LDL Cholesterol Calculator

What Does Calculated LDL Mean?

Low-density lipoprotein cholesterol, written as LDL-C, is the amount of cholesterol carried in LDL and related particles in a blood sample. A standard lipid panel measures total cholesterol, HDL-C and triglycerides. Many laboratories then estimate LDL-C with an equation instead of measuring it directly.

“LDL calculated” on a lab report therefore names the method, not a separate type of cholesterol. The value can support cardiovascular prevention decisions, but it is not a complete heart-risk score. Age, blood pressure, smoking, diabetes, kidney disease, family history and existing atherosclerotic cardiovascular disease can change what a result means for one person.

LDL Calculation Formula

The traditional Friedewald equation estimates very-low-density lipoprotein cholesterol from triglycerides, then subtracts that estimate and HDL-C from total cholesterol.

This version requires all values in mg/dL. In mmol/L, the equivalent divisor is commonly written as 2.2. This calculator converts inputs to mg/dL internally, applies each equation, and converts the answer back so unit mixing cannot silently alter the result.

The result is an estimate because the fixed triglyceride-to-VLDL relationship does not fit every sample. Error becomes more important with high triglycerides and at low LDL-C concentrations.

Sampson / NIH LDL Equation

The Sampson equation was developed from a large lipid database to improve calculated LDL-C, particularly when triglycerides are elevated. Its published equation is:

All terms in that equation use mg/dL, and non-HDL-C equals total cholesterol minus HDL-C. The original study reported validation for triglycerides up to 800 mg/dL. That broader range does not make every result definitive; direct measurement, repeat fasting testing or another validated laboratory method may still be appropriate.

The Martin/Hopkins method uses an adjustable triglyceride-to-VLDL factor selected from a lookup table. It can be valuable, but it is not reproduced here because it is not a single fixed equation. Use the exact method supplied by a validated laboratory or official tool.

High Triglycerides and LDL Calculator Limits

When triglycerides are high, the lipid panel and the reason for testing matter more than online arithmetic. The 2026 dyslipidemia guideline also notes that ApoB can add information when triglycerides exceed 200 mg/dL or achieved LDL-C is below 70 mg/dL.

LDL Calculator in mg/dL and mmol/L

United States laboratories commonly report lipids in mg/dL, while many other countries use mmol/L. Cholesterol and triglycerides require different conversion factors:

If an LDL result is 120 mg/dL, dividing by 38.67 gives about 3.10 mmol/L. Switching units in the calculator converts each populated field with its correct factor.

LDL Cholesterol Range and Treatment Goals

General educational tables often group adult LDL-C below 100 mg/dL as optimal, 100–129 as near or above optimal, 130–159 as borderline high, 160–189 as high and 190 mg/dL or higher as very high. These labels describe concentration bands; they do not determine one person’s treatment goal.

Current ACC/AHA guidance again uses risk-based LDL-C and non-HDL-C goals. For example, the 2026 guideline lists LDL-C below 55 mg/dL for very-high-risk secondary prevention and at least below 70 mg/dL for other people with established ASCVD. Primary-prevention decisions use overall risk and health conditions, not this number alone.

For an adult prevention estimate that includes multiple risk factors, use the site’s ASCVD Risk Calculator. It answers a different question from calculating LDL-C.

Non-HDL Cholesterol and LDL Ratios

Non-HDL-C subtracts HDL-C from total cholesterol. It represents cholesterol carried across a broader group of potentially atherogenic particles and does not require triglycerides in its formula.

The LDL/HDL and total cholesterol/HDL ratios are sometimes printed or discussed with a lipid profile. This calculator provides them as supporting numbers, but modern prevention decisions generally emphasize absolute atherogenic cholesterol, ApoB where appropriate and the person’s overall cardiovascular risk. A favorable ratio should not cancel out a high LDL-C result.

Direct LDL vs Calculated LDL

If calculated and direct results disagree, do not choose the more reassuring number. Confirm whether the sample was fasting, whether triglycerides were elevated, which method the laboratory used, and whether repeat testing is needed.

Does an LDL Calculation Require Fasting?

Many routine lipid profiles can be collected without fasting. A recent meal may raise triglycerides, however, and triglycerides directly affect calculated LDL equations. A clinician may request a repeat fasting panel when triglycerides are high, the result is unexpected or a specific diagnosis is being evaluated.

Use all inputs from the same collection. Do not combine a previous HDL value with today’s total cholesterol and triglycerides.

Common LDL Calculation Errors

• Mixing units: mg/dL and mmol/L cannot be placed in the same equation without conversion.
• Using the wrong triglyceride divisor: 5 applies to mg/dL and 2.2 to mmol/L in the Friedewald form.
• Using Friedewald at TG ≥400 mg/dL: this page intentionally suppresses that result.
• Comparing different samples: total cholesterol, HDL and triglycerides must come from the same lipid panel.
• Confusing LDL-C with particle count: LDL-C, ApoB and LDL particle measurements are related but not interchangeable.
• Treating a general range as a personal goal: established ASCVD, diabetes, kidney disease and overall risk can change targets.
• Assuming the formula diagnoses disease: only a qualified clinician can interpret the result in full context.