Audited 29 Jul 2026·Last updated 28 Oct 2026·5 citations·Tier 1·0 uses

LDL Cholesterol Calculator

Work out Friedewald LDL cholesterol, estimated VLDL and non-HDL cholesterol from total cholesterol, HDL and triglycerides, entered in mg/dL or mmol/L.

LDL Cholesterol Calculator

Unit system
Calculated LDL cholesterol
132
Calculated LDL cholesterol in mg/dL (total − HDL − triglycerides ÷ 5); an estimate that supports, not replaces, your clinician's interpretation, and not given when triglycerides are above the cutoff.
Estimated VLDL cholesterol
32
Non-HDL cholesterol
164

Background.

Look closely at a standard lipid panel and you may see a small 'calc' beside the LDL line. In many laboratories LDL cholesterol is not measured at all. The analyser measures total cholesterol, HDL cholesterol and triglycerides, and LDL is worked out from those three with a subtraction published by William Friedewald, Robert Levy and Donald Fredrickson in 1972. That equation is what this calculator runs, so you can check the figure on your report, see where it came from, or calculate it yourself from an older panel that never printed it.

The idea is bookkeeping. Total cholesterol is the cholesterol carried by every lipoprotein particle in the blood. Take away what HDL carries, and what is left sits mostly in LDL and in VLDL, the triglyceride-rich particles made by the liver. VLDL cholesterol is rarely measured directly, so Friedewald estimated it as one fifth of the triglyceride level in mg/dL, on the observation that VLDL particles carry about five times as much triglyceride as cholesterol. Subtract that too, and the remainder is LDL.

The weak link is that one-fifth assumption. After a fatty meal, chylomicrons from the gut flood the blood with triglyceride that carries little cholesterol, and in some lipid disorders the ratio inside VLDL changes. In either case triglycerides ÷ 5 overstates VLDL cholesterol and the calculated LDL comes out too low. The traditional limit is a triglyceride level of 400 mg/dL, above which the estimate should not be used, and many laboratories now report a direct LDL measurement or use a newer equation instead.

Non-HDL cholesterol, total minus HDL, is reported alongside because it needs no assumption about triglycerides at all. None of these numbers is a diagnosis. Whether a given LDL calls for diet changes, more tests or medication depends on your overall cardiovascular risk, which is a judgement for your clinician; the calculator supports that conversation rather than replacing it.

What is ldl cholesterol calculator?

LDL cholesterol is the cholesterol carried in low-density lipoprotein particles, the main carriers of cholesterol to the tissues and the particles most strongly linked to the build-up of plaque in artery walls. Lowering LDL cholesterol with diet or medication reduces heart attacks and strokes in large clinical trials, which is why it is the number most treatment plans are built around. A Friedewald LDL is an estimate, not a measurement: it is whatever cholesterol remains after HDL cholesterol and an estimate of VLDL cholesterol are subtracted from the total. That remainder also includes the small amounts carried by intermediate-density lipoprotein and lipoprotein(a), which the subtraction cannot separate from LDL. Laboratories can instead measure LDL directly with dedicated assays, or calculate it with newer equations such as the Martin-Hopkins method, which replaces the fixed factor of 5 with one chosen from the triglyceride and non-HDL levels, and the NIH (Sampson) equation designed for higher triglycerides. Those methods are not computed here.

How to use this calculator.

  1. Take total cholesterol, HDL cholesterol and triglycerides from the same blood sample; mixing results from different days breaks the subtraction. Cholesterol results also vary by several percent from one test to the next, so a single borderline value is often repeated before anything is decided.
  2. Choose mg/dL if your report is in mg/dL, as most in the United States are, or mmol/L if it uses the international unit. All three values must be in the unit you choose.
  3. Read the results in mg/dL: the calculator reports in mg/dL whichever unit you entered. To get mmol/L, divide any of the three results by 38.67.
  4. Check your triglycerides against the cutoff field, 400 mg/dL by default (about 4.52 mmol/L). If yours are above the cutoff the calculator refuses to give an LDL, because the equation is not valid there; rely on non-HDL cholesterol or ask for a direct LDL instead.
  5. Compare the result with the LDL printed on your report. If the two differ, the report probably names a direct measurement or a different equation, and the laboratory's figure is the one your clinician will use.

The formula.

