Cholesterol mg/dL to mmol/L Converter

The short answer

To convert cholesterol from mg/dL to mmol/L, divide by 38.67 (or multiply by 0.02586). To convert mmol/L to mg/dL, multiply by 38.67. A total cholesterol of 200 mg/dL is 5.17 mmol/L, an LDL of 100 mg/dL is 2.59 mmol/L, and an HDL of 1.0 mmol/L is 39 mg/dL. The same factor works for total cholesterol, LDL cholesterol (LDL-C), HDL cholesterol (HDL-C), non-HDL cholesterol and remnant cholesterol – but not for triglycerides, which need their own factor of 88.57.

The tool above converts in both directions and shows the matching category from the US National Cholesterol Education Program (NCEP ATP III) classification. The rest of this guide explains where the factor comes from, how guideline targets translate between units, and what can make a cholesterol result misleading.

What a cholesterol test measures

Cholesterol is a waxy lipid that every cell uses to build membranes, steroid hormones, vitamin D and bile acids. Because it does not dissolve in blood, it travels inside lipoprotein particles. A standard lipid panel (lipid profile) usually reports:

• Total cholesterol – all the cholesterol carried in every lipoprotein.
• HDL cholesterol – the cholesterol in high-density lipoproteins, which carry cholesterol back to the liver. Higher levels are associated with lower cardiovascular risk at the population level.
• LDL cholesterol – the cholesterol in low-density lipoproteins, the main driver of atherosclerosis. Most labs calculate it rather than measure it; see our LDL calculator.
• Triglycerides – a different type of fat, reported alongside but converted with a different factor; see our triglycerides converter.
• Non-HDL cholesterol – total minus HDL, capturing all atherogenic particles; see our non-HDL calculator.

Some reports also include a total/HDL ratio, VLDL cholesterol, apolipoprotein B or lipoprotein(a). Apolipoprotein B and lipoprotein(a) are measured in different ways and cannot be converted with the cholesterol factor.

mg/dL and mmol/L explained

mg/dL expresses how many milligrams of cholesterol are present in a deciliter (100 mL) of serum. It is used in the United States, much of Latin America, Japan and some other countries.

mmol/L expresses how many millimoles of cholesterol molecules are present in a liter. It is the SI unit and is used in the UK, Europe, Canada, Australia, New Zealand, China and most of the world.

Where 38.67 comes from

Cholesterol (C₂₇H₄₆O) has a molar mass of 386.65 g/mol. One millimole weighs 386.65 mg, so 1 mmol/L is 386.65 mg per liter, or 38.67 mg per deciliter. Hence:

• mmol/L = mg/dL ÷ 38.67 = mg/dL × 0.02586
• mg/dL = mmol/L × 38.67

Some references round the factor to 38.6 or 39. Over the usual range of results this changes the converted value by at most a few hundredths of a mmol/L, which never changes a treatment category, but using 38.67 keeps you consistent with laboratory conversion tables.

How to convert step by step

1. Identify which value you are converting (total, LDL, HDL or non-HDL) and confirm it is not triglycerides.
2. mg/dL → mmol/L: divide by 38.67 and round to one or two decimals (UK and European reports usually show one decimal; some show two).
3. mmol/L → mg/dL: multiply by 38.67 and round to a whole number.
4. Compare with a threshold expressed in the same unit.

Worked examples

• Total cholesterol 236 mg/dL: 236 ÷ 38.67 = 6.10 → 6.1 mmol/L (borderline high).
• LDL 162 mg/dL: 162 ÷ 38.67 = 4.19 → 4.2 mmol/L (high).
• HDL 1.3 mmol/L: 1.3 × 38.67 = 50.3 → 50 mg/dL.
• Non-HDL 3.4 mmol/L: 3.4 × 38.67 = 131.5 → 131 mg/dL, just above the 130 mg/dL desirable limit.
• LDL goal of 1.8 mmol/L: 1.8 × 38.67 = 69.6 → 70 mg/dL, the classic target for people with established cardiovascular disease.

Cholesterol conversion chart

The left table converts common mg/dL values to mmol/L. The right table converts common mmol/L values back to mg/dL. Use it for total, LDL, HDL or non-HDL cholesterol.

Cholesterol levels by category

The categories below are the adult classification from the NCEP Adult Treatment Panel III, published by the US National Heart, Lung, and Blood Institute. They remain the most widely quoted descriptive cut-offs even though modern guidelines base treatment on overall risk rather than on a single number.

Many European and UK sources use "below 5 mmol/L" for total cholesterol and "below 3 mmol/L" for LDL as general population guides, and define low HDL as below 1.0 mmol/L in men and below 1.2 mmol/L in women.

Children and adolescents

For people under 20, the US expert panel on cardiovascular health in childhood uses lower cut-offs: total cholesterol is acceptable below 170 mg/dL (4.4 mmol/L), borderline at 170–199 mg/dL and high at 200 mg/dL (5.2 mmol/L) or more; LDL is acceptable below 110 mg/dL (2.8 mmol/L) and high at 130 mg/dL (3.4 mmol/L) or more.

Guideline targets in both units

Treatment targets differ between guidelines and are expressed in different units, which is exactly where conversion matters:

The European Society of Cardiology and European Atherosclerosis Society also recommend at least a 50% reduction from baseline for high- and very-high-risk patients. The American College of Cardiology/American Heart Association 2018 guideline uses percentage reductions and LDL thresholds rather than fixed targets. Your own target depends on your risk category, which only your clinician can determine.

