LDL Cholesterol Calculator

Estimate your LDL ("bad") cholesterol from a standard lipid panel. Uses the Friedewald equation, with a toggle for the Sampson (NIH) equation that stays accurate at higher triglycerides.

LDL cholesterol is usually calculated, not measured: LDL = total cholesterol − HDL − (triglycerides ÷ 5) in mg/dL (the Friedewald equation). Under 100 mg/dL (2.6 mmol/L) is optimal for low-risk adults; high-risk patients are advised to aim lower.

Friedewald & Sampson (NIH) equations mg/dL and mmol/L Medically reviewed
Units
Enter your total cholesterol, HDL and triglycerides to estimate LDL. Everything is computed locally in your browser — no data leaves this page.

Does your LDL reading vary for you?

The calculation is the same for everyone — but the equation you should use, and the target you're aiming for, do change. Here's where.

Equation choiceChanges the math
Friedewald uses a fixed triglyceride divisor of 5 and breaks down above 400 mg/dL. Sampson (NIH) is a closed-form equation validated up to 800 mg/dL and is more accurate when triglycerides are raised. The calculator picks the right one for you — Friedewald normally, Sampson automatically when your triglycerides are high — and you can switch methods under the result.
Age & sexChanges the target
Neither changes how LDL is calculated. They change your target, because cardiovascular risk rises with age and varies by personal and family history. A higher-risk person is advised to aim for a lower LDL than a low-risk person with the identical number.
Region / guidelineChanges the target
Targets differ by guideline. US ACC/AHA targets under 70 mg/dL for high-risk patients; European ESC/EAS targets under 55 mg/dL (1.4 mmol/L) for very-high-risk; UK NICE emphasises non-HDL reduction over a fixed LDL number. Same LDL, different goal depending on where you are.

How LDL cholesterol is calculated

LDL is usually estimated from the other values on your lipid panel rather than measured directly. Here are the exact equations behind the calculator.

Friedewald equation (mg/dL)
LDL = Total cholesterol − HDL − (Triglycerides ÷ 5)
In mmol/L the divisor is 2.2. Not valid when triglycerides exceed 400 mg/dL (≈4.5 mmol/L).
Sampson (NIH) equation (mg/dL)
LDL = TC/0.948 − HDL/0.971 − (TG/8.56 + TG×nonHDL/2140 − TG²/16100) − 9.44
nonHDL = TC − HDL. Validated for triglycerides up to 800 mg/dL.

The Friedewald equation estimates VLDL cholesterol as triglycerides divided by 5, then subtracts it along with HDL from total cholesterol. It's simple and has been the standard for decades, but the fixed divisor of 5 is what makes it inaccurate when triglycerides are high — which is why it's not used above 400 mg/dL.

Two equations improve on it. The Martin-Hopkins equation replaces the fixed divisor with an adjustable factor selected from a validated 180-cell table based on your triglyceride and non-HDL levels — more accurate at high triglycerides, but it depends on that lookup table rather than a single formula, so this calculator doesn't reproduce it (a transcription slip in that table would be a wrong clinical number). The Sampson (NIH) equation, which the calculator switches to automatically when your triglycerides are high, is a closed-form formula validated to 800 mg/dL — accurate at high triglycerides while remaining a single equation you can reproduce and check.

What your LDL result means

These are the long-standing NCEP/ATP III reference categories for LDL. They're a general guide — your personal target depends on your cardiovascular risk and is set by your clinician (see the guideline table note below).

CategoryLDL (mg/dL)LDL (mmol/L)
OptimalBelow 100Below 2.6
Near optimal100–1292.6–3.3
Borderline high130–1593.4–4.1
High160–1894.1–4.9
Very high190 or above4.9 or above
Your target may be lower than "optimal"
These categories describe the population reference. If you have established cardiovascular disease, diabetes, or high overall risk, guidelines set a personal target well below 100 — the US ACC/AHA at under 70 mg/dL and the European ESC/EAS at under 55 mg/dL (1.4 mmol/L) for the highest-risk patients. Read your LDL against the target your clinician sets, not the generic category alone.

Frequently asked questions

How do you calculate LDL cholesterol?
LDL is usually estimated rather than measured directly. The Friedewald equation is LDL = total cholesterol − HDL − (triglycerides ÷ 5) when values are in mg/dL (the divisor is 2.2 for mmol/L). Enter your total cholesterol, HDL and triglycerides into the calculator above and it applies the equation. When triglycerides exceed 400 mg/dL, the Friedewald estimate becomes unreliable and the Sampson equation or a direct LDL measurement should be used.
What is the new calculation for LDL cholesterol?
Two newer equations improve on Friedewald at higher triglycerides. Martin-Hopkins replaces the fixed triglyceride divisor of 5 with an adjustable factor from a validated table. Sampson (NIH), published in 2020, is a closed-form formula validated for triglycerides up to 800 mg/dL. This calculator computes Friedewald and Sampson; both are exact formulas you can reproduce and check.
What should my LDL cholesterol be?
There's no single number — your target depends on your overall cardiovascular risk and which guideline applies. As a general reference, LDL under 100 mg/dL (2.6 mmol/L) is optimal for low-risk adults. High-risk patients are advised to aim lower: US ACC/AHA targets under 70 mg/dL for high-risk patients, and European ESC/EAS targets under 55 mg/dL (1.4 mmol/L) for very-high-risk patients. Your clinician sets your personal target from your full risk profile.
Does the LDL target differ by age, sex or country?
The way LDL is calculated doesn't change with age, sex or country — the equation is the same for everyone. What changes is the target. Targets are driven by cardiovascular risk, which rises with age and differs by personal history, and by which guideline your clinician follows: US ACC/AHA, European ESC/EAS, and UK NICE set different thresholds and emphasise different measures (NICE focuses on non-HDL cholesterol reduction rather than a fixed LDL target).
Why is my calculated LDL different from my lab's direct LDL?
Calculated LDL is estimated from your other lipid values, while a direct LDL test measures it in the lab. The two can differ, especially when triglycerides are high or you weren't fasting, because the equations assume a fixed relationship between triglycerides and VLDL cholesterol that doesn't always hold. Above 400 mg/dL of triglycerides, calculated LDL is unreliable and a direct measurement is preferred.

References & Guidelines

Note: This calculator is for informational purposes and does not replace medical advice. Calculated LDL is an estimate and is less reliable at high triglyceride levels or in a non-fasting sample. Interpret your result against the target your clinician sets and the reference range printed on your own report.

LDL is just one marker

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