LDL Cholesterol Unit Converter

Q: How do I convert LDL cholesterol from mg/dL to mmol/L?

Multiply by 0.0259, or divide by 38.67. An LDL-C of 128 mg/dL is 3.31 mmol/L, 100 mg/dL is 2.59 and 70 mg/dL is 1.81. The factor comes from cholesterol's molar mass of 386.65 and is the same for total, HDL and non-HDL cholesterol.

Q: What is a normal LDL cholesterol?

LDL-C does not have a reference interval in the usual sense, and that is not a technicality. Risk rises continuously with LDL-C and keeps falling as it is lowered well below any population's normal range, so the numbers quoted are treatment targets chosen for a risk category: below 55 mg/dL (1.4 mmol/L) at very high risk, below 70 (1.8) at high risk, below 100 (2.6) at moderate risk and below 116 (3.0) at low risk.

Q: Is the LDL cholesterol on my report measured or calculated?

On most reports it is calculated, usually by the Friedewald equation from total cholesterol, HDL and triglycerides, and the method is rarely printed. That estimate is invalid at a triglyceride of 400 mg/dL or above and underestimates LDL-C below about 70 mg/dL. The Sampson-NIH equation is better at both extremes, and a direct assay is a measurement rather than an estimate.

Q: What is 100 mg/dL of LDL in mmol/L?

2.59 mmol/L. That is the ESC/EAS goal for moderate cardiovascular risk, which the guideline prints as below 2.6 mmol/L or below 100 mg/dL — its two figures being mutual roundings rather than exact conversions of each other.

Q: Does LDL cholesterol use the same conversion factor as triglycerides?

No, and it is the commonest error on a lipid panel. Cholesterol is 386.65 g/mol and gives 0.0259; triglyceride is conventionally taken as 885.45 and gives 0.0113. Converting a triglyceride of 150 mg/dL with the cholesterol factor gives 3.9 mmol/L instead of the correct 1.7.

Q: Why do European and American targets use different numbers?

Partly units and partly framework. European guidance states goals in mmol/L with mg/dL in brackets and organises them by risk category; the American guideline works in mg/dL, leans on percentage reduction with a high-intensity statin, and uses thresholds such as 190 mg/dL for immediate treatment and 70 mg/dL for adding non-statin therapy after an event. The underlying evidence is largely shared.

Convert LDL cholesterol between mg/dL, mmol/L, mg/L and g/L — and read the answer against a treatment target rather than a reference interval, because LDL-C does not have one. The target depends on cardiovascular risk, and on most reports the LDL-C itself is a calculated number rather than a measured one.

Last updated 17 Sep 2026

LDL cholesterol converter

mg/dL ⇄ mmol/L

LDL cholesterol

mg/dL × 0.0258632 = mmol/L. The same factor converts total, HDL and non-HDL cholesterol, because all of them are cholesterol. It does not convert a triglyceride.

Read against the goal forThese are the 2019 ESC/EAS treatment goals, kept unchanged by the 2025 focused update. They are TARGETS, not reference limits: the risk category is decided clinically before the LDL-C is read, and at high and very high risk the guideline also requires at least a 50% reduction from baseline, which a converter cannot check. The figures stored here are the guideline’s own mg/dL goals; see the table for its mmol/L figures, which are rounded and differ slightly.

3.31mmol/LExample

LDL cholesterol 128 mg/dL, read against the very-high-risk goal

Formula and conversion factor

mmol/L = mg/dL × 0.0258632
mg/dL = mmol/L × 38.665
because 1 mg/dL is 0.01 g/L, and 0.01 ÷ 386.65 g/mol = 2.58632 × 10⁻⁵ mol/L

