LDL Cholesterol Calculator (Friedewald Equation)
Estimate LDL-C from a standard lipid panel using the Friedewald formula. Supports mg/dL and mmol/L, with automatic interpretation.
Educational tool only – does not provide medical diagnosis or treatment. Always discuss your results with a healthcare professional.
LDL calculator
Tip
Check your lab report to see whether values are reported in mg/dL or mmol/L before entering them.
How this LDL cholesterol calculator works
This tool estimates low-density lipoprotein cholesterol (LDL-C, often called “bad cholesterol”) using the Friedewald equation. It uses three values from a standard fasting lipid panel: total cholesterol, HDL cholesterol, and triglycerides.
Friedewald equation (mg/dL)
\( \text{LDL-C} = \text{Total Cholesterol} - \text{HDL-C} - \dfrac{\text{Triglycerides}}{5} \)
Friedewald equation (mmol/L)
\( \text{LDL-C} = \text{Total Cholesterol} - \text{HDL-C} - \dfrac{\text{Triglycerides}}{2.2} \)
The term Triglycerides / 5 (or
/ 2.2 in mmol/L) is an estimate of
VLDL cholesterol (very-low-density
lipoprotein), so the formula effectively does:
LDL-C ≈ Total cholesterol − HDL-C − VLDL-C
When is the Friedewald formula valid?
- Sample should be fasting (typically 9–12 hours).
- Triglycerides should be below 400 mg/dL (4.5 mmol/L).
- No extreme lipid disorders (e.g., type III hyperlipoproteinemia).
If these conditions are not met, laboratories often use a direct LDL measurement or alternative formulas. This calculator will warn you when triglycerides are in a range where the Friedewald equation may be unreliable.
LDL cholesterol categories
Different guidelines use slightly different cut-offs, but a commonly used classification for adults is:
| Category | LDL (mg/dL) | LDL (mmol/L) |
|---|---|---|
| Optimal | < 100 | < 2.6 |
| Near optimal / above optimal | 100–129 | 2.6–3.3 |
| Borderline high | 130–159 | 3.4–4.1 |
| High | 160–189 | 4.1–4.9 |
| Very high | ≥ 190 | ≥ 4.9 |
Note: Targets may be lower for people with existing cardiovascular disease, diabetes, chronic kidney disease, or very high overall risk. Always follow your clinician’s individualized targets.
How to use the LDL calculator step by step
- Get a recent fasting lipid panel from your lab report.
- Check whether the results are in mg/dL or mmol/L and select the same unit.
- Enter your total cholesterol, HDL cholesterol, and triglycerides.
- Click “Calculate LDL”.
- Review the estimated LDL-C value and the category shown.
- Discuss the result with your doctor, especially if LDL is elevated or if you have other risk factors.
Limitations and clinical caveats
- The Friedewald equation is an estimate, not a direct measurement.
- It may underestimate LDL in people with very high triglycerides or certain metabolic conditions.
- For people on potent lipid-lowering therapy with very low LDL, more precise methods may be preferred.
- Cardiovascular risk depends on many factors (age, blood pressure, smoking, diabetes, family history), not LDL alone.
This calculator is intended for education and general information. It is not a substitute for professional medical advice, diagnosis, or treatment.
LDL cholesterol calculator – FAQ
Is fasting required for an accurate LDL estimate?
The Friedewald equation was developed for fasting samples, because eating can temporarily raise triglycerides and affect the VLDL estimate. Many labs now offer non-fasting lipid profiles, but if triglycerides are high, your clinician may repeat the test fasting or use a direct LDL measurement.
What if my triglycerides are very high?
When triglycerides are ≥ 400 mg/dL (4.5 mmol/L), the Friedewald formula is generally considered unreliable. In that case, guidelines recommend a direct LDL-C assay or alternative formulas. This calculator will flag high triglyceride values, but it cannot replace lab methods.
Can lifestyle changes improve LDL cholesterol?
Many people can lower LDL-C through a combination of:
- Dietary changes (less saturated and trans fat, more fiber, fruits, and vegetables)
- Regular physical activity
- Weight management if overweight
- Not smoking and moderating alcohol intake
However, some people also need medication (e.g., statins, ezetimibe, PCSK9 inhibitors). Only your clinician can advise what is appropriate for you.
Should I change or stop my medication based on this calculator?
No. Never start, stop, or change any medication based on an online calculator. Use this tool only as a supplement to the information provided by your healthcare team, and always consult them before making treatment decisions.