Answer first
What this calculator tells you
Estimate LDL, non-HDL cholesterol and the total-to-HDL ratio from a standard lipid panel. Read a panel alongside your clinician's targets, which depend on your history. Formula: Friedewald LDL = total − HDL − triglycerides ÷ 5 (mg/dL, valid below 400 mg/dL triglycerides); non-HDL = total − HDL; ratio = total ÷ HDL. At the worked-example inputs, the estimated LDL (mg/dl) is 120. Holding every other input steady, moving total cholesterol (mg/dl) from 160 to 240 moves the result from 80 to 160.
Transparent method
The formula
Read a panel alongside your clinician's targets, which depend on your history.
Worked example
Example inputs
How to interpret the result
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.
At the worked-example inputs the estimated LDL (mg/dl) is 120. It rises with total cholesterol (mg/dl) and falls as HDL cholesterol (mg/dl) and triglycerides (mg/dl) increase.
A calculated value from a lab panel or a blood pressure reading is an educational estimate, not a diagnosis. Targets depend on your age, history and other risk factors, so use the numbers your own clinician sets, and never change a medicine or a plan because of a calculator.
Before you rely on it
What to check
Check the triglycerides. The formula stops being valid at 400 mg/dL, and the page shows a dash there instead of a misleading number.
The common error
Where people go wrong with cholesterol (LDL) calculator
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.
Sensitivity evidence
How total cholesterol (mg/dl) changes the estimated LDL (mg/dl)
Holding every other input at the worked-example value, moving total cholesterol (mg/dl) from 160 to 240 moves the estimated LDL (mg/dl) from 80 to 160: a spread of 80, or 67% of the worked-example result.
| 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× |
| 200worked example | 120 | 150 | 4.00× |
| 220 | 140 | 170 | 4.40× |
| 240 | 160 | 190 | 4.80× |
Every input, tested
Which input moves the estimated LDL (mg/dl) most
Of the 3 inputs, total cholesterol (mg/dl) moves the estimated LDL (mg/dl) most (40 across the range tested) and triglycerides (mg/dl) moves it least (6).
| Input | Tested from | To | Estimated LDL (mg/dL) at each end | Swing |
|---|---|---|---|---|
| Total cholesterol (mg/dL) | 180 | 220 | 100 to 140 | 40 (33%) |
| HDL cholesterol (mg/dL) | 45 | 55 | 125 to 115 | 10 (8.3%) |
| Triglycerides (mg/dL) | 135 | 165 | 123 to 117 | 6 (5.0%) |
Two variables at once
Estimated LDL (mg/dL) by total cholesterol (mg/dl) and HDL cholesterol (mg/dl)
Across the grid the estimated LDL (mg/dl) runs from 70 to 170. Moving total cholesterol (mg/dl) from 160 to 240 shifts it by 80 at the middle column, and moving HDL cholesterol (mg/dl) from 40 to 60 shifts it by 20 at the middle row, so total cholesterol (mg/dl) is the bigger lever here.
| 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 |
The highlighted cell is the worked example: 120.
Step by step
The worked example, input by input
| Input | Value used | What it means |
|---|---|---|
| Total cholesterol (mg/dL) | 200 | Enter the total cholesterol (mg/dl) used in this calculation. |
| HDL cholesterol (mg/dL) | 50 | Enter the HDL cholesterol (mg/dl) used in this calculation. |
| Triglycerides (mg/dL) | 150 | The Friedewald formula is not valid at 400 mg/dL or above, and the page shows a dash there. |
| Estimated LDL (mg/dL) | 120 | |
| Non-HDL cholesterol (mg/dL) | 150 | |
| Total-to-HDL ratio | 4.00× | |
Inputs, definitions and assumptions
Total cholesterol (mg/dL)
Enter the total cholesterol (mg/dl) used in this calculation. The prefilled worked-example value is 200.
HDL cholesterol (mg/dL)
Enter the HDL cholesterol (mg/dl) used in this calculation. The prefilled worked-example value is 50.
Triglycerides (mg/dL)
The Friedewald formula is not valid at 400 mg/dL or above, and the page shows a dash there. The prefilled worked-example value is 150.
How to use this calculator
- 1Verify the inputs. Gather total cholesterol (mg/dl), HDL cholesterol (mg/dl) and triglycerides (mg/dl) from your own documents; the prefilled values are examples.
