Traditional Friedewald LDL-C Calculator

It estimates LDL cholesterol concentration from total cholesterol, HDL cholesterol and triglycerides in one lipid panel. It reproduces the 1972 Friedewald arithmetic only; it is not a direct LDL-C measurement, LDL particle count, apolipoprotein B result or cardiovascular-risk score.

Sources: [1, 6]

LDL-C = total cholesterol − HDL-C − (triglycerides ÷ 5), with all three submitted measurements in mg/dL. The triglyceride-divisor term is a traditional estimate of VLDL-C, not a measured VLDL-C value.

Sources: [1]

LDL-C = total cholesterol − HDL-C − (triglycerides ÷ 2.2), with all three submitted measurements in mmol/L. The page does not convert a mixed-unit panel or use the mg/dL divisor in SI units.

Sources: [1]

The original method used a fixed triglyceride-to-VLDL-cholesterol relationship: 5 when concentrations are expressed in mg/dL and 2.2 in mmol/L. That relationship varies between samples and people, which is an important limitation of the estimate.

Sources: [1]

No. It is subtraction-based estimation. A homogeneous direct assay and preparative ultracentrifugation use different measurement procedures, and results from those methods or from other equations are not assumed to be interchangeable with this Friedewald result.

Sources: [1, 6]

This page uses a strict half-open boundary: 399.9 mg/dL and 4.49 mmol/L can be submitted, while 400 mg/dL and 4.5 mmol/L are withheld. At and above the boundary, use the LDL-C method selected and reported by the laboratory or clinical workflow.

Sources: [1, 6]

No. It only permits the historical arithmetic. The fixed TG:VLDL-C assumption can still disagree with a reference method, particularly when triglycerides are higher or LDL-C is lower. Sampling and assay variation also remain.

Sources: [1, 2, 5]

Not in the current U.S. guideline. The 2026 ACC/AHA multisociety dyslipidemia guideline prefers Martin/Hopkins or Sampson/NIH over Friedewald for estimation from a standard lipid profile. This page intentionally stays with the 1972 model and never switches methods silently.

Sources: [3, 4, 10, 11]

No. Total cholesterol, HDL-C and triglycerides must come from the same specimen and use the one selected unit. Changing the unit clears every value so an old number cannot be reinterpreted silently.

Sources: [1]

The original 1972 Friedewald relationship was derived from fasting plasma data and depends on a fixed triglyceride-to-VLDL-C ratio. Modern guidance allows fasting or nonfasting standard lipid profiles for many people and prefers Martin/Hopkins or Sampson/NIH for estimated LDL-C. The fixed historical assumption may not hold with triglyceride metabolism abnormalities, chylomicrons, type III dysbetalipoproteinemia, or clearly high triglycerides. This page cannot identify whether a sample was truly fasting, contains chylomicrons, has type III dysbetalipoproteinemia or unusual VLDL composition, or which LDL-C method the laboratory used. Being below 400 mg/dL or 4.5 mmol/L only permits this historical arithmetic; it does not prove that the estimate is accurate or applicable to the sample.

Sources: [1, 6, 9]

Non-HDL-C is total cholesterol minus HDL-C. It includes cholesterol in multiple atherogenic lipoprotein classes and is shown as transparent intermediate arithmetic; it is not the same value as Friedewald LDL-C.

Sources: [6, 8]

No. LDL-C estimates cholesterol mass carried within LDL particles. It does not count particles. Apolipoprotein B and other particle-related tests answer different questions and are not derived by this calculator.

Sources: [6, 8]

The laboratory may use Martin/Hopkins, Sampson/NIH, a homogeneous direct assay or another stated method, and rounding or assay calibration can also differ. Confirm the method on the report before comparing values and avoid treating unlike methods as interchangeable trends.

Sources: [2, 3, 4, 5, 6]

For some combinations, the fixed triglyceride-divisor term is as large as or larger than non-HDL-C. The page does not clamp that arithmetic to zero or present it as a usable LDL-C estimate; it withholds the result and asks for verification.

Sources: [1, 6]

No. The arithmetic has only total cholesterol, HDL-C, triglycerides and unit. Age, pregnancy, diabetes, kidney or liver disease, genetic dyslipidemia, medicines and assay quality may affect clinical interpretation or method choice but are not modeled here.

Sources: [6, 10]

No. The page supplies neutral historical arithmetic only. It does not diagnose a lipid disorder, calculate ASCVD risk, establish a patient-specific goal, select a medicine, prescribe a dose or recommend treatment.

Sources: [10, 11]