The cholesterol ratio divides total cholesterol by HDL — the protective "good" cholesterol — into a single heart-health screening number. A lower ratio is better. This tool also reports non-HDL cholesterol (total − HDL), which captures the harmful particles.
Reviewed: June 20, 2026 · Author: Naveen P N, Founder — AI Calculator · Verified against: standard lipid-ratio bands, recomputed in code.
The formulas
The ratio is unitless, so it gives the same answer whether your lab reports in mg/dL (United States) or mmol/L (most other countries) — only both inputs must share the same unit. Because HDL sits in the denominator, raising HDL lowers the ratio, which is why exercise and a heart-healthy diet help. Non-HDL cholesterol is increasingly used alongside the ratio because it sums up every harmful particle in one figure.
Worked examples (mg/dL)
Total 200, HDL 50:
Total 240, HDL 40:
Total 180, HDL 60:
A very low HDL pushes the ratio up sharply: total 200 with HDL 25 gives a ratio of 8.0 — high risk — even though total cholesterol looks moderate. That is why HDL matters as much as the total number.
Frequently Asked Questions
<3.5 optimal, 3.5–5 desirable, 5–7 increased, ≥7 high. Aim under 5, ideally near 3.5.
Total cholesterol ÷ HDL. 200 ÷ 50 = 4.0. Unitless — mg/dL or mmol/L both work.
Total minus HDL — all the harmful cholesterol. For 200/50 it's 150. Lower is better.
Both summarize risk usefully; clinicians weigh them with age, BP, smoking and diabetes.
No — an educational screening tool. A clinician should interpret your full lipid panel.