Cholesterol Ratio Calculator
Work out your total-cholesterol-to-HDL ratio and non-HDL cholesterol from a lipid panel, in mmol/L or mg/dL.
Your total-to-HDL ratio, the figure heart-risk tools use.
How the cholesterol ratio calculator works
Cardiovascular risk tools rarely use total cholesterol on its own; they use the ratio of total cholesterol to HDL ("good") cholesterol, because a high total is less worrying when much of it is HDL. Divide total by HDL and you have the ratio — the units cancel, so it is the same in mmol/L and mg/dL. Non-HDL cholesterol (total minus HDL) is the other figure guidelines increasingly quote, since it captures all the particles that deposit in arteries.
The verdict uses the common bands: under 3.5 is often described as ideal, up to 5 acceptable, above 5 raized. Risk depends on age, blood pressure, smoking and more — the ratio is one input to a risk calculator, not a diagnosis.
Formula: ratio = total ÷ HDL · non-HDL = total − HDL
Worked examples
| Inputs | Total ÷ HDL ratio | Note |
|---|---|---|
| 5.5 total, 1.3 HDL (mmol/L) | 4.23 | ratio 4.2 |
| 210 total, 50 HDL (mg/dL) | 4.2 | ratio 4.2 — units cancel |
| 4.6 total, 1.6 HDL (mmol/L) | 2.87 | under 3.5 |
| 6.8 total, 1.0 HDL (mmol/L) | 6.8 | a raized ratio |
FAQFrequently asked questions
Why a ratio rather than total cholesterol?
Because HDL carries cholesterol away from arteries. Two people with a total of 6 differ a lot if one has HDL of 2 and the other 1 — ratios of 3 and 6. Risk tools use the ratio for that reason.
What is non-HDL cholesterol?
Total minus HDL: LDL plus the other particles that deposit in artery walls. Many guidelines now treat it as the primary target because it does not need a fasting sample.
How do I convert mmol/L to mg/dL?
Multiply by 38.67 for cholesterol (divide to go back). The ratio needs no conversion.
Is a ratio under 3.5 a clean bill of health?
It is a favorable lipid picture, not a verdict on heart risk, which also depends on age, sex, blood pressure, smoking, diabetes and family history. Risk calculators combine all of those.
Where these figures come from
- Mifflin MD et al., "A new predictive equation for resting energy expenditure in healthy individuals", Am J Clin Nutr 1990 — the BMR equation used here
- World Health Organization — Waist circumference and waist–hip ratio (2008 expert consultation) — waist-to-hip cut-offs
- Tanaka H, Monahan KD, Seals DR, "Age-predicted maximal heart rate revisited", J Am Coll Cardiol 2001 — 208 − 0.7 × age
- Nathan DM et al., "Translating the A1C assay into estimated average glucose values" (ADAG), Diabetes Care 2008 — eAG = 28.7 × A1c − 46.7
- Mosteller RD, "Simplified calculation of body-surface area", N Engl J Med 1987 — BSA = √(height × weight / 3600)
- Centers for Disease Control and Prevention — national health guidance
Last checked: September 2026. The equations are fixed by their published papers and do not change with tax years or regulations; the thresholds quoted in verdicts name the body that set them.