LDL Calculator

Written by Great Medico

Updated September 24, 2026 •2 min read

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Lab and glucose-related numbers are easier to use when the conversion or equation is transparent. LDL Calculator keeps the calculation focused on the values you enter.

What this calculator does

Calculated LDL can be estimated from a standard lipid panel when direct LDL measurement is not being used. This calculator applies the classic Friedewald relationship to total cholesterol, HDL, and triglycerides. Metabolic calculations can add context to measurements, but laboratory timing, assay methods, medications, and the clinical situation can change what the result means.

How to use it

Enter or select Total cholesterol, HDL cholesterol, and Triglycerides. Use the units offered by the calculator and keep measurements consistent when you plan to compare results over time.

How the calculation works

With values in mg/dL, LDL = total cholesterol − HDL − triglycerides ÷ 5. The current calculator accepts triglycerides within its implemented 100–400 mg/dL validation range before applying the equation.

Example

For the sample values prefilled in this calculator, the primary result is 120 mg/dL (Friedewald LDL cholesterol). This example is there to show how the inputs flow through the implemented equation; replace the sample values with your own measurements before using the result.

How to interpret the result

The output is an estimated LDL concentration, not a direct assay. It is most useful when the lipid sample and triglyceride level are appropriate for the Friedewald approach.

Limitations and notes

Friedewald LDL becomes less reliable as triglycerides rise and can differ from newer equations or direct measurement, especially at low LDL levels. This implementation also enforces its own triglyceride range, so a rejected value does not mean LDL can never be estimated clinically by another validated method. When laboratory values are involved, use results from the same units and note whether the sample was fasting or taken under other specified conditions. A mathematically correct result can still be clinically misleading when the underlying test or timing is inappropriate.