Cholesterol Ratio Calculator
Work out your total-cholesterol-to-HDL ratio, LDL-to-HDL ratio and non-HDL cholesterol from a standard lipid panel. Enter your values in mg/dL or mmol/L; if you leave LDL blank it is estimated with the Friedewald equation. A reference tool, not medical advice.
How the ratios are calculated
The total-cholesterol-to-HDL ratio is TC ÷ HDL, and the LDL-to-HDL ratio is LDL ÷ HDL. Both are unitless, so they read the same in mg/dL or mmol/L. Non-HDL cholesterol is total cholesterol minus HDL and is reported in your chosen unit. When you leave LDL blank, it is estimated with the Friedewald equation from total cholesterol, HDL and triglycerides.
Frequently asked questions
How do you calculate the cholesterol ratio?
The cholesterol ratio is total cholesterol divided by HDL cholesterol (TC ÷ HDL). For example, a total cholesterol of 200 and an HDL of 50 give a ratio of 4.0. Because it is a ratio of two values in the same units, the number is identical whether you measure in mg/dL or mmol/L.
What is a good cholesterol ratio?
A lower cholesterol ratio is generally better. A TC/HDL ratio below about 3.5 is often described as optimal, up to about 5 as average, and above 5 as less favourable. These are broad guides — your personal target depends on your overall cardiovascular risk, and no single ratio replaces a clinical assessment.
What is non-HDL cholesterol?
Non-HDL cholesterol is total cholesterol minus HDL (TC − HDL). It captures all the cholesterol carried by potentially atherogenic particles (LDL, VLDL and others) in one number, and many guidelines now treat it as a primary target because it does not require fasting or an LDL estimate. Unlike the two ratios it is an absolute concentration, so this calculator reports it in whichever unit you have selected — a total of 200 mg/dL with an HDL of 50 mg/dL gives a non-HDL of 150 mg/dL. It can be read off any lipid panel, since it needs neither a triglyceride value nor a direct LDL measurement.
How is LDL estimated when I leave it blank?
The calculator uses the Friedewald equation: LDL = total cholesterol − HDL − triglycerides ÷ 5 (in mg/dL), or triglycerides ÷ 2.2 (in mmol/L). It needs a triglyceride value and becomes unreliable when triglycerides are high (above about 400 mg/dL or 4.5 mmol/L) or when a direct LDL is available — enter your measured LDL if you have it. With the values this page starts on — total 200, HDL 50 and triglycerides 150 mg/dL — Friedewald returns an LDL of 120 mg/dL. The result card labels that figure “Estimated (Friedewald)”, and warns instead that the triglycerides are too high to be reliable once they pass 400 mg/dL (4.5 mmol/L).
Is the ratio the same in mg/dL and mmol/L?
Both ratios are unit-free, so TC/HDL and LDL/HDL read the same number in mg/dL and in mmol/L — dividing two values in the same units cancels the units out. Non-HDL cholesterol, however, is an absolute value, so it is reported in whichever unit you selected. Switching the unit toggle converts the entered figures too (cholesterol by 38.67, triglycerides by 88.57), which is why the ratios hold steady while the non-HDL number changes. A TC/HDL of 4.0 therefore means exactly the same thing on a US and a European lipid report.
This is a reference tool, not a diagnosis or medical advice. Results depend on the laboratory, assay and clinical context, and reference intervals vary between labs and by age and sex — always read your result against the range printed on your own report and discuss it with a qualified healthcare professional.
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