LDL Cholesterol Calculator · Friedewald

LDL Cholesterol Calculator

Estimate your LDL cholesterol using the Friedewald equation.

Lipid Panel
Units:
mg/dL
mg/dL
mg/dL
Friedewald Equation: LDL = Total − HDL − (Triglycerides / 5) [mg/dL]
For mmol/L: LDL = Total − HDL − (Triglycerides / 2.2). Valid for TG < 400 mg/dL.
LDL Result
✅ Optimal
Optimal Near Opt. Borderline High Very High
LDL Cholesterol: — mg/dL
Your LDL level is within optimal range.
📊 LDL
—
📈 Total/HDL
—
📉 Risk Category
—
🔬 Formula
Friedewald
💡 Interpretation
Enter your lipid values to calculate your LDL cholesterol.
📋 LDL Classification (mg/dL)
Optimal: < 100 Near optimal: 100 – 129 Borderline: 130 – 159 High: 160 – 189 Very high: ≥ 190 Note: For mmol/L divide by 38.67

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Faiq Ur Rahman

Founder & CEO, Toolraxy

Faiq Ur Rahman is a web designer, digital product developer, and founder of Toolraxy, a growing platform of web-based calculators and utility tools. He specializes in building structured, user-friendly tools focused on health, finance, productivity, and everyday problem-solving.

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What Is LDL Cholesterol?

LDL (low-density lipoprotein) cholesterol is often called “bad” cholesterol because high levels can lead to the buildup of plaque in your arteries,  a condition called atherosclerosis. This plaque narrows and stiffens arteries, reducing blood flow and increasing the risk of heart attack, stroke, and peripheral artery disease. LDL particles carry cholesterol from the liver to cells throughout the body, but when there’s more LDL than cells can use, the excess cholesterol can deposit in artery walls. Managing LDL levels is one of the most important steps in preventing cardiovascular disease. The Friedewald equation provides a reliable estimate of LDL from routine lipid panel components.

How to Use the LDL Cholesterol Calculator

  1. Select your preferred unit (mg/dL or mmol/L) using the toggle buttons at the top of the calculator.

  2. Enter your Total Cholesterol in the first input field.

  3. Enter your HDL Cholesterol in the second input field.

  4. Enter your Triglycerides in the third input field.

  5. Use the quick example buttons to test common lipid profile scenarios.

  6. Click the Calculate button (or simply wait, results update automatically).

  7. View your calculated LDL Cholesterol level with the appropriate unit.

  8. Check your risk classification with a color-coded badge (Optimal, Near Optimal, Borderline, High, Very High).

  9. Review your Total/HDL Ratio and overall Risk Category in the results grid.

  10. Read the personalized interpretation for actionable guidance on your LDL level.

  11. Copy, share, or embed your results using the buttons below.

 

How the LDL Cholesterol Calculator Formula Works

The calculator uses the Friedewald equation, which is the standard formula for estimating LDL cholesterol from a routine lipid panel.

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

Formula (mmol/L): LDL = Total Cholesterol − HDL Cholesterol − (Triglycerides ÷ 2.2)

Note: The Friedewald equation is considered valid when triglycerides are below 400 mg/dL (4.5 mmol/L). For higher triglyceride levels, the equation becomes less accurate, and direct LDL measurement is recommended.

LDL Classification (ATP III Guidelines):

  • Optimal: LDL < 100 mg/dL (< 2.59 mmol/L)

  • Near Optimal: LDL 100–129 mg/dL (2.59–3.34 mmol/L)

  • Borderline: LDL 130–159 mg/dL (3.36–4.11 mmol/L)

  • High: LDL 160–189 mg/dL (4.14–4.89 mmol/L)

  • Very High: LDL ≥ 190 mg/dL (≥ 4.91 mmol/L)

The calculator also computes the Total/HDL ratio, a strong predictor of cardiovascular risk, with lower ratios indicating better risk profiles.

 

Worked Example

Dr. Chen’s patient has the following lipid panel results:

  • Total Cholesterol: 220 mg/dL

  • HDL Cholesterol: 50 mg/dL

  • Triglycerides: 160 mg/dL

Step 1 — Apply the Friedewald equation:
LDL = Total − HDL − (Trig ÷ 5)
LDL = 220 − 50 − (160 ÷ 5)
LDL = 220 − 50 − 32
LDL = 138 mg/dL

Step 2 — Classify the result:
138 mg/dL falls in the Borderline range (130–159 mg/dL).

