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Cholesterol ratio and LDL calculator

Enter your lipid results to calculate LDL, non-HDL and cholesterol ratios. Use the units on your report.

Educational estimate. Qualified clinical review has not been performed. Do not use this result to diagnose a condition or choose treatment.

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Calculator measurements

Sampson/NIH LDL estimate, non-HDL, total/HDL, LDL/HDL and both TG/HDL ratios. Values are not personal treatment targets.

Total cholesterol from the same lipid panel.

HDL-C from the same lipid panel.

Use the value from the same blood sample as the other results.

Your result will appear here

Enter your measurements above, or try the worked example. Entry limits are not healthy reference ranges.

Inputs and results stay in this page's memory. They are not saved, uploaded or added to links. Changing units clears that value.

Conceptual illustration of larger and smaller lipoprotein particles beside an orange comparison curve.

What this result means

Total/HDL is total cholesterol divided by HDL. Non-HDL is total cholesterol minus HDL. Estimated LDL needs triglycerides too. This tool uses the Sampson/NIH equation as its main LDL estimate, with Friedewald shown only as a suitable comparison. Ratios are not your full cardiovascular risk. [1][2]

What you get

LDL estimated with Sampson/NIH in mmol/L and mg/dL, total/HDL, estimated LDL/HDL, non-HDL in both units and TG/HDL in both labelled conventions. A Friedewald comparison appears only when its triglyceride range and result are suitable. Ratios-only mode needs total and HDL cholesterol.

Why this calculator sometimes withholds LDL

Friedewald is not reported at TG 400 mg/dL or above. This tool also stops Sampson LDL at TG 800 mg/dL or above. Negative estimates and estimates above non-HDL are withheld rather than set to zero. Valid arithmetic ratios and non-HDL remain available, with a clear explanation. [1][2]

Put cholesterol in its wider context

Your personal plan depends on cardiovascular history, diabetes, kidney disease, smoking, blood pressure and other factors. The 2026 guideline prefers Martin/Hopkins or Sampson/NIH estimation over Friedewald. A favourable ratio does not replace consideration of LDL, non-HDL and relevant additional tests. [2]

What is a good cholesterol ratio?

There is no ratio that makes the rest of a lipid panel irrelevant. Ratios describe the relationship between measurements; treatment goals depend on the person's overall clinical risk. This calculator does not assign a universal green band or tell you that high LDL is safe. [2]

Is calculated LDL as accurate as measured LDL?

It depends on the lipid pattern, assay and estimation equation. Sampson improves estimation in some situations compared with Friedewald, but it is still an estimate. A laboratory may use another validated method. Ask which method was used if numbers differ. [1]

What is non-HDL cholesterol?

It is total cholesterol minus HDL cholesterol, so it includes cholesterol carried by multiple non-HDL particles. It needs no triglyceride-based LDL estimate. For total 200 mg/dL and HDL 50 mg/dL, non-HDL is 150 mg/dL. [2]

Do I need to fast for a cholesterol ratio?

The arithmetic itself does not require fasting. Sampling context matters for interpretation and triglycerides; a clinician may request a repeat fasting panel for certain results. Use measurements from one sample and follow the instructions for your own test. [2]

Do cholesterol ratios change between mg/dL and mmol/L?

Total/HDL and LDL/HDL do not change when both cholesterol measurements use the matching conversion factor. TG/HDL does change because triglycerides and cholesterol use different factors. This tool shows both TG/HDL conventions explicitly.

Does this calculate my 10-year heart risk?

No. A validated cardiovascular risk model needs additional information and population-specific clinical interpretation. LDL and ratios alone cannot give that risk. Do not interpret a calculator result as a reason to stop prescribed lipid treatment.

Formula and assumptions

Formula
Sampson LDL (mg/dL) = TC/0.948 − HDL/0.971 − [TG/8.56 + TG×(TC−HDL)/2140 − TG²/16100] − 9.44. Friedewald = TC − HDL − TG/5. Non-HDL = TC − HDL. Ratios use the stated unit basis. [1][2]
Version
Sampson/NIH LDL; Friedewald comparison; lipid ratios, sampson-nih-2020.boundary-800.friedewald-400.v1
Rounding
Calculate internally in mg/dL; convert the final estimate to mmol/L. Display mmol/L and ratios to two decimals and mg/dL to one decimal.
Worked example
With total cholesterol 200 mg/dL, HDL 50 mg/dL and triglycerides 100 mg/dL, Sampson estimates LDL 131.97 mg/dL before display rounding (3.41 mmol/L). Friedewald gives 130 mg/dL, total/HDL is 4.00 and non-HDL is 150 mg/dL. These are example measurements, not targets. [1]

Who this is for — and when not to use it

Intended use

Educational lipid arithmetic and a transparent LDL estimate from a comparable adult lipid panel.

Not intended for

Medication dosing, treatment targets, familial hypercholesterolaemia diagnosis or a 10-year cardiovascular risk estimate.

Exclusions

  • HDL above total cholesterol, negative values or mismatched sampling dates.
  • Sampson LDL at triglycerides ≥800 mg/dL; Friedewald at ≥400 mg/dL.
  • Negative estimated LDL or estimated LDL above non-HDL.
  • Using a favourable ratio to dismiss high LDL, non-HDL or ApoB.

Evidence sources

  1. 1. A new equation for calculation of low-density lipoprotein cholesterol — Sampson et al., JAMA Cardiology. Accessed Oct 4, 2026.
  2. 2. 2026 guideline on the management of dyslipidemia — ACC/AHA and partner organisations. Accessed Oct 4, 2026.