Calculate LDL-C (low-density lipoprotein cholesterol) indirectly with the Friedewald formula. In mg/dL: LDL-C = Total Cholesterol − HDL-C − (Triglycerides / 5); in mmol/L: LDL-C = TC − HDL-C − (TG / 2.2). Unreliable when triglycerides ≥ 400 mg/dL (4.5 mmol/L), in the non-fasting state, in type III dysbetalipoproteinemia, and at very low LDL-C (< 70 mg/dL). Treatment thresholds (ACC/AHA 2018): < 70 mg/dL (1.8 mmol/L) high-risk secondary prevention; < 100 mg/dL (2.6 mmol/L) moderate-risk / diabetes primary prevention; ≥ 190 mg/dL (4.9 mmol/L) suggests familial hypercholesterolemia. Unit system selectable: mg/dL or mmol/L. Derived from Friedewald 1972, Martin 2013, Sampson 2020, and ACC/AHA 2018. Not medical advice.
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Tool usage guide
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Key facts
Category
Health
Input types
select, number
Output type
json
Sample coverage
4
API ready
Yes
Overview
The LDL-C Calculator uses the Friedewald formula to estimate low-density lipoprotein cholesterol from fasting total cholesterol, HDL-C, and triglycerides. Choose mg/dL or mmol/L to receive a calculated LDL-C value, unit, category, and formula used. This tool is not medical advice.
When to use
Estimate LDL-C when you have fasting total cholesterol, HDL-C, and triglyceride results.
Convert a lipid panel into either mg/dL or mmol/L-based LDL-C calculations.
Review a calculated LDL-C value alongside general ACC/AHA threshold categories.
How it works
1Select the unit system: mg/dL or mmol/L.
2Enter fasting total cholesterol, HDL-C, and triglycerides in the selected unit.
3Optionally choose the number of decimal places for the result.
4The calculator applies Friedewald's formula and returns LDL-C, its unit, a category, and the calculation method.
Use cases
Quickly estimate LDL-C from a fasting lipid panel.
Check LDL-C calculations in mg/dL or mmol/L for study and educational workflows.
Compare a calculated value with broad LDL-C categories and treatment thresholds.
Examples
1. Typical lipid panel in mg/dL
Primary care learner
Background
A learner has fasting lipid results of total cholesterol 220 mg/dL, HDL-C 45 mg/dL, and triglycerides 150 mg/dL.
Problem
They want to calculate LDL-C and review the resulting category.
How to use
Select mg/dL, enter 220 for total cholesterol, 45 for HDL-C, and 150 for triglycerides. Set decimal places to 1.
The calculator returns LDL-C = 145 mg/dL and identifies it as LDL-C borderline high.
2. Lipid panel in SI units
Health sciences student
Background
A lipid panel reports total cholesterol of 5.7 mmol/L, HDL-C of 1.2 mmol/L, and triglycerides of 1.7 mmol/L.
Problem
The student needs an LDL-C estimate without converting the values to mg/dL.
How to use
Select mmol/L, enter 5.7 for total cholesterol, 1.2 for HDL-C, and 1.7 for triglycerides. Set decimal places to 2.
FAQ
What formula does this LDL-C calculator use?
It uses LDL-C = total cholesterol − HDL-C − triglycerides/5 in mg/dL, or LDL-C = TC − HDL-C − TG/2.2 in mmol/L.
What information do I need?
Enter fasting total cholesterol, HDL-C, and triglycerides, then select the matching unit system.
When is the Friedewald calculation unreliable?
It is unreliable when triglycerides are at least 400 mg/dL (4.5 mmol/L), in a non-fasting state, with type III dysbetalipoproteinemia, and at very low LDL-C below 70 mg/dL.
Can I use mg/dL and mmol/L values together?
No. All cholesterol and triglyceride values must use the unit system selected in the calculator.
Is this calculator medical advice?
No. It provides an indirect LDL-C estimate and should not replace professional interpretation of laboratory results.