- 2Save a baseline. The worked example puts the estimated LDL (mg/dl) at 120. Store your own version of it as Scenario A.
- 3Test one change. Start with total cholesterol (mg/dl), the input with the biggest effect here: moving total cholesterol (mg/dl) from 180 to 220 takes the estimated LDL (mg/dl) from 100 to 140, a swing of 33% of the worked-example figure.
- 4Check the extremes. At half the example total cholesterol (mg/dl) (100) the estimated LDL (mg/dl) is 20; at double (400) it is 320.
People also ask
Frequently asked questions
How do you calculate cholesterol (LDL)?
Friedewald LDL = total − HDL − triglycerides ÷ 5 (mg/dL, valid below 400 mg/dL triglycerides); non-HDL = total − HDL; ratio = total ÷ HDL. At the worked-example inputs the estimated LDL (mg/dl) is 120.
What does the cholesterol (LDL) result mean?
Read a panel alongside your clinician's targets, which depend on your history. At the worked-example inputs the estimated LDL (mg/dl) is 120. It rises with total cholesterol (mg/dl) and falls as HDL cholesterol (mg/dl) and triglycerides (mg/dl) increase.
How much does total cholesterol (mg/dl) change the estimated LDL (mg/dl)?
Holding every other input at the worked-example value, moving total cholesterol (mg/dl) from 160 to 240 moves the estimated LDL (mg/dl) from 80 to 160, a spread of 80.
What are the limits of this cholesterol (LDL) calculator?
A calculated value from a lab panel or a blood pressure reading is an educational estimate, not a diagnosis. Targets depend on your age, history and other risk factors, so use the numbers your own clinician sets, and never change a medicine or a plan because of a calculator. The tables on this page test total cholesterol (mg/dl) only from 160 to 240; a value outside that range is not tabulated here.
Which input moves the estimated LDL (mg/dl) most in the cholesterol (LDL) calculator?
Ranked by how far each moves the estimated LDL (mg/dl) across the range tested: total cholesterol (mg/dl) (40, 33%), HDL cholesterol (mg/dl) (10, 8.3%) and triglycerides (mg/dl) (6, 5.0%).
If I double total cholesterol (mg/dl) in the cholesterol (LDL) calculator, does the estimated LDL (mg/dl) double?
Doubling it from 200 to 400 takes the estimated LDL (mg/dl) from 120 to 320, which is 2.67 times the worked-example figure. So the result grows faster than the input does. Halving it to 100 gives 20.
How much does HDL cholesterol (mg/dl) matter in the cholesterol (LDL) calculator?
The worked example uses 50. With the other inputs left at the worked example, moving HDL cholesterol (mg/dl) from 45 to 55 takes the estimated LDL (mg/dl) from 125 to 115, a swing of 8.3% of the worked-example figure.
How much does triglycerides (mg/dl) matter in the cholesterol (LDL) calculator?
The worked example uses 150. With the other inputs left at the worked example, moving triglycerides (mg/dl) from 135 to 165 takes the estimated LDL (mg/dl) from 123 to 117, a swing of 5.0% of the worked-example figure.
Which inputs change the non-HDL cholesterol (mg/dl) in the cholesterol (LDL) calculator?
At the worked-example inputs it is 150. Total cholesterol (mg/dl) takes it from 130 to 170 and HDL cholesterol (mg/dl) takes it from 155 to 145.
Which inputs change the total-to-HDL ratio in the cholesterol (LDL) calculator?
At the worked-example inputs it is 4.00×. Total cholesterol (mg/dl) takes it from 3.60× to 4.40× and HDL cholesterol (mg/dl) takes it from 4.44× to 3.64×.
Can a calculator replace a lab test or a doctor's visit?
No. It gives an educational estimate from the numbers you enter. Only a clinician can read them alongside your history, symptoms and other tests.
Why can a calculated value differ from what my lab reports?
A lab may measure directly where a formula estimates, use a different method or reference range, or round differently. When the two disagree, go with the lab and ask your clinician.
How far ahead can a period be predicted?
The next period is the most reliable estimate, and each one after it is less certain. Cycles vary by a few days, and the error adds up across several months.
Sources and evidence
Free Calculators Online is independent and is not affiliated with or endorsed by the source organizations. Educational estimates only.