Calculated LDL Cholesterol (Friedewald, Martin-Hopkins and Sampson)

Three LDL equations side by side, non-HDL cholesterol, and when a calculated LDL should not be trusted · v1

  • Enter the age, then the total cholesterol, HDL cholesterol and triglycerides from one report, and whether the sample was fasting.
  • Choose the unit once. mg/dL is the default; switch to mmol/L if the report prints it, and every lipid field follows.
  • Tick the direct LDL box if the report also prints a measured LDL, to see how far each equation differs from it.
  • You get the LDL by Martin-Hopkins, Sampson and Friedewald side by side, the non-HDL and remnant cholesterol, and flags for the settings in which a calculated LDL misleads.
  • The verdict leads with Martin-Hopkins below 400 mg/dL of triglycerides and with Sampson from 400 to 800, and says how far to trust the number. It is not a treatment goal.

  • Children and adolescents under 18. Paediatric lipid cut-offs differ, and a raised LDL in a child is a question about familial hypercholesterolaemia. The tool refuses the age.
  • The LDL goal, and the choice of drug. The goal depends on cardiovascular risk, which CVD Risk and CKM Staging works out; residual-risk markers are in the Atherogenic and Residual Risk Pathway.
  • The diagnosis of familial hypercholesterolaemia, which needs the family history, the examination and formal criteria. The tool flags an LDL of 190 mg/dL or more and stops there.
  • A calculated LDL at triglycerides above 800 mg/dL, and the extended Martin-Hopkins table for 400 to 799 mg/dL, which we could not verify from two sources.
  • Pregnancy and type III dysbetalipoproteinaemia. We found no validation of these equations in pregnancy, and type III cannot be recognised from a standard lipid profile.

1. The Patient

Adults only. Below 18 the tool declares itself out of scope and stops.

2. The Lipid Report

One unit for the whole report. Cholesterol: 1 mmol/L is 38.67 mg/dL. Triglycerides: 1 mmol/L is 88.57 mg/dL.
A non-fasting sample is accepted for screening. It changes the flags, not the arithmetic.

3. Clinical Context (Optional)

None of these changes the arithmetic. Each one adds the flag that bears on reading the LDL.

1. Three Equations From One Lipid Profile

All three subtract an estimate of VLDL cholesterol from the non-HDL cholesterol. They differ only in how that estimate is made.

EquationLDL cholesterol, mg/dLDerived fromUsed here
Friedewald, 1972TC − HDL − TG/5448 patients with familial hyperlipoproteinaemia or their relativesBelow 400 mg/dL triglycerides, for comparison
Martin-Hopkins, 2013TC − HDL − TG/factor, the factor (3.1 to 9.5) read from a 180-cell table of triglyceride and non-HDL strata1,350,908 lipid profiles, cholesterol measured after ultracentrifugationBelow 400 mg/dL, leading
Sampson (NIH), 2020TC/0.948 − HDL/0.971 − (TG/8.56 + TG × non-HDL/2140 − TG²/16100) − 9.448656 patients, 18,715 beta-quantification resultsUp to 800 mg/dL; leading from 400

2. Why Friedewald Reads Low

The factor of 5 fixes the ratio of triglyceride to VLDL cholesterol. In the Martin-Hopkins data the median ratio was 5.2, and it climbed as triglycerides rose, so at high triglycerides TG/5 overstates the VLDL and the LDL comes out low. The same error in the VLDL is a larger share of a small LDL, which is why it matters most when the LDL itself is low.

TriglyceridesEstimate below 70 confirmed below 70: Martin-HopkinsFriedewald
100 to 149 mg/dL94.3%79.9%
150 to 199 mg/dL92.4%61.3%
200 to 399 mg/dL84.0%40.3%

3. Which Equation This Tool Leads With

The choice follows the triglyceride level, because each equation was validated over a different range. The verdict names the equation it used every time.

