Cholesterol Ratio Calculator
Enter your lipid panel to find the three cholesterol ratios doctors watch most, total-to-HDL, LDL-to-HDL and triglyceride-to-HDL, plus your non-HDL cholesterol. Leave LDL blank and we will estimate it for you with the Friedewald equation. Each result is matched to its heart-risk band.
Formula
Worked example
With total 200, HDL 50, triglycerides 150 mg/dL: total/HDL = 200 / 50 = 4.0:1 (acceptable). Friedewald LDL = 200 - 50 - 150/5 = 120 mg/dL, so LDL/HDL = 120 / 50 = 2.4:1. TG/HDL = 150 / 50 = 3.0:1. Non-HDL = 200 - 50 = 150 mg/dL.
What the cholesterol ratios tell you
The total cholesterol to HDL ratio divides your total cholesterol by your HDL ("good") cholesterol. Because HDL helps clear cholesterol from your arteries, a higher HDL relative to total cholesterol produces a lower, more favourable ratio. The American Heart Association suggests aiming for a ratio below 5, with around 3.5 considered optimal. This calculator also reports two other ratios clinicians watch. The LDL/HDL ratio weighs "bad" against "good" cholesterol directly, with below 2.0 considered ideal. The triglyceride/HDL ratio is a simple stand-in for insulin resistance and small, dense LDL particles, and you read it against a different band depending on whether your lab uses mg/dL or mmol/L.
How LDL is estimated when you leave it blank
If your panel does not report LDL directly, leave the LDL field at zero and the calculator estimates it with the Friedewald equation: LDL equals total cholesterol minus HDL minus triglycerides divided by five (in mg/dL), or divided by 2.2 in mmol/L. That divisor approximates the cholesterol carried in VLDL particles. The Friedewald estimate is reliable when triglycerides are below 400 mg/dL (4.5 mmol/L) and the sample is fasting. Above that level the equation systematically underestimates LDL, which is why clinical laboratories stop reporting a calculated LDL there, and why this calculator leaves the LDL and LDL/HDL fields blank instead. Whenever you type an LDL value, the calculator uses your number and skips the estimate.
Why non-HDL cholesterol matters too
Non-HDL cholesterol is simply your total cholesterol minus your HDL. It bundles together LDL ("bad") cholesterol and other atherogenic particles such as VLDL remnants, all of which can deposit cholesterol in artery walls. Many guidelines now treat non-HDL as a better predictor of cardiovascular events than LDL alone, partly because it needs no fasting and no special calculation. A lower non-HDL figure means fewer harmful particles in circulation, so it complements the three ratios when you assess heart risk.
How to improve all of these numbers
The ratios improve when total and LDL cholesterol or triglycerides fall, or when HDL rises, and lifestyle moves all of them at once. Regular aerobic exercise, replacing saturated and trans fats with unsaturated fats, cutting refined carbohydrates and alcohol to lower triglycerides, eating more soluble fibre, losing excess weight and not smoking all tend to help. When lifestyle changes are not enough, doctors may prescribe statins or other medicines. Track your numbers over time rather than reacting to a single reading, and interpret them alongside blood pressure and your overall risk profile.
Cholesterol ratio target bands
| Ratio | Ideal | Borderline | High risk |
|---|---|---|---|
| Total / HDL | Below 3.5 | 3.5 to 5.0 | Above 5.0 |
| LDL / HDL | Below 2.0 | 2.0 to 5.0 | Above 5.0 |
| TG / HDL (mg/dL) | Below 2.0 | 2.0 to 6.0 | Above 6.0 |
| TG / HDL (mmol/L) | Below 0.87 | 0.87 to 2.62 | Above 2.62 |
Lower is better for all three ratios. Total/HDL and LDL/HDL are unitless, so they read the same in mg/dL or mmol/L. The triglyceride/HDL band differs by unit because both values change. The total/HDL bands follow the Framingham Heart Study risk gradient that the American Heart Association cites (about 3.5 optimal, above 5 higher risk); the LDL/HDL and triglyceride/HDL bands are widely used laboratory conventions rather than figures set by a guideline body, so read them as context, not targets. The NIH goal for non-HDL cholesterol is below 130 mg/dL in adults.
Frequently asked questions
What is a good cholesterol ratio?
For the total-to-HDL ratio, below 5 is the usual ceiling and around 3.5 is often described as optimal; that gradient comes from the Framingham Heart Study data the American Heart Association cites. The LDL/HDL band (below 2.0 ideal, above 5.0 high) and the triglyceride/HDL band (below 2.0 in mg/dL, below 0.87 in mmol/L) are laboratory conventions rather than numbers set by a guideline body, so treat them as context. Lower is better for all three.
How do you estimate LDL if it is not on my panel?
This calculator uses the Friedewald equation: LDL equals total cholesterol minus HDL minus triglycerides divided by five (mg/dL) or 2.2 (mmol/L). Leave the LDL field blank (zero) and enter your triglycerides to use it. The equation is only valid for fasting samples with triglycerides up to 400 mg/dL (4.5 mmol/L), so above that level the calculator withholds the estimate instead of reporting a figure that would run too low. Ask for a directly measured LDL and enter it.
Are the ratios the same in mg/dL and mmol/L?
The total/HDL and LDL/HDL ratios are unitless, so they are identical whether your lab reports in mg/dL or mmol/L. The triglyceride/HDL ratio is different because triglycerides and HDL convert by different factors, so it is read against a separate band for each unit. Non-HDL cholesterol is a concentration and is reported in whichever unit you entered.
Does this replace a doctor’s assessment?
No. These figures are general guidance, not a diagnosis. True cardiovascular risk also depends on LDL particle number, blood pressure, age, smoking, diabetes and family history. Discuss your full lipid panel with a healthcare professional.
Sources
- American Heart Association, What your cholesterol levels mean
- NIH MedlinePlus, Cholesterol levels: What you need to know (non-HDL goal below 130 mg/dL)
- NHLBI, Third Report of the National Cholesterol Education Program (ATP III) executive summary, which sets the 400 mg/dL triglyceride ceiling for the Friedewald estimate
- Friedewald WT, Levy RI, Fredrickson DS (1972). Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge. Clinical Chemistry 18(6):499-502.