LDL = TC − HDL − TG ⁄ 5
LDL · calculated LDL cholesterol (mg/dL)TC · total cholesterol (mg/dL)HDL · HDL cholesterol (mg/dL)TG ⁄ 5 · estimated VLDL cholesterol: triglycerides ÷ 5 (mg/dL)

In mg/dL the calculation is three lines. Estimated VLDL cholesterol = TG ÷ 5. LDL = TC − HDL − TG ÷ 5. Non-HDL = TC − HDL. TC is total cholesterol, HDL is HDL cholesterol and TG is triglycerides. The factor 5 is the assumed ratio of triglyceride to cholesterol inside VLDL particles, by mass. It holds reasonably well in fasting samples with moderate triglycerides and fails as triglycerides climb, because the extra triglyceride arrives in particles carrying proportionally less cholesterol. When you enter mmol/L, cholesterol values are multiplied by 38.66976 and triglycerides by 88.57396 to convert them to mg/dL before the same arithmetic runs. The two factors differ because a mole of triglyceride weighs much more than a mole of cholesterol. In mmol/L terms that is the same as dividing triglycerides by about 2.183, close to the 2.2 many laboratories use for the SI version of the equation. Every 1 mg/dL of triglycerides lowers the calculated LDL by 0.2 mg/dL, which is why a raised triglyceride result after a meal can pull the LDL down without any real change. The 1972 paper checked the estimate against LDL measured with the preparative ultracentrifuge and excluded samples with chylomicrons present and patients with type III hyperlipoproteinaemia (dysbetalipoproteinaemia), whose VLDL is unusually rich in cholesterol; the equation should not be used in either situation. Because LDL is a difference between measured values, small measurement errors grow in relative terms: if total cholesterol in the example read 3% high, 218.36 instead of 212, the calculated LDL would rise by 6.36 mg/dL, almost 5% of 132. HDL must not exceed total cholesterol, since HDL is part of the total.

A worked example.

Example

A panel shows total cholesterol 212 mg/dL, HDL 48 mg/dL and triglycerides 160 mg/dL. Estimated VLDL cholesterol is 160 ÷ 5 = 32 mg/dL. Non-HDL cholesterol is 212 − 48 = 164 mg/dL, everything not carried by HDL. Taking the VLDL estimate off that leaves 164 − 32 = 132 mg/dL of calculated LDL cholesterol. Triglycerides of 160 are well under the 400 mg/dL cutoff, so the equation's assumption is on reasonably safe ground. In mmol/L the same LDL is 132 ÷ 38.67, about 3.41 mmol/L. Suppose the same person had eaten before a repeat test and triglycerides came back at 260 mg/dL with total and HDL unchanged. VLDL becomes 52, and LDL drops to 112 mg/dL, although nothing about their LDL particles has changed. Non-HDL stays at 164, which is why it is the steadier figure when triglycerides vary. A report in mmol/L reading total 5.5, HDL 1.2 and triglycerides 1.8 goes through the same steps after conversion: 5.5 × 38.66976 = 212.68 mg/dL, 1.2 × 38.66976 = 46.40 mg/dL and 1.8 × 88.57396 = 159.43 mg/dL. VLDL is 159.43 ÷ 5 = 31.89, and LDL is 212.68 − 46.40 − 31.89 = 134.39, displayed as 134 mg/dL. Dividing by 38.67 returns about 3.48 mmol/L, the same to two decimals as the familiar SI shortcut 5.5 − 1.2 − 1.8 ÷ 2.2.

hdl Cholesterol48
triglyceride Cutoff400
fasting Statusfasting
total Cholesterol212
triglycerides160
unit Systemmgdl

Frequently asked questions.

