LDL Cholesterol Calculator
This calculates LDL ("bad") cholesterol from a standard lipid panel. It uses the 2020 NIH equation, which stays accurate at higher triglycerides and does not require fasting, and shows the older Friedewald result for comparison.
| Result | Interpretation |
|---|---|
| Below 100 mg/dL | Optimal |
| 100 mg/dL to 130 mg/dL | Near optimal/above optimal |
| 130 mg/dL to 160 mg/dL | Borderline high |
| 160 mg/dL to 190 mg/dL | High |
| 190 mg/dL and above | Very high |
Source: 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. (doi:10.1001/jamacardio.2020.0013); 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.; Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults. Executive Summary of the Third Report of the NCEP (ATP III). JAMA 2001;285(19):2486-2497. (doi:10.1001/jama.285.19.2486)
This calculator runs entirely in your browser. Enable JavaScript to use the interactive version. Nothing you enter is sent to a server.
For your 10-year heart attack and stroke risk, use the ASCVD risk calculator.
How LDL is calculated
LDL is usually calculated rather than measured directly, from total cholesterol, HDL and triglycerides.
NIH (Sampson) equation, 2020:
LDL = TC/0.948 − HDL/0.971 − (TG/8.56 + TG × non-HDL/2140 − TG²/16100) − 9.44
where non-HDL = TC − HDL, and all values are in mg/dL. In the NIH study it was as accurate up to triglycerides of 800 mg/dL as the older Friedewald equation is below 400, and it does not depend on fasting.
Friedewald equation, 1972:
LDL = TC − HDL − TG/5 (mg/dL), or TC − HDL − TG/2.2 in mmol/L
It needs a fasting sample and cannot be used when triglycerides are above 400 mg/dL (4.5 mmol/L).
A third method, Martin/Hopkins, is used by some labs but requires a license from Johns Hopkins, so it is not offered here.
Worked example
Total cholesterol 200, HDL 50, triglycerides 150 mg/dL:
- Sampson: 123 mg/dL
- Friedewald: 200 − 50 − 30 = 120 mg/dL
How the two equations compare as triglycerides rise
Total cholesterol 200 and HDL 50 mg/dL, with different triglyceride levels:
| Triglycerides (mg/dL) | Sampson LDL (mg/dL) | Friedewald LDL (mg/dL) |
|---|---|---|
| 75 | 136 | 135 |
| 150 | 123 | 120 |
| 250 | 107 | 100 |
| 350 | 92 | 80 |
| 450 | 79 | Not valid |
| 600 | 60 | Not valid |
| 800 | 40 | Not valid |
At normal triglycerides the two agree within a few points. They split apart as triglycerides climb, and above 400 only the Sampson result is usable. Above 800, neither equation is reliable and LDL should be measured directly.
LDL categories
| LDL (mg/dL) | Category (NCEP ATP III) |
|---|---|
| Below 100 | Optimal |
| 100 to 129 | Near optimal/above optimal |
| 130 to 159 | Borderline high |
| 160 to 189 | High |
| 190 or above | Very high |
These categories describe the number itself. Whether you need treatment depends on your overall risk, which is why your physician may set a lower target if you have heart disease or diabetes.
FAQs
Which LDL equation is most accurate?
In the NIH study, the Sampson equation was as accurate for triglycerides up to 800 mg/dL as Friedewald is below 400, and caused 35% fewer misclassifications in people with triglycerides of 400 to 800. At normal triglycerides the two give similar answers.
Do I need to fast for an LDL test?
Not for the Sampson equation, which the NIH team found was unaffected by fasting. The Friedewald equation was designed for fasting samples.
What is non-HDL cholesterol?
Total cholesterol minus HDL. It counts the cholesterol carried in all particles other than HDL, so it needs no LDL equation.
My triglycerides are over 800. Why no result?
No LDL equation has been shown to be reliable at that level. Ask your lab for a directly measured LDL.