Cholesterol Units Converter
Convert total cholesterol, LDL, HDL, and triglycerides between mg/dL and mmol/L in one step. See exactly where each number falls on standard reference ranges, get your TC/HDL ratio, and estimate LDL with the Friedewald formula if your lab report doesn't include it directly.
For total cholesterol, LDL, and HDL: mg/dL × 0.02586 = mmol/L (or mmol/L × 38.67 = mg/dL). For triglycerides, use a different factor: mg/dL × 0.01129 = mmol/L (or mmol/L × 88.57 = mg/dL). Example: 200 mg/dL total cholesterol = 5.17 mmol/L.
Why cholesterol has two different units in the first place
Cholesterol concentration in blood can be expressed two different ways: by mass per volume (milligrams per deciliter, mg/dL) or by molar amount per volume (millimoles per liter, mmol/L). The United States reports cholesterol in mg/dL, while most of Europe, Canada, Australia, and much of the rest of the world uses mmol/L as the standard SI unit. Neither is more "correct" — they're just two different measurement conventions — but the split means a lab report, a research paper, or an online reference range can show completely different-looking numbers for the exact same blood sample depending on which system it uses.
This becomes a real practical problem for anyone reading international health guidance, comparing lab results across countries, or just trying to understand a number that doesn't match what they're used to seeing. This calculator handles the conversion and tells you what the number actually means, in one step.
The conversion formulas
Total Cholesterol, LDL, HDL
mg/dL × 0.02586 = mmol/L
mmol/L × 38.67 = mg/dL
These three lipid measurements share a conversion factor because they're all expressed as cholesterol mass, just carried by different lipoprotein particles.
Triglycerides
mg/dL × 0.01129 = mmol/L
mmol/L × 88.57 = mg/dL
Triglycerides use a different factor because they're a structurally different molecule with a different molar mass than cholesterol.
Reference ranges, in both units
These are commonly used general population reference ranges. They're a useful starting point for understanding a lab result, but your own healthy target can differ based on age, existing heart disease risk, and other personal health factors — always interpret your results with a healthcare provider.
| Category | mg/dL | mmol/L | Classification |
|---|---|---|---|
| Total Cholesterol | < 200 | < 5.17 | Desirable |
| 200 - 239 | 5.17 - 6.18 | Borderline High | |
| ≥ 240 | ≥ 6.21 | High | |
| LDL | < 100 | < 2.59 | Optimal |
| 100 - 129 | 2.59 - 3.34 | Near / Above Optimal | |
| 130 - 189 | 3.36 - 4.89 | Borderline High / High | |
| ≥ 190 | ≥ 4.91 | Very High | |
| HDL | < 40 (men) / < 50 (women) | < 1.03 / < 1.29 | Low (risk factor) |
| ≥ 60 | ≥ 1.55 | Optimal (protective) | |
| Triglycerides | < 150 | < 1.69 | Normal |
| 150 - 199 | 1.69 - 2.25 | Borderline High | |
| ≥ 200 | ≥ 2.26 | High |
Don't have an LDL number? Here's how it's estimated
Some older or simpler lipid panels report total cholesterol, HDL, and triglycerides but not LDL directly. When that's the case, LDL is commonly estimated using the Friedewald formula:
LDL (mg/dL) = Total Cholesterol − HDL − (Triglycerides ÷ 5)
This works because triglycerides divided by 5 approximates the cholesterol carried by VLDL particles, which can then be subtracted out along with HDL to isolate the LDL portion. The formula becomes unreliable once triglycerides rise above roughly 400 mg/dL (4.52 mmol/L), since the underlying VLDL assumption breaks down at that point — this calculator will flag the estimate rather than show a misleading number if your triglycerides are in that range.
What actually influences these numbers
For many people, diet and body composition play a genuine role in LDL, HDL, and triglyceride levels, alongside genetics and other factors outside your control. Dietary fat — specifically the type of fat, not just the total amount — is one of the more directly studied influences on LDL specifically. If you're looking at your own eating pattern in relation to your numbers, our fat intake calculator breaks down a reasonable daily fat target based on your total calorie needs, which is a natural next step after seeing where your lipid panel actually stands.
Body weight and overall calorie balance are two other commonly discussed factors. Our calorie calculator and maintenance calorie calculator can help establish what your body actually needs day to day, while our ideal weight calculator gives a general reference range for a healthy weight given your height and frame. None of these replace a conversation with a healthcare provider about your specific results, but they're useful starting points for understanding the bigger picture your cholesterol numbers sit inside.
