LDL Cholesterol Calculator (NIH and Friedewald)

How it is calculated

NIH (Sampson) equation: LDL = TC/0.948 − HDL/0.971 − (TG/8.56 + TG × non-HDL/2140 − TG²/16100) − 9.44, in mg/dL. Friedewald: LDL = TC − HDL − TG/5.

What your result means

• Calculated LDL depends on all three inputs, so a lab error in triglycerides changes the result.
• Above 400 mg/dL triglycerides the Friedewald estimate is unreliable, and above 800 mg/dL a direct LDL test is needed.
• Your own lab's printed range and your clinician's read of your history come first; this calculator is educational and is not a diagnosis.

Test the inputs

The Heart health panel measures the values this calculator uses. Related: ldl cholesterol, hdl cholesterol, triglycerides.

Common questions

Why is LDL calculated instead of measured?

Calculation from a standard lipid panel is cheaper and accurate for most people; a direct LDL test is used when triglycerides are very high.

What is the difference between the NIH and Friedewald equations?

Friedewald estimates the cholesterol carried by triglyceride-rich particles as triglycerides divided by 5. The NIH equation adjusts that estimate across a wider range of triglycerides.

Do I need to fast?

Friedewald was developed on fasting samples. Follow your lab's instructions for the panel you are ordering.

References

1. A New Equation for Calculation of Low-Density Lipoprotein Cholesterol in Patients With Normolipidemia and/or Hypertriglyceridemia. JAMA Cardiol, 2020.
2. Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge. Clin Chem, 1972.