  • Martin-Hopkins below 400 mg/dL. The National Lipid Association recommends it across the LDL range up to 399 mg/dL, and the 2026 ACC/AHA guideline prefers Martin-Hopkins or Sampson over Friedewald and over direct assays.
  • Sampson from 400 to 800 mg/dL. It is the only one of the three reported accurate to 800. The National Lipid Association recommends no estimating equation at 400 or more, so the tool marks the result as a wider estimate.
  • None above 800 mg/dL. The non-HDL cholesterol is the number to use.
  • Not built in: the extended Martin-Hopkins table for 400 to 799 mg/dL and the 2025 modified Sampson equation, because neither could be verified from two sources.

4. Where the Sources Disagree

The documents behind this tool differ on four points. Both positions are printed here, and where the tool has had to choose, section 3 says what it chose.

QuestionOne positionThe other
An equation at triglycerides 400 to 800None recommended (NLA 2021)Sampson accurate to 800 (Sampson 2020)
Martin-Hopkins or Sampson in the PCSK9 inhibitor trialsMartin-Hopkins closer to ultracentrifugation than Friedewald (FOURIER, 2018)NIH equation the most accurate once triglycerides exceed 150 (alirocumab trials, 2022)
Repeat a non-fasting sample fasting when triglycerides exceed175 mg/dL (NLA 2021); 400 mg/dL (ACC/AHA 2026)440 mg/dL (EAS/EFLM 2016)
Triglycerides that carry a risk of pancreatitisAbove 880 mg/dL (EAS/EFLM 2016)1000 mg/dL (ACC/AHA 2026)

5. Validation in Indian Patients

In 3028 Indian patients undergoing coronary revascularisation, all three equations read below the direct LDL. Martin-Hopkins fell short by the least: a mean of 5.2 mg/dL, against 7.2 for Sampson and 10.5 for Friedewald. Friedewald placed 24.6 per cent of those with a direct LDL above 70 mg/dL below 70. The reference in such studies is a direct assay, not ultracentrifugation, so part of each difference belongs to the assay.

6. Non-HDL and Remnant Cholesterol

Two more values come from the same report at no extra cost. One is sturdier than any calculated LDL; the other is easily over-read.

  • Non-HDL cholesterol is total minus HDL. It needs no VLDL estimate and is reliable fasting or not. The Lipid Association of India treats it as a co-primary target beside LDL, with apolipoprotein B as a secondary target.
  • Remnant cholesterol is total minus HDL minus LDL. From a calculated LDL it is only the equation's own VLDL estimate; from a direct LDL it is a separate figure. EAS/EFLM flags a calculated value of 35 mg/dL or more on a non-fasting sample; the National Lipid Association does not recommend it for initial evaluation.

7. When No Calculated LDL Should Be Trusted

Some profiles defeat every equation, and the verdict then says so rather than printing a number.