0.0258632: derived from the molar mass of cholesterol, 386.65 g/mol (C₂₇H₄₆O). Nothing about LDL enters into it — the factor is a property of the molecule, not of the particle carrying it
same factor as total and HDL: LDL-C, HDL-C, total cholesterol and non-HDL cholesterol are all cholesterol mass, so all four share this factor. There is no separate LDL conversion to remember
not triglycerides: a triglyceride on the same report needs 0.011294, from an assumed mass of 885.45. Using the cholesterol factor on a triglyceride overstates it by more than twofold
the mental check: mmol/L is roughly the mg/dL figure divided by 40. The pairs worth memorising are 55 mg/dL ≈ 1.4, 70 ≈ 1.8, 100 ≈ 2.6 and 190 ≈ 4.9 mmol/L
38.665, not 38.67: the exact reciprocal of 0.0258632. The rounding is immaterial clinically and is stated here only because the guideline thresholds are themselves rounded in both directions — see the first table

Worked example

LDL cholesterol 128 mg/dL, read against the very-high-risk goal
128 × 0.0258632 = 3.31 mmol/L
= 1,280 mg/L = 1.280 g/L
Against the goals: above the very-high-risk goal of 55 mg/dL (1.42 mmol/L) by more than twofold, above high risk at 70 (1.81), above moderate risk at 100 (2.59) and above low risk at 116 (3.00)
And on the older ATP III scale it is merely near optimal, in the 100–129 mg/dL band. One number, five verdicts, and the risk category is what decides which one applies

ESC/EAS goals in both units — including the rounding that changes verdicts

The guideline’s two figures in each row are mutual roundings, not exact conversions, and the gap is large enough to matter at the edge: 1.4 mmol/L is 54.1 mg/dL, so an LDL-C of 54.5 mg/dL is at goal on the mg/dL figure and above goal on the mmol/L one. Use whichever unit your own guideline and laboratory work in, and do not convert a threshold across units and then argue about the second decimal place. The 2025 focused update kept all four goals and changed the risk stratification to SCORE2 and SCORE2-OP.
Risk category	As the guideline prints it	Exact conversion of its mg/dL figure	Also required
Very high	< 1.4 mmol/L (< 55 mg/dL)	55 mg/dL = 1.42 mmol/L	At least a 50% reduction from baseline
High	< 1.8 mmol/L (< 70 mg/dL)	70 mg/dL = 1.81 mmol/L	At least a 50% reduction from baseline
Moderate	< 2.6 mmol/L (< 100 mg/dL)	100 mg/dL = 2.59 mmol/L	—
Low	< 3.0 mmol/L (< 116 mg/dL)	116 mg/dL = 3.00 mmol/L	—

A target is not a reference interval

Not one row here is a reference interval in the laboratory sense — the 2.5th to 97.5th centiles of a healthy population. There is no LDL-C at which risk begins: the relationship with cardiovascular events is continuous and runs well below any value a population survey would call normal. The site makes the same point on its apolipoprotein B page, where the population interval lies entirely above every treatment target. Read an LDL-C against a target chosen for the patient’s risk, not against a range printed beside it.
	mg/dL	mmol/L	What kind of statement it is
ESC/EAS goal, very high risk	< 55	< 1.4	A treatment target for a risk category
ESC/EAS goal, high risk	< 70	< 1.8	A treatment target for a risk category
ATP III: optimal	< 100	< 2.6	A population classification, not a reference interval
ATP III: near or above optimal	100 – 129	2.6 – 3.3	A population classification
ATP III: borderline high	130 – 159	3.4 – 4.1	A population classification
ATP III: high	160 – 189	4.1 – 4.9	A population classification
ATP III: very high	≥ 190	≥ 4.9	A threshold for immediate high-intensity statin treatment, whatever the risk score

