The Complete Guide to Lipid Profile Calculation Formulas

Ever looked at your lab report and wondered how the numbers are actually calculated? While some values like Total Cholesterol and HDL are measured directly, others, most notably LDL-C, are often estimated using specific formulas. This guide breaks down the essential formulas used in your lipid profile calculation, from the famous Friedewald equation to key risk ratios.

1. The Core Formula: Calculating LDL-C (Friedewald Equation)

The most common formula for lipid profile estimation is the Friedewald equation. It is used to estimate Low-Density Lipoprotein (LDL-C) cholesterol when it has not been measured directly. This calculation is valid only for fasting lipid profile calculation, as high triglycerides after a meal will make it inaccurate.

The Friedewald Formula:

For mg/dL:
LDL-C = [Total Cholesterol] – [HDL-C] – ([Triglycerides] / 5) For mmol/L:
LDL-C = [Total Cholesterol] – [HDL-C] – ([Triglycerides] / 2.2)

The `(Triglycerides / 5)` or `(Triglycerides / 2.2)` part is used as an estimate for VLDL (Very Low-Density Lipoprotein) cholesterol. This formula is generally considered unreliable if Triglyceride levels are above 400 mg/dL (4.5 mmol/L).

2. A Modern Metric: Non-HDL Cholesterol Formula

Many experts now prefer using Non-HDL Cholesterol because it represents the total concentration of all “bad” atherogenic lipoproteins (including LDL and VLDL). Its calculation is simple and is accurate even in a non-fasting state.

The Non-HDL Formula:

Non-HDL-C = [Total Cholesterol] – [HDL-C]

3. Calculating Key Risk Ratios

Beyond individual numbers, the ratios between lipids are powerful indicators of cardiovascular risk. These are simple division calculations.

• TC/HDL Ratio: [Total Cholesterol] / [HDL-C]
• LDL/HDL Ratio: [LDL-C] / [HDL-C]
• TG/HDL Ratio: [Triglycerides] / [HDL-C]

To instantly find your personal ratios and see what they mean, use our Free Lipid Profile Ratio Calculator.

4. Lipid Profile Calculation Chart (Reference Ranges)

These formulas give you a number. This chart helps you understand what that number means. These ranges are based on the NCEP ATP III guidelines for adults.

Lipid Component	Category	Range (mg/dL)	Range (mmol/L)
Total Cholesterol	Desirable	< 200	< 5.2
	Borderline High	200 – 239	5.2 – 6.2
	High	≥ 240	≥ 6.2
LDL-C (“Bad”)	Optimal	< 100	< 2.6
	Near Optimal	100 – 129	2.6 – 3.3
	Borderline High	130 – 159	3.4 – 4.1
	High / Very High	≥ 160	≥ 4.1
HDL-C (“Good”)	Low (Risk Factor)	< 40	< 1.0
	High (Protective)	≥ 60	≥ 1.6
Triglycerides	Normal	< 150	< 1.7
	Borderline High	150 – 199	1.7 – 2.2
	High	≥ 200	≥ 2.3

5. Converting Units (mg/dL vs. mmol/L)

If your lab report uses different units than the formula you’re using, you’ll need to convert them first. For example, the Friedewald equation `(TG / 5)` is only for `mg/dL`. For `mmol/L`, the denominator is `2.2`. To avoid manual errors, it’s best to use a dedicated tool.

To instantly convert all your lab values, use our Lipid Profile Unit Conversion Calculator.

Beyond the Formulas: Assessing Your Real Risk

These formulas are just the beginning. Your personal cardiovascular risk is much more complex, factoring in your age, sex, blood pressure, smoking status, and other health conditions. This is where a comprehensive risk assessment comes in.

To see how your numbers fit into the bigger picture, use our main Lipid Profile & Risk Assessment Calculator.

References

• Friedewald, W. T., Levy, R. I., & Fredrickson, D. S. (1972). Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge. Clinical chemistry, 18(6), 499-502.
• National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). (2002). Final Report. Circulation, 106(25), 3143-3421.
• Goff, D. C., Jr., et al. (2013). 2013 ACC/AHA Guideline on the Assessment of Cardiovascular Risk. Journal of the American College of Cardiology, 63(25_PA), 2935-2959.

Important Disclaimer

This information and the risk assessments provided by our tool are for educational purposes only and should not be considered medical advice, diagnosis, or treatment. Always consult with a qualified healthcare provider for the interpretation of your personal health data and for any health concerns or before making any decisions related to your health or treatment.