Step 3 — Total/HDL Ratio:
Total/HDL = 220 ÷ 50 = 4.40

Step 4 — Interpretation:
“Your LDL is borderline high (138 mg/dL). Discuss with your doctor about lifestyle changes and possible medication.”

Dr. Chen discusses this result with the patient, recommending increased physical activity, a Mediterranean diet, and follow-up testing in 3–6 months. The patient’s cardiovascular risk factors (age, blood pressure, smoking status) will also be considered in the overall risk assessment.

Frequently Asked Questions

What is the LDL Cholesterol Calculator and how does it work?

The LDL Cholesterol Calculator is a tool that estimates your LDL cholesterol using the Friedewald equation. It works by subtracting your HDL cholesterol and one-fifth of your triglycerides (in mg/dL) from your total cholesterol. For mmol/L, the factor is one-2.2. The calculator provides immediate classification and interpretation based on ATP III guidelines.

 

What is the Friedewald equation?

The Friedewald equation is a formula used to estimate LDL cholesterol from a routine lipid panel. In mg/dL: LDL = Total − HDL − (Trig ÷ 5). In mmol/L: LDL = Total − HDL − (Trig ÷ 2.2). It was developed by William Friedewald in 1972 and remains the standard method for estimating LDL in clinical practice.

 

What is a normal LDL cholesterol level?

Normal LDL depends on your risk profile. According to ATP III guidelines: Optimal is < 100 mg/dL, Near Optimal is 100–129 mg/dL, Borderline is 130–159 mg/dL, High is 160–189 mg/dL, and Very High is ≥ 190 mg/dL. For high-risk individuals, targets may be even lower (< 70 mg/dL).

 

What is the limitation of the Friedewald equation?

The Friedewald equation is less accurate when triglycerides exceed 400 mg/dL (4.5 mmol/L). In these cases, the formula can underestimate LDL. It also assumes a constant ratio of VLDL to triglycerides, which may not hold in some populations. For very low LDL levels (< 70 mg/dL), direct measurement may be more accurate.

 

Can I use this calculator if my triglycerides are high?

The calculator will still provide an estimate, but the Friedewald equation is validated for triglycerides below 400 mg/dL. If your triglycerides exceed this threshold, consider asking your healthcare provider about direct LDL measurement for a more accurate result.

 

What is the difference between calculated and measured LDL?

Calculated LDL uses the Friedewald equation to estimate LDL from Total, HDL, and Triglycerides. Measured LDL is obtained through direct laboratory testing. Calculated LDL is adequate for most clinical purposes when triglycerides are normal, but direct measurement may be preferred in certain situations (e.g., high triglycerides, very low LDL, or when treatment decisions are critical).

 

What is the Total/HDL ratio and why does it matter?

The Total/HDL ratio compares total cholesterol to HDL cholesterol. It’s a strong predictor of cardiovascular risk, higher ratios indicate greater risk. An optimal ratio is below 3.5 for men and below 3.0 for women. The calculator includes this ratio as additional cardiovascular risk context.

 

How often should I check my LDL cholesterol?

For most adults, screening every 4–6 years is recommended. If you have risk factors (diabetes, hypertension, family history, or known cardiovascular disease), more frequent screening may be appropriate. Consult your healthcare provider for personalized recommendations.

 

Is this calculator suitable for children?

The Friedewald equation can be used for children, but pediatric LDL reference ranges differ from adult values. Consultation with a pediatrician or specialist is recommended for interpreting results in children and adolescents.

 

Can I use this calculator if I’m already on statins?

Yes, the calculator works for all individuals regardless of medication status. However, your LDL target may be lower if you’re on statins or at high risk. The calculator provides general classification, but your healthcare provider will have specific targets based on your overall risk profile.

Medical Disclaimer

This LDL Cholesterol Calculator is provided for educational and informational purposes only. It does not constitute medical advice, diagnosis, or treatment recommendations. The results are estimates based on the Friedewald equation and the values you enter, but they should not replace professional medical evaluation, including physical examination, comprehensive laboratory testing, and personalized care. The Friedewald equation has limitations and may not be accurate in all circumstances. Always consult with a qualified healthcare provider regarding your cardiovascular health, including the interpretation of your lipid panel results and the development of a treatment plan. No calculator can substitute for proper medical assessment and personalized care. Individual cardiovascular risk depends on many factors beyond LDL cholesterol, including age, sex, blood pressure, smoking status, and family history.

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