LDL Calculator

How LDL Is Calculated

LDL cholesterol is calculated with the mathematical formula total cholesterol − HDL cholesterol − (triglycerides ÷ 5), where all values use milligrams per deciliter (mg/dL). In 1972, Friedewald, Levy, and Fredrickson published this equation to estimate low-density lipoprotein cholesterol without using a preparative ultracentrifuge. According to MedlinePlus, an LDL value labelled calculated on a lab report represents an estimate derived from total cholesterol, high-density lipoprotein (HDL), and triglycerides. MedlinePlus notes that laboratories can also measure LDL directly from a blood sample.

For example, total cholesterol of 210 mg/dL, HDL of 50 mg/dL, and triglycerides of 150 mg/dL yields 210 − 50 − (150 ÷ 5) = 210 − 50 − 30 = 130 mg/dL. In the same example, non-HDL cholesterol equals total cholesterol minus HDL, which is 210 − 50 = 160 mg/dL. When triglycerides equal or exceed 400 mg/dL, the LDL calculator displays your non-HDL cholesterol along with a note that a directly measured LDL test is required. If your lab report lists numbers in millimoles per liter (mmol/L), the LDL calculator converts them before running the arithmetic. Total cholesterol, HDL, LDL, and non-HDL in mmol/L are multiplied by 38.67 to obtain mg/dL. Triglycerides in mmol/L are multiplied by 88.57 to obtain mg/dL. When you enter SI units, the calculator shows LDL and non-HDL cholesterol in both mg/dL and mmol/L.

Reading Your LDL and Non-HDL Results

The NHLBI ATP III guidelines sort a calculated LDL into five categories.

The NHLBI ATP III guidelines state that individuals should obtain a complete lipoprotein profile after a 9- to 12-hour fast. In the worked example with total cholesterol of 210 mg/dL, HDL of 50 mg/dL, and triglycerides of 150 mg/dL, the calculated LDL of 130 mg/dL falls into the borderline high tier of the ATP III classification.

The calculator also reports non-HDL cholesterol. According to MedlinePlus, healthy non-HDL cholesterol for adults is less than 130 mg/dL. MedlinePlus states that total cholesterol below 200 mg/dL is healthy for adults, while an HDL level of 60 mg/dL or higher is best. An HDL level below 40 mg/dL in men or below 50 mg/dL in women is considered low by MedlinePlus standards. Non-HDL cholesterol equals total cholesterol minus HDL cholesterol.

What the Calculator Does Not Tell You

The LDL calculator does not diagnose medical conditions and does not estimate heart risk. The LDL calculator also does not state individual treatment targets, does not evaluate prescription medications, and does not provide dietary or supplement advice. The calculation runs entirely inside your web browser. The calculator is free to use.

A calculated LDL is an indirect estimate based on total cholesterol, HDL, and triglycerides. The calculator does not use the Friedewald method to calculate LDL when triglycerides equal or exceed 400 mg/dL (4.5 mmol/L). In those situations, a directly measured LDL is needed. The lipid panel guide details what a lipid panel measures and whether to fast. The cholesterol levels guide lists cholesterol ranges by age in mg/dL and mmol/L. The TyG index calculator covers the triglyceride-glucose index from the same fasting draw.

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