# LDL-C Calculator (Friedewald)

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.

> Canonical page: https://elysiatools.com/en/tools/ldl-calculator-friedewald

- **Category:** Health

- **Keywords:** LDL cholesterol, LDL-C, Friedewald, calculated LDL, lipid panel, total cholesterol, HDL, triglycerides, VLDL, familial hypercholesterolemia, cardiology, ASCVD, statin

## 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.

## Inputs

- **Unit System** (select)
- **Total Cholesterol** (number): Fasting total cholesterol. Use the unit selected under 'Unit System'.
- **HDL Cholesterol** (number): Fasting HDL-C. Use the unit selected under 'Unit System'.
- **Triglycerides** (number): Fasting triglycerides. Use the unit selected under 'Unit System'. Note: Friedewald is unreliable when TG ≥ 400 mg/dL (4.5 mmol/L).
- **Decimal Places** (number)

## 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

- Select the unit system: mg/dL or mmol/L.
- Enter fasting total cholesterol, HDL-C, and triglycerides in the selected unit.
- Optionally choose the number of decimal places for the result.
- The 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.

## Frequently asked questions

### 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.

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