Cholesterol to HDL ratio calculator
Your total cholesterol divided by your HDL ("good") cholesterol. Some labs print it as a single number that sums up your cholesterol balance. Type your results in the units on your report and it works out Chol/HDL Ratio as you type, in your browser.
AI-verified against cited sources. Awaiting expert reviewLast reviewed 2026-10-03Heart & Cholesterol
Type your results above, or fill in the example, to see Chol/HDL Ratio.
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Educational information, not medical advice. Blood Test Tracker doesn’t diagnose or treat, and it doesn’t replace your clinician. Talk with your clinician before changing medications, supplements or care.
How it’s worked out
The formula
Total cholesterol / HDL-C, with both values in the same unit (for example mg/dL). The unit cancels, so the ratio is the same number in mg/dL and mmol/L.
A worked example
Example numbers, not anyone’s real results, run through the same code as the calculator above.
| Total Cholesterol | 200 mg/dL |
|---|---|
| HDL | 50 mg/dL |
| Chol/HDL Ratio | 4.0 ratio |
For an adult, this result is in the usual range.
What Chol/HDL Ratio tells you
This ratio is simple division: total cholesterol divided by HDL cholesterol, with both numbers in the same unit. A ratio of 4 means your total cholesterol is four times your HDL. It is also called the Castelli Risk Index I. Your lab works it out for you, and it has no unit. A lower ratio means less of your cholesterol sits outside the protective HDL particles.
A ratio can show something that total cholesterol alone hides. A higher total cholesterol can come mostly from protective HDL, while a normal total with low HDL gives a higher ratio. Clinicians have used the ratio for many years as a quick signpost for heart risk. Newer guidelines focus on LDL and non-HDL cholesterol instead, and Mayo Clinic notes that non-HDL may be more useful than the ratio. So the ratio works best as a supporting number.
Read the full page on Chol/HDL Ratio, with what a high or low result can mean.
Usual ranges
The ranges the result above is placed on. Your own lab’s printed range comes first if it gives one.
Sources
The equation
- Lipid Panel with Ratios, Quest Diagnostics (reference ranges as listed by Fullscript), Quest Diagnostics (via Fullscript)
- Lipid Panel With Total Cholesterol:HDL Ratio (test 221010), Labcorp
- Cholesterol ratio or non-HDL cholesterol: Which is most important? (read from a 2025 Internet Archive copy), Mayo Clinic
6 more sources for the ranges and the explanation
- Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III): Executive Summary, NHLBI / National Institutes of Health (2001)
- Understanding the new dyslipidemia guidelines, Quest Diagnostics (2026)
- Fasting is not routinely required for determination of a lipid profile: clinical and laboratory implications including flagging at desirable concentration cutpoints. A joint consensus statement from the European Atherosclerosis Society and European Federation of Clinical Chemistry and Laboratory Medicine, European Heart Journal (joint EAS/EFLM statement, also in Clinical Chemistry) (2016)
- Dyslipidemia (Hyperlipidemia), Merck Manual Professional Edition
- Lipid Profile Testing and Interpretation (summarizes the 2026 ACC/AHA Dyslipidemia Guideline), Circulation (Nguyen, Ahmad, Navar) (2026)
- 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Blood Cholesterol: Executive Summary, ACC/AHA Task Force on Clinical Practice Guidelines (2019)
AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. The calculator is version 1.0.0 of our code for this equation, tested against published examples. How we build and check these pages.