Cholesterol units converter — FAQ
How do I convert cholesterol from mg/dL to mmol/L?
For total cholesterol, LDL, and HDL, multiply the mg/dL value by 0.02586 to get mmol/L. For triglycerides, the conversion factor is different — multiply by 0.01129 instead. A total cholesterol reading of 200 mg/dL, for example, works out to 200 x 0.02586 = 5.17 mmol/L. Triglycerides use their own factor because they're a different type of molecule with a different molar mass than cholesterol, which is why one universal factor doesn't work for the whole lipid panel.
Why do some countries use mmol/L and others use mg/dL for cholesterol?
mg/dL (milligrams per deciliter) is the standard used in the United States, while mmol/L (millimoles per liter) is the SI unit used across most of Europe, Canada, Australia, and much of the rest of the world. Neither unit is more accurate than the other — they're just two different ways of expressing the same underlying concentration, one based on mass per volume and the other based on molar amount per volume. This split is exactly why lab reports, medical journals, and online cholesterol calculators can show numbers that look completely different for the identical blood sample.
What do "normal," "borderline," and "high" cholesterol numbers actually mean?
These labels come from widely used clinical reference ranges. For total cholesterol, under 200 mg/dL (5.17 mmol/L) is generally considered desirable, 200-239 mg/dL (5.17-6.18 mmol/L) borderline high, and 240 mg/dL (6.21 mmol/L) or above high. For LDL, under 100 mg/dL (2.59 mmol/L) is optimal, climbing through near-optimal, borderline high, high, and very high above 190 mg/dL (4.91 mmol/L). These are general population reference points, not personalized targets — your own healthy range can differ based on age, existing heart disease risk, and other health conditions, which is why a healthcare provider's interpretation matters more than the raw number alone.
Why does HDL have different "healthy" thresholds for men and women?
HDL is the one lipid measurement where biological sex genuinely shifts the reference range. An HDL below 40 mg/dL (1.03 mmol/L) is considered a risk factor for men, while the equivalent threshold for women is below 50 mg/dL (1.29 mmol/L) — women naturally tend to run higher HDL levels on average. For both sexes, 60 mg/dL (1.55 mmol/L) or above is generally considered protective against heart disease, since HDL helps clear excess cholesterol from the bloodstream rather than depositing it.
What's the Friedewald formula, and why does this calculator include it?
The Friedewald formula estimates LDL cholesterol when a lab report only provides total cholesterol, HDL, and triglycerides but not LDL directly — a common situation with older or simpler lipid panels. In mg/dL, it's LDL = Total Cholesterol - HDL - (Triglycerides / 5). The formula becomes unreliable once triglycerides climb above roughly 400 mg/dL (4.52 mmol/L), since the underlying assumption about how VLDL cholesterol relates to triglycerides starts to break down at that point, which is why this calculator flags the estimate as unreliable above that threshold rather than showing a misleading number.
Is a cholesterol ratio (like TC/HDL) more useful than the individual numbers?
Many clinicians consider the total cholesterol to HDL ratio a useful secondary indicator alongside the individual values, since it captures the balance between total lipid load and protective HDL rather than looking at either number in isolation. A ratio under 3.5 is generally considered optimal, while a ratio above 5 is often flagged as an increased risk indicator. That said, the ratio works alongside — not instead of — your individual LDL, HDL, and triglyceride numbers, since two people with identical ratios can still have very different absolute risk depending on where those individual numbers actually sit.
How often should cholesterol actually be checked?
General guidance from major health organizations suggests most adults have a lipid panel checked every four to six years starting around age 20, with more frequent testing recommended for anyone with risk factors like a family history of heart disease, existing high cholesterol, diabetes, or other cardiovascular risk factors. Your own healthcare provider is best positioned to recommend a testing frequency based on your personal and family health history rather than a one-size-fits-all interval.
Can diet and lifestyle actually change these numbers?
Yes, for many people diet, physical activity, weight, and other lifestyle factors meaningfully influence LDL, HDL, and triglyceride levels, though genetics also plays a real role and some people need medication regardless of lifestyle changes. Reducing saturated and trans fat intake, increasing physical activity, and maintaining a healthy weight are commonly cited strategies for improving a lipid panel, though the right combination of approaches depends on your individual numbers and overall health picture, which is a conversation worth having directly with a healthcare provider.
This calculator is for educational purposes only. It is not medical advice. Always consult a qualified doctor or health professional before making health decisions.
