a result.
Do not round before converting, either. Rounding 200.4 to 200 and then converting is not the same as converting first, and while the difference is small for a single value it accumulates across a panel and across a series of results tracked over time. If you are following a series, the percentage change calculator will quantify movement between two readings — but do that in one consistent unit rather than converting each reading separately.
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Browse Free Tools Talk to Arb DigitalCommon Mistakes to Avoid
- Using 38.67 for triglycerides — triglycerides use 88.57, and applying the cholesterol factor overstates the result by a factor of 2.29.
- Switching direction after entering values — the inputs are always read in the source unit, so changing direction reinterprets everything you typed.
- Comparing a value in one unit against a threshold quoted in another — guidelines state thresholds in their own country's unit, and mixing the two is meaningless.
- Rounding before converting — do the conversion on the reported figure, then round the result, not the other way round.
- Treating a converted number as a new measurement — the original value and its unit are what a clinician needs; a conversion is a convenience, not a result.
Related Free Tools From Arb Digital
The blood sugar converter handles glucose, which uses its own factor, and the concentration converter covers general laboratory concentration units. For the chemistry behind the factors, see the molar mass calculator and the molarity calculator, and for everyday SI work the unit converter. Everything else is in the free online tools hub.
Frequently Asked Questions
38.67. Multiply mmol/L by 38.67 to get mg/dL, or divide mg/dL by 38.67 to get mmol/L. The same factor applies to total, LDL and HDL cholesterol, because all three measure the same molecule carried in different lipoprotein fractions.
Because a triglyceride molecule is much heavier than a cholesterol molecule. Cholesterol has a molecular weight of about 386.65 grams per mole, while triglycerides average roughly 885. Converting between mass and molar concentration depends on molecular weight, so the two substances need different factors.
No, and this is worth knowing. Triglycerides are a family of molecules whose weight depends on which fatty acids are attached, so 88.57 reflects an assumed average composition. It is the standard factor and universally used, but it rests on an assumption in a way the cholesterol factor does not.
It is total cholesterol minus HDL cholesterol. Because it is a subtraction of two values in the same unit, it gives the same answer whichever unit you do it in, and it converts with the ordinary cholesterol factor.
The United States reports lipids in mg/dL. Most of Europe, Canada, Australia and much of Asia use mmol/L, following the International System of Units in which the mole is the base unit for amount of substance. Guidelines quote their thresholds in their own country's unit.
Two for mmol/L and none for mg/dL matches normal laboratory reporting. A conversion cannot be more precise than the assay that produced the original number, so extra decimal places imply an accuracy that is not there.
No. It converts units and nothing else. There are no reference ranges on this page because they differ between laboratories and guidelines, and because a lipid panel is interpreted in the context of everything else known about a person — which is a job for a doctor or other qualified clinician.
This tool converts units of measurement and does not interpret results. It is not medical advice, contains no reference ranges, and no decision about health, medication or treatment should be based on it. Discuss any blood test result with a doctor or other qualified clinician, who is the person able to interpret it.
