What is the Friedewald equation?

The Friedewald equation estimates LDL as: LDL = Total Cholesterol - HDL - (Triglycerides / 5) in mg/dL, or LDL = Total Cholesterol - HDL - (Triglycerides / 2.2) in mmol/L. It was published in 1972 and remains the most widely used method for estimating LDL from a standard lipid panel.

When is this calculation not accurate?

The Friedewald equation is unreliable when triglycerides exceed 400 mg/dL (4.5 mmol/L). Very high triglycerides cause the VLDL estimate to be inaccurate. In those cases, a direct LDL measurement is required.

What is a healthy LDL level?

General guidelines consider LDL below 100 mg/dL (2.59 mmol/L) as optimal. Levels between 100–129 mg/dL are near optimal, 130–159 mg/dL borderline high, 160–189 mg/dL high, and 190 mg/dL or above very high. Target ranges may differ based on individual cardiovascular risk — consult your doctor.

What is the difference between LDL and HDL?

LDL (low-density lipoprotein) carries cholesterol to the arteries and is associated with cardiovascular risk when elevated. HDL (high-density lipoprotein) carries cholesterol away from the arteries back to the liver and is associated with lower cardiovascular risk.

Is this tool a substitute for medical advice?

No. This calculator provides an educational estimate only. Always consult a qualified healthcare professional to interpret your lipid panel and determine appropriate treatment.

LDL Cholesterol Calculator

Name: LDL Cholesterol Calculator
Availability: InStock
Author: Nham Vu

Enter your total cholesterol, HDL, and triglycerides to estimate your LDL using the Friedewald equation.

Lipid Panel Values

All values from a standard blood test (fasting lipid panel).

Unit

Total Cholesterol (mg/dL)

HDL Cholesterol (mg/dL)

Triglycerides (mg/dL)

Enter your lipid values and click Calculate LDL.

LDL Reference Ranges

Optimal < 100 mg/dL / < 2.59 mmol/L

Near Optimal 100–129 mg/dL / 2.59–3.34 mmol/L

Borderline High 130–159 mg/dL / 3.37–4.12 mmol/L

High 160–189 mg/dL / 4.14–4.90 mmol/L

Very High ≥ 190 mg/dL / ≥ 4.92 mmol/L

Source: American Heart Association / NCEP ATP III guidelines. Consult your physician for personalized targets.

Summary

Enter your total cholesterol, HDL, and triglycerides to estimate your LDL using the Friedewald equation.

How it works

Select your preferred unit — mg/dL (US standard) or mmol/L (international).
Enter your total cholesterol value from your lipid panel report.
Enter your HDL (high-density lipoprotein) cholesterol value.
Enter your triglycerides value.
Click Calculate to see your estimated LDL and its cardiovascular risk category.
Review the color-coded result and the standard reference ranges below.

Use cases

Estimate LDL when a direct LDL measurement is not available.
Cross-check a reported LDL against your raw lipid panel numbers.
Track changes in estimated LDL over time as you adjust diet or medication.
Understand where your cholesterol falls on standard cardiovascular risk scales.
Quickly convert between mg/dL and mmol/L for international lab reports.
Educate patients on how LDL is derived from a routine lipid panel.

Frequently Asked Questions

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Last updated: 2026-05-23 · Reviewed by Nham Vu