This calculator for estimating LDL cholesterol is based on the Friedewald equation. Enter lipid values in either mg/dL or mmol/L to calculate low-density cholesterol (LDL).

The Friedewald equation in mg/dL

LDL cholesterol calculator (#18)

The Friedewald equation in mmol/L units.

LDL cholesterol calculator (#19)


Routine lipid panels measure direct total cholesterol, HDL cholesterol, and triglycerides. LDL cholesterol is, however, estimated indirectly using the Friedewald equation. This equation was developed in 1972 using samples from just 448 subjects. Interestingly, the equation has gained wide acceptance in clinical medicine for several decades.


Lipid panel should be ordered after an overnight fast. In addition, the Friedewald equation performs poorly as an estimate of LDL cholesterol for patients with significant hypertriglyceridemia or very low LDL cholesterol. In this scenario, direct LDL cholesterol estimation by beta quantification is recommended.

Other equations have been recently reported in the literature. For example, the Martin-Hopkins equation is accurate for LDL cholesterol levels below 70mg/dL. On the other hand, the National Institutes of Health equation (by Sampson et al.) is most accurate in the setting of triglyceride levels above 400mg/dL.


  • Friedewald WT, Levy RI, Fredrickson DS. Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge. Clin Chem 1972;18:499-502.
  • Martin SS, Blaha MJ, Elshazly MB, et al. Comparison of a novel method vs the Friedewald equation for estimating low-density lipoprotein cholesterol levels from the standard lipid profile. JAMA 2013;310:2061-68.
  • Sampson M, Ling C, Sun Q et al. A new equation for calculation of low-density lipoprotein cholesterol in patients with normolipidemia and/or hypertriglyceridemia. JAMA Cardiol Published online Feb 2020.
  • Song, Y., Lee, H.S., Baik, S.J. et al. Comparison of the effectiveness of Martin’s equation, Friedewald’s equation, and a Novel equation in low-density lipoprotein cholesterol estimation. Sci Rep11, 13545 (2021)

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