How to prepare for a cholesterol test

Most people do not need special preparation. Current European and US guidance accepts a non-fasting sample for routine screening, because total cholesterol, HDL and non-HDL cholesterol are barely affected by a normal meal. Your clinician may still ask you to fast for 9–12 hours (water is fine) if a previous result showed high triglycerides, if you are being assessed for an inherited lipid disorder, or if the lab calculates LDL with an equation that is sensitive to triglycerides.

A few practical points make results more comparable over time:

• Keep to your usual diet and activity in the week before the test rather than making sudden changes.
• Avoid heavy alcohol intake in the 24–48 hours beforehand, as it mainly raises triglycerides.
• Take your regular medicines as usual unless told otherwise, and tell the clinician which lipid-lowering drugs you take and when you started them.
• If you have just had an infection, surgery or a heart attack, ask whether the test should be delayed – acute illness can lower cholesterol for several weeks.
• When comparing results, try to use the same laboratory, because methods and calculation formulas differ slightly between labs.

Tracking your cholesterol over time

Because cholesterol varies from one test to the next, look at the trend over several results rather than a single value. After starting or changing a statin, guidelines typically recommend a repeat lipid panel after 4–12 weeks to check the response, then every 3–12 months as needed. A good response to a moderate-intensity statin lowers LDL by roughly 30–49%, and a high-intensity statin by about 50% or more.

When results come from different countries, convert them all into one unit before plotting them. For example, an LDL of 4.1 mmol/L before treatment (159 mg/dL) and 78 mg/dL afterwards represents a fall of about 51% – easy to see once both are in the same unit, but impossible to judge if you compare 4.1 with 78 directly.

Cholesterol in children and young adults

Many guidelines recommend checking cholesterol at least once in childhood, usually between ages 9 and 11, and again between 17 and 21, with earlier testing if a parent has very high cholesterol or early heart disease. Reference points for children are lower than for adults. In US paediatric guidance, total cholesterol below 170 mg/dL (4.4 mmol/L) is considered acceptable, 170–199 mg/dL (4.4–5.1 mmol/L) borderline, and 200 mg/dL (5.2 mmol/L) or above high. For LDL, below 110 mg/dL (2.8 mmol/L) is acceptable and 130 mg/dL (3.4 mmol/L) or above is high. An LDL persistently above about 160 mg/dL (4.1 mmol/L) in a child, together with a family history of early heart disease, should prompt assessment for familial hypercholesterolemia, which affects roughly 1 in 250 people and is very treatable when found early.

Questions to ask your doctor about your cholesterol

• What is my LDL or non-HDL target, and which risk category am I in?
• Should my lipoprotein(a) be measured at least once? Many guidelines now recommend this, because it is largely inherited and not reflected in the standard panel.
• Is there any sign of an inherited condition such as familial hypercholesterolemia in me or my family?
• Could another condition, such as an underactive thyroid or kidney disease, be raising my cholesterol?
• How soon should I be retested, and should the test be fasting?

What affects cholesterol results

• Fasting. Total and HDL cholesterol change very little after a meal. Calculated LDL can drop slightly after eating because triglycerides rise. Non-fasting panels are acceptable for most people; fasting is preferred if triglycerides are very high.
• Recent illness. Acute infection, surgery or a heart attack can lower cholesterol temporarily. Guidelines suggest waiting several weeks after an acute illness for a representative result.
• Pregnancy raises cholesterol and triglycerides substantially, especially in the third trimester.
• Medications. Statins, ezetimibe and PCSK9 inhibitors lower LDL; some diuretics, beta-blockers, corticosteroids, retinoids, certain immunosuppressants and antiretroviral drugs can raise lipids.
• Other conditions. Hypothyroidism, nephrotic syndrome, cholestatic liver disease and poorly controlled diabetes can all raise cholesterol, which is why thyroid and kidney tests are often checked with a new high result.
• Biological variation. Total cholesterol varies by several percent from week to week in the same person, so small changes between tests may not be meaningful.

High and low cholesterol: what the numbers mean

A high LDL or non-HDL cholesterol increases the long-term risk of heart attack and stroke; the risk depends on how high the level is and for how long, plus other factors such as blood pressure, smoking, diabetes, age and family history. LDL of 190 mg/dL (4.9 mmol/L) or higher in an adult raises the possibility of familial hypercholesterolemia, an inherited condition that is underdiagnosed and important to identify because relatives may be affected.

Very low cholesterol is uncommon; on its own it is not usually harmful and is expected on intensive lipid-lowering therapy. Unexpectedly low levels can occasionally reflect malnutrition, hyperthyroidism, liver disease or rare inherited conditions.

Low HDL often accompanies high triglycerides, excess weight, inactivity and insulin resistance. Raising HDL with drugs has not been shown to reduce heart attacks, so treatment focuses on lowering LDL and non-HDL cholesterol.

When to see a doctor

Ask your doctor about a lipid test if you are an adult who has never had one, have a family history of early heart disease or high cholesterol, or have diabetes, high blood pressure, kidney disease or a history of smoking. Discuss your result promptly if LDL is 190 mg/dL (4.9 mmol/L) or more, total cholesterol is above 310 mg/dL (8 mmol/L), or triglycerides are very high, because these levels can point to inherited lipid disorders. If you have chest pain, breathlessness on exertion or stroke symptoms, seek medical care immediately regardless of your cholesterol result.