Friedewald becomes inaccurate when triglycerides are high or LDL is very low, and labs may use direct measurement or newer equations. Numbers vary from day to day and with illness or diet. Targets differ by risk category, and treatment decisions use more than the cholesterol alone.
This is not a diagnosis.
Enter total cholesterol, HDL cholesterol and triglycerides in milligrams per deciliter from a lipid panel, ideally fasting for the most accurate LDL. The Friedewald equation estimates LDL as total cholesterol minus HDL minus triglycerides divided by 5, and it is valid only when triglycerides are below 400 mg/dL. Take the numbers from your lab report, which may already list a calculated or measured LDL.
Cholesterol (LDL): worked example
| Total cholesterol (mg/dL) | 200 |
|---|---|
| HDL cholesterol (mg/dL) | 50 |
| Triglycerides (mg/dL) | 150 |
| Estimated LDL (mg/dL) | 120 |
| Non-HDL cholesterol (mg/dL) | 150 |
| Total-to-HDL ratio | 4.00× |
Cholesterol (LDL): formula
Common error: Treating a calculated LDL as a diagnosis. It is an estimate, it can drift from a direct measurement, and targets depend on your other risk factors.
Cholesterol (LDL): changing Total cholesterol (mg/dL)
| Total cholesterol (mg/dL) | Estimated LDL (mg/dL) | Non-HDL cholesterol (mg/dL) | Total-to-HDL ratio |
|---|---|---|---|
| 160 | 80 | 110 | 3.20× |
| 180 | 100 | 130 | 3.60× |
| 200 (example) | 120 | 150 | 4.00× |
| 220 | 140 | 170 | 4.40× |
| 240 | 160 | 190 | 4.80× |
Cholesterol (LDL): compare input ranges
| Input | Tested from | To | Estimated LDL (mg/dL): low input | Estimated LDL (mg/dL): high input | Swing |
|---|---|---|---|---|---|
| Total cholesterol (mg/dL) | 180 | 220 | 100 | 140 | 40 (33%) |
| HDL cholesterol (mg/dL) | 45 | 55 | 125 | 115 | 10 (8.3%) |
| Triglycerides (mg/dL) | 135 | 165 | 123 | 117 | 6 (5.0%) |
Cholesterol (LDL): individual input comparisons
| Input | Value | Estimated LDL (mg/dL) | Non-HDL cholesterol (mg/dL) | Total-to-HDL ratio |
|---|---|---|---|---|
| Total cholesterol (mg/dL) | 160 | 80 | 110 | 3.20× |
| 180 | 100 | 130 | 3.60× | |
| 200 | 120 | 150 | 4.00× | |
| 220 | 140 | 170 | 4.40× | |
| 240 | 160 | 190 | 4.80× | |
| HDL cholesterol (mg/dL) | 40 | 130 | 160 | 5.00× |
| 45 | 125 | 155 | 4.44× | |
| 50 | 120 | 150 | 4.00× | |
| 55 | 115 | 145 | 3.64× | |
| 60 | 110 | 140 | 3.33× | |
| Triglycerides (mg/dL) | 120 | 126 | 150 | 4.00× |
| 135 | 123 | 150 | 4.00× | |
| 150 | 120 | 150 | 4.00× | |
| 165 | 117 | 150 | 4.00× | |
| 180 | 114 | 150 | 4.00× |
Cholesterol (LDL): combined input changes
| Total cholesterol (mg/dL) / HDL cholesterol (mg/dL) | 40 | 50 | 60 |
|---|---|---|---|
| 160 | 90 | 80 | 70 |
| 180 | 110 | 100 | 90 |
| 200 | 130 | 120 | 110 |
| 220 | 150 | 140 | 130 |
| 240 | 170 | 160 | 150 |
Cholesterol (LDL): which assumptions move the result?
Cholesterol (LDL): values and definitions
| Quantity and definition | Value used |
|---|---|
| Total cholesterol (mg/dL) | 200 |
| HDL cholesterol (mg/dL) | 50 |
| Triglycerides (mg/dL) — The Friedewald formula is not valid at 400 mg/dL or above. | 150 |
| Estimated LDL (mg/dL) | 120 |
| Non-HDL cholesterol (mg/dL) | 150 |
| Total-to-HDL ratio | 4.00× |
Cholesterol (LDL): half and double Total cholesterol (mg/dL)
| Total cholesterol (mg/dL) | Estimated LDL (mg/dL) |
|---|---|
| 100 | 20 |
| 200 | 120 |
| 400 | 320 |
Clinical Estimates calculators: Mean Arterial Pressure Calculator, IVF Due Date Calculator, Period Calculator, GFR Calculator, BAC Calculator, Creatinine Clearance Calculator.
Most lab reports estimate LDL from three measured numbers instead of measuring it directly. The Friedewald formula subtracts HDL and one fifth of triglycerides from total cholesterol, so 200 total, 50 HDL and 150 triglycerides give an LDL of 120. Non-HDL cholesterol adds a broader view of all the artery-clogging particles, and the total-to-HDL ratio compresses the panel into one number.
The Friedewald estimate is not valid when triglycerides are 400 mg/dL or higher.
See related risks on the blood pressure and mean arterial pressure pages, and body measures on the BMI and waist-to-hip ratio calculators. The macronutrient and fat intake pages show dietary levers, such as reducing saturated fat. A clinician decides on medication.
What is a healthy LDL level?
Below 100 mg/dL is considered optimal for most people, and goals are lower for people at high risk of heart disease. Your clinician sets your target.
What is non-HDL cholesterol?
Total cholesterol minus HDL, which includes all the potentially artery-clogging particles, and it is a useful marker especially when triglycerides are high.
Do I need to fast for a lipid test?
Fasting is no longer always required, but it can improve the accuracy of the LDL estimate, especially when triglycerides are elevated.