CalcLDL Cholesterol Calculator
LDL Cholesterol Calculator. Free online calculator with formula, examples and step-by-step guide.
LDL Cholesterol Calculator: Assess Your Lipid Profile
The LDL Cholesterol calculator estimates your low-density lipoprotein cholesterol level using the Friedewald equation, which derives LDL from a standard lipid panel without requiring direct measurement. This widely used formula provides a quick assessment of cardiovascular risk from routine blood test results.
Friedewald Equation
LDL = Total Cholesterol − HDL − (Triglycerides / 5)
All values are expressed in mg/dL. The term Triglycerides / 5 estimates very-low-density lipoprotein (VLDL) cholesterol, based on the observation that VLDL cholesterol is approximately one-fifth of the triglyceride level in fasting blood samples.
The Friedewald equation was published in 1972 and has been the standard method for estimating LDL cholesterol for over five decades. It is valid only for fasting samples (8–12 hours without food) and when triglyceride levels are below 400 mg/dL. Above this threshold, the VLDL estimation becomes inaccurate and direct LDL measurement is required.
Worked Examples
Example 1: Standard Lipid Panel
A patient's fasting lipid panel shows: Total Cholesterol = 220 mg/dL, HDL = 50 mg/dL, Triglycerides = 150 mg/dL.
Calculation: LDL = 220 − 50 − (150 / 5) = 220 − 50 − 30 = 140 mg/dL
An LDL of 140 mg/dL falls in the "near optimal or above optimal" range (130–159 mg/dL). Lifestyle modifications such as dietary changes and increased exercise would typically be recommended.
Example 2: Elevated Triglycerides
A patient presents with: Total Cholesterol = 260 mg/dL, HDL = 35 mg/dL, Triglycerides = 280 mg/dL.
Calculation: LDL = 260 − 35 − (280 / 5) = 260 − 35 − 56 = 169 mg/dL
An LDL of 169 mg/dL is classified as "high" (160–189 mg/dL). Combined with low HDL (below 40 mg/dL) and elevated triglycerides, this profile suggests increased cardiovascular risk that may warrant statin therapy discussion with a physician.
Common Uses
- Estimating LDL cholesterol from routine fasting lipid panel results in primary care
- Assessing cardiovascular disease risk during annual health check-ups
- Monitoring the effectiveness of cholesterol-lowering medications such as statins
- Screening for dyslipidemia in patients with diabetes, hypertension, or family history of heart disease
- Calculating the total cholesterol to HDL ratio (TC/HDL) for additional risk stratification
- Tracking lipid profile changes after dietary interventions or lifestyle modifications
Common Mistakes
- Using the Friedewald equation with non-fasting samples — triglyceride levels rise significantly after eating, invalidating the VLDL estimate
- Applying the formula when triglycerides exceed 400 mg/dL — the equation systematically underestimates LDL in this range
- Confusing mg/dL with mmol/L — the formula requires mg/dL; if your results are in mmol/L, multiply by 38.67 for cholesterol or 88.57 for triglycerides first
- Treating calculated LDL as equivalent to directly measured LDL — the Friedewald estimate can differ from direct measurement by 5–10 mg/dL
Pro Tip
Don't focus on LDL alone — look at your full lipid picture. The non-HDL cholesterol (Total Cholesterol − HDL) is increasingly recognized as a better predictor of cardiovascular risk than LDL alone, because it captures all atherogenic particles including LDL, VLDL, and IDL. Your non-HDL target should be about 30 mg/dL higher than your LDL target. For example, if your LDL goal is below 100 mg/dL, your non-HDL goal is below 130 mg/dL.
Frequently Asked Questions
Optimal LDL is below 100 mg/dL. Near optimal is 100–129 mg/dL. Borderline high is 130–159 mg/dL. High is 160–189 mg/dL. Very high is 190 mg/dL and above. Target levels may be lower for people with existing cardiovascular disease or diabetes.
Fast for 9–12 hours before your blood draw. You can drink water during this time. Avoid alcohol for 24 hours before the test, as it can significantly elevate triglyceride levels and affect the LDL calculation.
When triglycerides exceed 400 mg/dL, the Friedewald equation is not reliable. Your lab should perform a direct LDL measurement instead. Some laboratories now use the Martin-Hopkins equation or the Sampson equation, which are more accurate at higher triglyceride levels.
Adults aged 20 and older should have a lipid panel every 4–6 years if risk is low. If you have cardiovascular risk factors, diabetes, or are on cholesterol-lowering medication, testing every 3–12 months may be recommended based on your individual situation.