LDL cholesterol calculator: Sampson, Martin-Hopkins and Friedewald
Short answer: LDL is usually calculated from total cholesterol, HDL and triglycerides rather than measured. The old Friedewald formula (total − HDL − triglycerides ÷ 5) runs low when triglycerides are high or LDL is low, and is not used above 400 mg/dL. The Martin-Hopkins and Sampson (NIH) formulas fix most of that. Below 100 mg/dL (2.6 mmol/L) is optimal.
Free calculator
LDL cholesterol calculator (Sampson, Martin-Hopkins, Friedewald)
LDL = total − HDL − a share of triglycerides (three formulas)
Sources: 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 2020;5(5):540-548.
The "good" cholesterol
Up to 800 mg/dL (9.0 mmol/L)
Your result
Enter the numbers from your lab report to see your result.
Most labs calculate LDL rather than measure it. If your report says "calculated" or "Friedewald", this is the same idea with newer formulas. A fasting sample is best when triglycerides are high.
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A pointer, not a diagnosis. Talk to a doctor about your result, and sooner if you feel unwell.
How to read the result
- Optimal (below 100 mg/dL, 2.6 mmol/L)< 100mg/dLYour LDL is in the optimal range.
- Near optimal (100–129 mg/dL, 2.6–3.3 mmol/L)100 – 130mg/dLSlightly above optimal. Whether it needs anything depends on your other heart risks, such as blood pressure, smoking, diabetes and family history.
- Borderline high (130–159 mg/dL, 3.4–4.1 mmol/L)130 – 160mg/dLBorderline high. Less saturated fat, more fibre (oats, beans, vegetables), regular exercise and losing some weight can lower LDL. A doctor can tell you whether your overall heart risk calls for more.
- High (160–189 mg/dL, 4.1–4.9 mmol/L)160 – 190mg/dLHigh. This is worth talking to a doctor about, together with your blood pressure, blood sugar and family history.
- Very high (190 or above, 4.9 mmol/L)≥ 190mg/dLVery high. An LDL this high is often partly inherited (familial hypercholesterolaemia), which is common and treatable. Please see a doctor; close relatives may want a cholesterol test too.
Your lab’s range
Labs print LDL against the same categories: below 100 mg/dL (2.6 mmol/L) optimal or desirable, 130–159 borderline high, 160 or above high. Non-HDL cholesterol is usually read 30 mg/dL (0.8 mmol/L) above the LDL ones, so below 130 mg/dL (3.4 mmol/L) is desirable. If you have heart disease or diabetes, your doctor’s target may be lower.
How it is worked out
LDL = total − HDL − a share of triglycerides (three formulas)
Most labs calculate LDL rather than measure it. If your report says "calculated" or "Friedewald", this is the same idea with newer formulas. A fasting sample is best when triglycerides are high.
Sources
- 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 2020;5(5):540-548.
- 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(19):2061-2068.
- 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.
- National Cholesterol Education Program (NCEP) Expert Panel. Third Report on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). Circulation 2002;106(25):3143-3421.
- Nordestgaard BG, Langsted A, Mora S, et al. Fasting is not routinely required for determination of a lipid profile: clinical and laboratory implications including flagging at desirable concentration cut-points. Eur Heart J 2016;37(25):1944-1958.
The markers it uses
Questions
- Which LDL formula is most accurate?
- Compared with measured LDL, the Martin-Hopkins and Sampson (NIH) formulas are more accurate than Friedewald, especially when triglycerides are above 150 mg/dL or LDL is below 70 mg/dL. Sampson also works with triglycerides up to 800 mg/dL. With normal triglycerides the three usually agree within a few mg/dL.
- How do you calculate LDL cholesterol?
- Friedewald: total cholesterol − HDL − triglycerides ÷ 5 (all in mg/dL; ÷ 2.2 in mmol/L). Martin-Hopkins swaps the fixed 5 for a factor that depends on your triglycerides and non-HDL. Sampson uses a longer equation with the same three numbers. This calculator shows all three.
- What is non-HDL cholesterol?
- Total cholesterol minus HDL: all the cholesterol in the particles that can block arteries, not only LDL. It needs no formula and no fasting, and it is a good risk marker when triglycerides are high. Below 130 mg/dL (3.4 mmol/L) is desirable for most people.
- What is remnant cholesterol?
- The cholesterol in triglyceride-rich particles: total cholesterol minus HDL minus LDL. Large studies link a higher remnant cholesterol with heart disease, independent of LDL. It is mostly a research number; it tends to fall when triglycerides do.
- Why is my calculated LDL different from my lab’s?
- Your lab may use a different formula, measure LDL directly, or round differently. A difference of a few mg/dL is normal. When triglycerides are high, the Friedewald number on many reports can be noticeably lower than the other two.
More calculators for the same system
A pointer, not a diagnosis. Talk to a doctor about your result, and sooner if you feel unwell. Reference ranges are general-population guidance compiled from common clinical laboratories, not a diagnosis. Lab-to-lab ranges differ. Always read your results with your doctor.