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LDL Calculator

Health

Calculate LDL cholesterol from total cholesterol, HDL, and triglycerides using the Friedewald formula, with a risk category noted instantly.

Reviewed by the thecalcu.com team · Last updated July 23, 2026

Total Cholesterol
mg/dL
100400
HDL Cholesterol
mg/dL
20100
Triglycerides
mg/dL
501000

LDL Cholesterol

0mg/dL

Risk Category

—

For informational purposes only. This estimate is not a substitute for a laboratory lipid panel — discuss your results with a healthcare provider.

What is a LDL Calculator?

An LDL Calculator estimates low-density lipoprotein (LDL) cholesterol, often called "bad cholesterol", from three values found on a standard lipid panel: total cholesterol, HDL cholesterol, and triglycerides. It applies the Friedewald formula, the same equation most clinical labs use to report a calculated LDL value rather than measuring LDL directly.

Because LDL is rarely measured directly in routine testing, understanding how it's derived from the other numbers on your lipid panel, and where that calculation breaks down, helps you interpret your results more confidently.

Why Use an LDL Calculator?

If you have a recent lipid panel in hand, this calculator lets you verify or recalculate your LDL figure and immediately see which NCEP ATP III risk category it falls into. It's also useful for understanding how changes in HDL or triglycerides, tracked over time, shift your calculated LDL, even before your total cholesterol changes.

Because the Friedewald formula has a well-known limitation at high triglyceride levels, this calculator also flags when your inputs fall outside the formula's valid range, so you know when a direct LDL test is the better source of truth.

Who Should Use This Calculator?

  • Anyone with a recent lipid panel who wants to double-check or better understand their calculated LDL result.
  • People monitoring cholesterol trends between annual checkups, alongside tools like the Cholesterol Ratio Calculator.
  • People with elevated triglycerides who want to understand why their lab report might flag LDL as "unable to calculate."
  • Healthcare and nutrition students studying how lipid panel values relate to one another.

This calculator is for informational and educational purposes only and does not replace a laboratory lipid panel or clinical risk assessment. Always interpret cholesterol results together with a qualified healthcare provider.

What Insights Does the LDL Calculator Give You?

  • LDL Cholesterol, the primary result, your estimated LDL level in mg/dL based on the Friedewald formula.
  • Risk Category, where that LDL value falls among NCEP ATP III categories: optimal, near/above optimal, borderline high, high, or very high, or a caveat if triglycerides are too high for the formula to apply.

Because LDL is a calculated rather than directly measured value in most panels, small variations in HDL or triglycerides can noticeably shift the estimated LDL and its risk category.

How to use this LDL Calculator calculator

  1. Locate your most recent lipid panel results.
  2. Enter your Total Cholesterol value in mg/dL.
  3. Enter your HDL Cholesterol value in mg/dL.
  4. Enter your Triglycerides value in mg/dL.
  5. Review the LDL Cholesterol result and its Risk Category, noting the high-triglyceride caveat if it appears.
  6. Compare the result to the LDL value on your lab report, and discuss any differences with your healthcare provider.
Show formula & methodology ↓Show less ↑

Formula & Methodology

LDL Cholesterol (mg/dL) = Total Cholesterol − HDL Cholesterol − (Triglycerides ÷ 5)

This is the Friedewald formula (Friedewald, Levy, and Fredrickson, Clinical Chemistry, 1972), the standard method labs use to calculate LDL from a routine lipid panel. It is considered unreliable when triglycerides exceed 400 mg/dL, at which point a direct LDL measurement is recommended instead.

Worked example: for total cholesterol of 200 mg/dL, HDL of 50 mg/dL, and triglycerides of 150 mg/dL: LDL = 200 − 50 − (150 ÷ 5) = 200 − 50 − 30 = 120 mg/dL, which falls in the near/above optimal category.

For a fuller definition, see our glossary entry on LDL.

Frequently Asked Questions

What is LDL cholesterol and why does it matter?
LDL (low-density lipoprotein) cholesterol is often called 'bad cholesterol' because elevated levels are associated with a buildup of plaque in artery walls, raising the risk of heart disease and stroke over time. Most standard lipid panels report LDL as a calculated value rather than a direct measurement, which is where the Friedewald formula comes in.
What is the Friedewald formula?
The Friedewald formula estimates LDL cholesterol using three values from a standard lipid panel: LDL = Total Cholesterol − HDL Cholesterol − (Triglycerides ÷ 5). It was developed by Friedewald and colleagues in 1972 and remains the most widely used method for calculating LDL in routine clinical lab reports.
Why is the Friedewald formula invalid above 400 mg/dL triglycerides?
The formula assumes a fixed ratio between triglycerides and VLDL cholesterol that only holds reasonably well at triglyceride levels below about 400 mg/dL. Above that threshold, VLDL composition shifts enough that the estimate becomes unreliable, and a direct LDL measurement or an alternative equation is recommended instead.
What LDL level is considered healthy?
According to NCEP ATP III guidelines, an LDL below 100 mg/dL is considered optimal, 100-129 mg/dL is near or above optimal, 130-159 mg/dL is borderline high, 160-189 mg/dL is high, and 190 mg/dL or above is very high. Your target range may differ based on personal risk factors such as diabetes or prior cardiovascular events, which your healthcare provider takes into account.
Should I fast before a lipid panel used for this calculator?
Many labs now allow non-fasting lipid panels for general screening, but fasting for 9-12 hours is still often recommended when triglycerides need to be measured accurately, since eating shortly before the blood draw can temporarily raise triglyceride levels. Follow your lab or provider's specific instructions for your test.
How is this different from a direct LDL test?
A direct LDL test physically measures LDL particles in the blood sample rather than estimating them from other values, making it more accurate when triglycerides are very high or when someone has just eaten. Most routine lipid panels use the calculated Friedewald method because it is less expensive and sufficiently accurate for most people under normal conditions.
How does LDL relate to VLDL cholesterol?
VLDL (very low-density lipoprotein) cholesterol is estimated as triglycerides divided by 5 and represents a separate cholesterol-carrying particle from LDL, though the Friedewald formula uses that VLDL estimate as part of calculating LDL. You can calculate VLDL directly using the [VLDL Calculator](/vldl-calculator/) with the same triglyceride value.
What if my total cholesterol and HDL are in mmol/L instead of mg/dL?
Convert your values to mg/dL first using the [Cholesterol Units Converter](/cholesterol-units-converter/), since this calculator's inputs are designed for mg/dL. Mixing units would produce an incorrect LDL estimate.
How often should LDL cholesterol be checked?
General screening guidelines suggest a lipid panel every 4-6 years for most healthy adults, with more frequent testing recommended for people with risk factors such as diabetes, family history of heart disease, or prior abnormal results. Your healthcare provider can recommend a personalized testing schedule.
Can lifestyle changes lower LDL cholesterol?
Dietary changes such as reducing saturated fat, increasing soluble fiber, regular physical activity, and maintaining a healthy weight can meaningfully lower LDL cholesterol for many people. For some individuals, medication such as statins may also be needed, and any treatment decisions should be made with a qualified healthcare provider.
Does this calculator diagnose high cholesterol or heart disease risk?
No, this calculator only performs the Friedewald calculation and reports the corresponding NCEP ATP III risk category based on the numbers you enter. It does not account for your full cardiovascular risk profile, and any concerns about cholesterol or heart disease risk should be discussed with a qualified healthcare provider.
Also known as
Friedewald formula calculatorLDL cholesterol calculatorcalculate LDL from total cholesterolLDL risk category calculatorbad cholesterol calculator