  • Triglycerides above 800 mg/dL, where none of the three is valid.
  • Type III dysbetalipoproteinaemia, where Martin-Hopkins and Friedewald are furthest from the measured value. It needs an apolipoprotein B to recognise.
  • A direct assay is not the answer at high triglycerides either, because its accuracy also falls as they rise.
Abbreviations ACC (American College of Cardiology) · AHA (American Heart Association) · apoB (Apolipoprotein B) · CKM (Cardiovascular-Kidney-Metabolic) · CVD (Cardiovascular Disease) · EAS (European Atherosclerosis Society) · EFLM (European Federation of Clinical Chemistry and Laboratory Medicine) · FOURIER (Further Cardiovascular Outcomes Research With PCSK9 Inhibition in Subjects With Elevated Risk) · HDL (High-Density Lipoprotein) · LDL (Low-Density Lipoprotein) · NIH (National Institutes of Health) · NLA (National Lipid Association) · PCSK9 (Proprotein Convertase Subtilisin/Kexin Type 9) · TC (Total Cholesterol) · TG (Triglycerides) · VLDL (Very Low-Density Lipoprotein)
References
  1. 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(6):499-502.
  2. Martin SS, Blaha MJ, Elshazly MB, Toth PP, Kwiterovich PO, Blumenthal RS, 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(19):2061-8.
  3. Sampson M, Ling C, Sun Q, Harb R, Ashmaig M, Warnick R, et al. A new equation for calculation of low-density lipoprotein cholesterol in patients with normolipidemia and/or hypertriglyceridemia. JAMA Cardiol. 2020;5(5):540-8.
  4. Martin SS, Giugliano RP, Murphy SA, Wasserman SM, Stein EA, Ceška R, et al. Comparison of low-density lipoprotein cholesterol assessment by Martin/Hopkins estimation, Friedewald estimation, and preparative ultracentrifugation: insights from the FOURIER trial. JAMA Cardiol. 2018;3(8):749-53.
  5. Ginsberg HN, Rosenson RS, Hovingh GK, Letierce A, Samuel R, Poulouin Y, et al. LDL-C calculated by Friedewald, Martin-Hopkins, or NIH equation 2 versus beta-quantification: pooled alirocumab trials. J Lipid Res. 2022;63(1):100148.
  6. Wilson PWF, Jacobson TA, Martin SS, Jackson EJ, Le NA, Davidson MH, et al. Lipid measurements in the management of cardiovascular diseases: practical recommendations a scientific statement from the national lipid association writing group. J Clin Lipidol. 2021;15(5):629-48.
  7. Nordestgaard BG, Langsted A, Mora S, Kolovou G, Baum H, Bruckert E, et al. Fasting is not routinely required for determination of a lipid profile: clinical and laboratory implications including flagging at desirable concentration cut-points. A joint consensus statement from the European Atherosclerosis Society and European Federation of Clinical Chemistry and Laboratory Medicine. Eur Heart J. 2016;37(25):1944-58.
  8. Blumenthal RS, Morris PB, Gaudino M, Johnson HM, Anderson TS, Bittner VA, et al. 2026 ACC/AHA/AACVPR/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA guideline on the management of dyslipidemia: a report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2026;153(17):e1154-e1276.
  9. Puri R, Mehta V, Bansal M, Shetty S, Yusuf J, Agarwala R, et al. Navigating cardiovascular risk and lipid management in Indian patients: key messages from the Lipid Association of India 2024 Consensus Statement IV. J Assoc Physicians India. 2024;72(8):80-2.
  10. Bansal M, Kaushal P, Kasliwal RR, Chandra P, Kapoor R, Chouhan N, et al. Different methods of low-density lipoprotein cholesterol estimation and the impact on lipid-lowering therapy in patients with coronary artery disease. J Assoc Physicians India. 2026;74(2):57-61.
How to Cite This Tool

AMA Style:Umakanth S. Calculated LDL Cholesterol (Friedewald, Martin-Hopkins and Sampson). Version 1. MEDiscuss Clinical Decision Support System. Published 2026. Accessed . https://mediscuss.org/cdss/ldl-calculator

Vancouver Style:Umakanth S. Calculated LDL Cholesterol (Friedewald, Martin-Hopkins and Sampson) [Internet]. Version 1. MEDiscuss.org; 2026 [cited ]. Available from: https://mediscuss.org/cdss/ldl-calculator

Disclaimer and scope
Disclaimer: This decision-support system is written for healthcare professionals. It does not substitute clinical judgment, and the treating physician retains absolute responsibility for every diagnostic, dosing and therapeutic decision. The algorithms are built on the evidence as it stands, and the evidence moves. Verify the output against your current institutional protocol, and against the patient in front of you.
© 2026 MEDiscuss.org. All rights reserved. Provided free of charge for clinical use. Unauthorised reproduction or redistribution is strictly prohibited.
Category Foundational CalculatorsCalculator
Specialties Cardiology, Internal Medicine, Endocrinology, Biochemistry, Family Medicine

Written and maintained by

Dr Shashikiran Umakanth

Last revised 23 September 2026

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