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Friedewald LDL Cholesterol Estimate

Estimate LDL with the historical fasting-lipid Friedewald relationship.

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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Use the result with context

Health results are educational estimates, not a diagnosis or treatment recommendation. A qualified clinician can interpret measurements in the context of your health.

Formula and method

Total cholesterol 200 mg/dL, HDL 50 mg/dL and triglycerides 150 mg/dL give estimated LDL 120 mg/dL.

LDL (mg/dL) = total cholesterol − HDL − triglycerides/5.

Worked example

Enter these known values and leave the other values blank.

Total cholesterol
200 mg/dL
High-density lipoproteins (HDL)
50 mg/dL
Triglycerides (TG)
150 mg/dL
Low-density lipoprotein (LDL)
120 mg/dL

Assumptions and limitations

  • For a fasting sample and triglycerides below 400 mg/dL. This historical approximation can be inaccurate even below that limit, particularly at low LDL or elevated triglycerides; it is not a direct LDL assay. Positive concentrations and a positive estimated LDL are required.
  • Use the displayed units and measurements from the same context. Editable fields support arithmetic inverses when enough independent values are supplied. Clear a preset value before solving it as an unknown.
  • This tool performs the stated arithmetic model. It does not establish a diagnosis, prescribe treatment or replace laboratory and clinical assessment.

Common questions

What does this calculation represent?

For a fasting sample and triglycerides below 400 mg/dL. This historical approximation can be inaccurate even below that limit, particularly at low LDL or elevated triglycerides; it is not a direct LDL assay. Positive concentrations and a positive estimated LDL are required.

Can I solve for a different field?

Clear the unknown field and enter enough independent values in the remaining editable controls. A relationship cannot recover a unique value when a dividing quantity is zero.

References

Bookify adds independently reviewed bounds: Friedewald estimation requires triglycerides below 400 mg/dL.

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