Cholesterol Calculator
Use this cholesterol calculator to find your LDL cholesterol and total-to-HDL ratio from a standard lipid panel.
Updated October 22, 2026
Medical Disclaimer: This calculator gives a general estimate for education only and cannot diagnose a condition. Share your result with your doctor or the clinician who ordered your test, and do not start, stop or change any medicine based on it. Read our full Medical Disclaimer.
How LDL Cholesterol Is Calculated
Most routine lipid panels measure total cholesterol, HDL, and triglycerides directly, but not LDL itself, LDL is usually calculated from the other three rather than measured separately, since direct LDL measurement is more expensive and not always necessary¹.
What This Calculator Measures
This calculates LDL cholesterol from your total cholesterol, HDL, and triglycerides, plus the total-to-HDL ratio, a commonly cited secondary way a lipid panel gets interpreted.
The Formula
LDL = Total Cholesterol − HDL − (Triglycerides ÷ 5), in mg/dL
This is the Friedewald formula, developed in 1972. The calculator shows it for comparison, and its main result uses the Sampson/NIH equation shown below. It's invalid above roughly 400 mg/dL triglycerides and becomes progressively less accurate at high triglycerides or low LDL even below that threshold¹.
Cholesterol ratio = Total Cholesterol ÷ HDL
How This Calculator Computes Your Result
Enter your total cholesterol, HDL, and triglycerides. Up to 800 mg/dL triglycerides, we calculate LDL with the Sampson/NIH equation shown below, one of the two methods the 2026 US cholesterol guideline prefers over Friedewald³ ⁶. Below 400 mg/dL, we also show the Friedewald result for comparison, because some lab reports still use it. Above 800 mg/dL, even Sampson's own validation doesn't extend that far, so we flag the result rather than show a number neither formula can support. The cholesterol ratio is calculated directly regardless of triglyceride level.
Why Friedewald Isn't the Only Option Anymore
Friedewald's fixed ÷5 divisor was a reasonable approximation in 1972, but it doesn't hold up well across the full range of real-world triglyceride and LDL levels. The Martin/Hopkins method replaced that fixed divisor with one that varies based on the person's own triglyceride and non-HDL cholesterol levels, and was shown to outperform Friedewald, especially at high triglycerides or low LDL².
The 2026 US cholesterol guideline now prefers either Martin/Hopkins or the Sampson/NIH equation over Friedewald, especially when triglycerides are 150 mg/dL or higher or LDL is below 70 mg/dL⁶. This calculator uses the Sampson/NIH equation, a single formula that did as well as Martin/Hopkins below 400 mg/dL triglycerides and stays accurate up to 800 mg/dL³.
Sampson LDL = TC ÷ 0.948 − HDL ÷ 0.971 − (TG ÷ 8.56 + (TG × non-HDL) ÷ 2140 − TG² ÷ 16100) − 9.44, in mg/dL
Cholesterol Levels Chart
Standard US categories for each part of a lipid panel, for adults and for children and teens. Enter a result to mark it.
- Desirable or acceptable
- Borderline
- High
Show data table
| Group | Desirable or acceptable | Near optimal | Borderline | High | Very high | Low (HDL) | High (HDL) |
|---|---|---|---|---|---|---|---|
| Adults (ATP III) | Desirable: below 200 | – | Borderline high: 200 to 239 | High: 240 and above | – | – | – |
| Children and teens | Acceptable: below 170 | – | Borderline high: 170 to 199 | High: 200 and above | – | – | – |
A Note on Accuracy
A calculated LDL is an estimate derived from other values, not a direct measurement. The 2026 US cholesterol guideline prefers the Sampson/NIH or Martin/Hopkins equations over most direct LDL tests, except the reference method (beta-quantification)⁶. The Sampson/NIH equation's own validation stops at 800 mg/dL triglycerides, above that level neither formula this calculator uses is reliable, and a direct LDL measurement is needed. Cholesterol values alone don't determine cardiovascular risk, they're one input among several used in real risk assessment. This uses the numbers on your lab report. It cannot diagnose a condition. Ask the clinician who ordered the test what your result means for you.
Frequently Asked Questions
What happens between 400 and 800 mg/dL triglycerides?
Up to 800 mg/dL, the calculator uses the Sampson/NIH equation³ ⁶. Below 400 mg/dL it also shows the older Friedewald result for comparison¹. Between 400 and 800 mg/dL, Friedewald cannot be used, so you get the Sampson/NIH result only, which stays accurate in that range³.
What happens if my triglycerides are extremely high?
At that point, even the Sampson/NIH equation is outside its own validated range³, so the calculator won't display a number from either formula. A direct LDL measurement is needed instead of any calculated estimate.
What is the total-to-HDL ratio?
Total Cholesterol ÷ HDL Cholesterol, a commonly cited secondary way a lipid panel gets interpreted alongside the individual values.
Does cholesterol alone determine my heart disease risk?
No. Cholesterol values are one input among several, including age, blood pressure, smoking status, diabetes, and family history, used in real cardiovascular risk assessment.
Sources
Estimation of the Concentration of Low-Density Lipoprotein Cholesterol in Plasma, Without Use of the Preparative Ultracentrifuge, Friedewald, Levy & Fredrickson, Clinical Chemistry, 1972
Comparison of a Novel Method vs the Friedewald Equation for Estimating Low-Density Lipoprotein Cholesterol Levels, Martin et al., JAMA, 2013
A New Equation for Calculation of Low-Density Lipoprotein Cholesterol in Patients With Normolipidemia and/or Hypertriglyceridemia, Sampson et al., JAMA Cardiology, 2020
2026 ACC/AHA Multisociety Guideline on the Management of Dyslipidemia, American College of Cardiology and American Heart Association, 2026