Why is my calculated LDL different from the LDL on my lab report?
Your laboratory may have measured LDL directly or used a newer equation such as Martin-Hopkins or Sampson, which give different results from Friedewald, particularly when triglycerides are high or LDL is low. Rounding of the inputs on the printed report also shifts the answer by a point or two. If the report names its method, that tells you which figure to trust.
Do I need to fast before a cholesterol test?
Many guidelines now accept a non-fasting sample for routine checks, because total and HDL cholesterol change little after a meal. Triglycerides do rise, and because they feed the Friedewald subtraction a non-fasting sample tends to give a lower calculated LDL. If your triglycerides are high or the LDL is borderline for a treatment decision, your clinician may ask for a repeat after fasting, which usually means nothing but water for 9 to 12 hours beforehand.
What happens to the calculation when triglycerides are very high?
It breaks down. With total cholesterol 200, HDL 40 and triglycerides 900 mg/dL, the estimated VLDL is 180 and the calculated LDL is −20 mg/dL, an impossible value, while non-HDL cholesterol for the same sample is a perfectly usable 160 mg/dL. Long before that point the estimate is too low. The calculator therefore refuses to report an LDL when triglycerides are above the cutoff, and it never shows a negative value; it asks you to use non-HDL cholesterol or a direct LDL instead.
Is the estimate less accurate when LDL is already low?
Yes. The error from the fixed factor of 5 matters most when triglycerides are raised and LDL is low, because a few mg/dL of misjudged VLDL is then a large share of what remains. That is the situation of many people on cholesterol-lowering treatment, and it is the main reason the Martin-Hopkins and Sampson equations were developed and are increasingly used by laboratories.
What is the triglyceride cutoff field for?
It sets the level above which the calculator will not estimate LDL: 400 mg/dL by default, the limit the 1972 authors applied to this equation, adjustable from 100 to 1,000 mg/dL if your laboratory works to a stricter one. It is always in mg/dL, even when you enter results in mmol/L. Triglycerides above it produce an error message instead of an LDL; non-HDL cholesterol is not affected.
Why do cholesterol and triglycerides use different mmol/L conversions?
A millimole is a count of molecules, and a triglyceride molecule weighs more than twice as much as a cholesterol molecule. So 1 mmol/L of cholesterol is about 38.67 mg/dL, while 1 mmol/L of triglycerides is about 88.57 mg/dL. Applying the cholesterol factor to triglycerides would understate them badly and inflate the calculated LDL. To go back from mg/dL to mmol/L, divide by the same factors: 160 mg/dL of triglycerides is about 1.81 mmol/L.
Is non-HDL cholesterol more useful than LDL?
It answers a slightly broader question. Non-HDL counts the cholesterol in every particle that can contribute to plaque: LDL, VLDL and its remnants, intermediate-density lipoprotein and lipoprotein(a). It needs no triglyceride assumption, so it stays dependable in non-fasting samples and with high triglycerides. Many guidelines use it as a secondary target. In the example it is 164 mg/dL against an LDL of 132.
Can I enter results from a home cholesterol test kit?
You can if the kit reports total cholesterol, HDL and triglycerides from a single sample. Home and finger-prick devices are generally less precise than laboratory analysers, and any error in the three inputs passes straight into the subtraction, so a calculated LDL from a kit is a rough guide. A laboratory panel is the basis for clinical decisions.
Does a higher HDL lower my calculated LDL?
Arithmetically yes, if total cholesterol stays the same: every extra mg/dL of HDL is one less left over for LDL. In real life, HDL and total cholesterol usually move together, because HDL is part of the total. Since HDL cannot exceed total cholesterol, the calculator rejects an HDL larger than the total, which usually means a typing or unit error. HDL particles carry cholesterol away from the tissues back to the liver, which is why HDL is counted separately from the cholesterol that can build up in arteries.
Will this tell me whether I need a statin?
No. Treatment decisions combine LDL with age, blood pressure, smoking, diabetes, kidney disease, family history and any existing heart or vascular disease, usually through a formal risk estimate such as the pooled cohort equations, which turn those factors into a 10-year risk of heart attack or stroke. A very high LDL can also point to an inherited condition, familial hypercholesterolaemia, that needs its own assessment. Use the result to understand your report, and discuss what it means with your clinician.

References& sources.

  1. [1]Friedewald, W.T., Levy, R.I., and Fredrickson, D.S. (1972). Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge. Clinical Chemistry. PubMed.
  2. [2]Centers for Disease Control and Prevention (2025). About Cholesterol. CDC.
  3. [3]National Heart, Lung, and Blood Institute (2002). Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults. NHLBI.
  4. [4]U.S. Food and Drug Administration (2024). Cholesterol Tests. FDA.
  5. [5]American Heart Association (2024). Your Complete Guide to Understanding Cholesterol and Lipids. AHA.

How this page was produced

Published by
Quanta Calculator
Overseen by
Daniel, Quanta Calculator Researcher
Primary sources
5 cited below
Method
LDL = TC − HDL − TG ⁄ 5
Published
Last verified

Built with AI assistance and verified by automated tests against the cited sources — every worked example on this page is computed by the same code that runs the calculator. How we build and check calculators.

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