What Is LDL Cholesterol?
LDL stands for low-density lipoprotein. It is a particle that carries cholesterol through your bloodstream. Because high levels of LDL cholesterol (LDL-C) are associated with an increased risk of atherosclerosis — the buildup of plaque in arteries — it is often called "bad cholesterol."
LDL-C is typically measured as part of a standard lipid panel. The result can be reported in two units:
- mg/dL (milligrams per deciliter) — commonly used in the United States.
- mmol/L (millimoles per liter) — commonly used in Europe, Canada, and many other countries.
The accepted conversion factor for cholesterol (including LDL-C) is 1 mmol/L = 38.67 mg/dL. This converter uses that exact relationship.
Why Does LDL Cholesterol Matter?
Numerous large-scale studies have shown that higher LDL-C levels are associated with a greater risk of cardiovascular events, including heart attack and stroke. Lowering LDL-C with evidence-based therapies — when clinically appropriate — has been shown to reduce that risk in specific patient populations.
However, LDL-C is just one piece of a much larger picture. Two people with the same LDL-C value may have very different overall cardiovascular risk depending on other factors.
Why Statin Decisions Depend on More Than LDL-C Alone
Clinical guidelines from major cardiology organizations — including the American Heart Association (AHA) and American College of Cardiology (ACC) — emphasize that the decision to start statin therapy is based on a comprehensive assessment of cardiovascular risk, not a single LDL-C number.
Key factors that inform that assessment include:
- Clinical ASCVD status: Whether you have already had a heart attack, stroke, or other atherosclerotic cardiovascular disease event.
- Diabetes: Diabetes significantly increases cardiovascular risk and influences treatment thresholds.
- 10-year ASCVD risk: For many adults without clinical ASCVD or diabetes, guidelines recommend estimating 10-year risk using validated equations (such as the Pooled Cohort Equations).
- Risk-enhancing factors: These include persistently elevated LDL-C (e.g., ≥160 mg/dL), metabolic syndrome, chronic kidney disease, inflammatory conditions, and elevated lipoprotein(a), among others.
- Coronary artery calcium (CAC) score: In some intermediate-risk patients, a CAC score can help clarify whether statin therapy is likely to be beneficial.
Because of this complexity, no calculator — including this one — can determine whether you personally need statin therapy. That determination requires a comprehensive evaluation by a qualified healthcare professional who can integrate your full medical history, risk factors, and preferences.
LDL-C Units and Conversion
If your lab report uses mmol/L but your doctor's reference range is in mg/dL (or vice versa), converting the value can help you understand where you stand. This tool performs that conversion instantly and accurately, using the standard cholesterol conversion factor.
Note: The conversion factor for cholesterol (38.67) differs from the factor for triglycerides (88.57). This tool applies the correct cholesterol-specific factor to LDL-C.
The Importance of Professional Assessment
Cardiovascular risk assessment and treatment decisions should always be made in partnership with a qualified healthcare professional. If you have questions about your LDL-C level, your overall cardiovascular risk, or whether any medication is appropriate for you, please discuss them with your doctor or another licensed clinician.
This page is designed to support — not replace — that conversation.