How the LDL-C on your report was obtained

Most LDL-C results on most reports are calculated, not measured, and the equation used is rarely printed. That matters for this page in one specific way: the unit conversion is exact to as many decimal places as you like, and the input it is applied to may carry several mg/dL of estimation error. Converting a number does not make it more certain than it was.
Method	What it is	When it fails	Page
Friedewald equation	Total cholesterol − HDL − triglyceride/5 in mg/dL, or /2.2 in mmol/L	Invalid at a triglyceride of 400 mg/dL or above, and it increasingly underestimates as LDL-C falls below about 70 mg/dL — exactly where the targets now are	Friedewald calculator
Sampson-NIH equation	A better VLDL term, derived against beta-quantification	Validated to a triglyceride of 800 mg/dL; above that, request a direct LDL	Sampson-NIH calculator
Direct (homogeneous) assay	A measurement rather than an estimate	Methods differ between manufacturers and are not interchangeable for serial monitoring	—
Non-HDL cholesterol	Total cholesterol − HDL. No VLDL assumption and no fasting sample	Nothing much — which is why it is often the better number when triglycerides are raised	non-HDL cholesterol calculator
Apolipoprotein B	A count of atherogenic particles rather than the cholesterol in them	Needs its own assay, and its targets are different numbers	apolipoprotein B converter

A calculated number, read against a target that is not a normal range

The conversion itself is the cholesterol conversion, and there is nothing LDL-specific about it. LDL cholesterol is a measurement of cholesterol mass; so are total, HDL and non-HDL cholesterol. All four use the factor that falls out of cholesterol’s molar mass of 386.65 g/mol: one mg/dL is 0.01 g/L, and 0.01 divided by 386.65 is 2.58632 × 10⁻⁵ mol/L, so mg/dL × 0.0258632 gives mmol/L and the reciprocal, 38.665, goes back. The lipoprotein carrying the cholesterol does not change the molecule being weighed. The one thing not to do is carry this factor across to the triglyceride on the same report, which is a much heavier molecule and needs 0.011294 — an error of more than twofold, and the commonest conversion mistake on a lipid panel.

Two things about an LDL-C result matter more than its units, and the first is that it is usually not a measurement. On most reports in most countries LDL-C is calculated from the other three lipids, classically by the Friedewald equation: total cholesterol minus HDL minus an estimate of VLDL cholesterol taken as the triglyceride divided by five in mg/dL, or by 2.2 in mmol/L. That estimate is an assumption about the cholesterol-to-triglyceride ratio in VLDL, and it breaks in two directions that both matter now. It is invalid once the triglyceride reaches 400 mg/dL, and it increasingly underestimates LDL-C as the value falls below about 70 mg/dL — which is precisely the region the current targets occupy. The Sampson-NIH equation was derived against beta-quantification to fix both problems and is usable to a triglyceride of 800 mg/dL. When triglycerides are raised, non-HDL cholesterol needs no assumption at all, and apolipoprotein B counts particles rather than the cholesterol inside them. A converted LDL-C is only as good as the estimate it came from.

The second is that LDL cholesterol has no reference interval, and a report that prints one is being misleading. A laboratory reference interval describes what a healthy population has — the middle 95% of it — and for LDL-C that description has no bearing on what is safe, because the relationship between LDL cholesterol and atherosclerotic events is continuous and extends well below the range any Western population sits in. So the numbers that appear beside an LDL-C are treatment targets, chosen for a patient rather than derived from a population. The 2019 ESC/EAS guidelines, whose goals the 2025 focused update explicitly left unchanged, set them by risk category: below 1.4 mmol/L (55 mg/dL) at very high risk, below 1.8 (70) at high risk, below 2.6 (100) at moderate risk and below 3.0 (116) at low risk. At high and very high risk the guideline asks for at least a 50% reduction from baseline as well as the absolute goal, which is a requirement no unit converter can check, because it needs the untreated value.

The American framework is built differently and arrives at similar places. The 2018 AHA/ACC multisociety guideline treats an untreated LDL-C of 190 mg/dL or more as sufficient on its own for high-intensity statin therapy without a risk calculation, uses a 10-year risk of 7.5% to 19.9% as the band in which risk-enhancing factors decide, expects a high-intensity statin to lower LDL-C by 50% or more, and sets an LDL-C threshold of less than 70 mg/dL for adding non-statin therapy in very high-risk established disease. Older ATP III labels — optimal, near optimal, borderline high, high, very high — still appear on reports and in the calculators on this site, and they are population classifications rather than reference intervals or targets. If you take one thing from this page besides the factor: convert the number here, then decide the risk category, and only then decide whether the number is high.

