Cholesterol Calculator: LDL, Non-HDL & Ratio
From your total cholesterol, HDL, and triglycerides, calculate your LDL (Friedewald formula), your non-HDL cholesterol, and the TC/HDL ratio.
Non-HDL cholesterol (= total − HDL) captures all the “bad” cholesterol and stays valid even when triglycerides are high. Your LDL targets depend on your overall cardiovascular risk and are set by your clinician.
Understand the lipid panel (LDL, HDL, triglycerides)The Friedewald formula
On most lab reports, LDL cholesterol is not measured directly: it is calculated with the Friedewald formula1:
LDL = Total cholesterol − HDL − Triglycerides / 5
(the divisor is 5 in mg/dL, and 2.2 in mmol/L). This estimate becomes unreliable above about 400 mg/dL of triglycerides: LDL should then be measured directly.
Why non-HDL cholesterol?
Non-HDL cholesterol (total cholesterol − HDL) captures all the “atherogenic” fractions. It is emphasized by U.S. cholesterol guidelines2 because it stays reliable even with high triglycerides and does not depend on fasting.
How to read the result
Your LDL and non-HDL targets depend on your overall cardiovascular risk (age, blood pressure, smoking, diabetes, history…) and are set by your clinician: there is no single threshold that fits everyone. This calculation helps you understand your numbers, not to place yourself on your own. To convert your values between mg/dL and mmol/L, use our unit converter.
Frequently asked questions
How is LDL cholesterol calculated?
Most often with the Friedewald formula: LDL = total cholesterol − HDL − triglycerides/5 (in mg/dL), or /2.2 in mmol/L. LDL is therefore usually calculated, not measured directly.
Why can’t my LDL be calculated?
The Friedewald formula becomes unreliable when triglycerides exceed about 400 mg/dL (4.5 mmol/L). In that case, LDL should be measured directly in the lab. Non-HDL cholesterol, however, stays usable.
What is non-HDL cholesterol?
It is total cholesterol minus HDL: it captures all the “atherogenic” fractions (LDL and others). It is increasingly used because it stays reliable even with high triglycerides and does not require fasting.
What is a good total cholesterol / HDL ratio?
A lower ratio is generally more favorable. But no single value stands alone: the target depends on your overall cardiovascular risk, assessed by your clinician.
Do I need to fast?
A 12-hour fast was classically recommended for a lipid panel, especially for triglycerides. Many guidelines now accept a non-fasting panel for routine screening; follow your lab’s instructions.
Disclaimer. This tool provides a calculation for information only. It does not diagnose anything and does not replace the advice of a healthcare professional. Interpreting a lipid panel depends on your overall cardiovascular risk and belongs to your clinician.
Sources
- 1
Friedewald WT, Levy RI, Fredrickson DS. — “Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge.” Clin Chem, 1972. · PubMed
- 2
Grundy SM, et al. (AHA/ACC) — “2018 AHA/ACC/Multisociety Guideline on the Management of Blood Cholesterol.” Circulation, 2019. · PubMed · DOI