Frequently asked questions

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

Multiply by 0.0259, or divide by 38.67. An LDL-C of 128 mg/dL is 3.31 mmol/L, 100 mg/dL is 2.59 and 70 mg/dL is 1.81. The factor comes from cholesterol’s molar mass of 386.65 and is the same for total, HDL and non-HDL cholesterol.

What is a normal LDL cholesterol?

LDL-C does not have a reference interval in the usual sense, and that is not a technicality. Risk rises continuously with LDL-C and keeps falling as it is lowered well below any population’s normal range, so the numbers quoted are treatment targets chosen for a risk category: below 55 mg/dL (1.4 mmol/L) at very high risk, below 70 (1.8) at high risk, below 100 (2.6) at moderate risk and below 116 (3.0) at low risk.

Is the LDL cholesterol on my report measured or calculated?

On most reports it is calculated, usually by the Friedewald equation from total cholesterol, HDL and triglycerides, and the method is rarely printed. That estimate is invalid at a triglyceride of 400 mg/dL or above and underestimates LDL-C below about 70 mg/dL. The Sampson-NIH equation is better at both extremes, and a direct assay is a measurement rather than an estimate.

What is 100 mg/dL of LDL in mmol/L?

2.59 mmol/L. That is the ESC/EAS goal for moderate cardiovascular risk, which the guideline prints as below 2.6 mmol/L or below 100 mg/dL — its two figures being mutual roundings rather than exact conversions of each other.

Does LDL cholesterol use the same conversion factor as triglycerides?

No, and it is the commonest error on a lipid panel. Cholesterol is 386.65 g/mol and gives 0.0259; triglyceride is conventionally taken as 885.45 and gives 0.0113. Converting a triglyceride of 150 mg/dL with the cholesterol factor gives 3.9 mmol/L instead of the correct 1.7.

Why do European and American targets use different numbers?

Partly units and partly framework. European guidance states goals in mmol/L with mg/dL in brackets and organises them by risk category; the American guideline works in mg/dL, leans on percentage reduction with a high-intensity statin, and uses thresholds such as 190 mg/dL for immediate treatment and 70 mg/dL for adding non-statin therapy after an event. The underlying evidence is largely shared.

Related calculators

References

Mach F, Baigent C, Catapano AL, et al. 2019 ESC/EAS Guidelines for the management of dyslipidaemias: lipid modification to reduce cardiovascular risk. Eur Heart J. 2020;41(1):111–188. Goals read from the guideline PDF published by the European Atherosclerosis Society and confirmed against the American College of Cardiology’s summary.
2025 Focused Update of the 2019 ESC/EAS Guidelines for the management of dyslipidaemias. Eur Heart J. 2025;46(42):4359. States that the LDL-C treatment goals for each risk category have not changed from 2019; risk stratification moves to SCORE2 and SCORE2-OP.
Grundy SM, Stone NJ, Bailey AL, et al. 2018 AHA/ACC multisociety guideline on the management of blood cholesterol. Circulation. 2019;139(25):e1082–e1143. The thresholds quoted here are taken from the American Heart Association’s own published highlights of that guideline.
Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults. Third Report of the National Cholesterol Education Program (NCEP) Expert Panel (Adult Treatment Panel III) final report. Circulation. 2002;106(25):3143–3421.
Friedewald WT, Levy RI, Fredrickson DS. Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge. Clin Chem. 1972;18(6):499–502.
Sampson M, Ling C, Sun Q, et al. A new equation for calculation of low-density lipoprotein cholesterol in patients with normolipidemia and/or hypertriglyceridemia. JAMA Cardiol. 2020;5(5):540–548.

Medical Disclaimer: The tools and content provided here are for educational and reference purposes only. They are not intended to substitute for professional medical advice, diagnosis, or treatment. Clinical decisions should always be based on the comprehensive assessment of a qualified healthcare professional.