Cholesterol Ratio Calculator

Total cholesterol to HDL ratio: below 3.5 is excellent, 3.5–5 is good, above 5 raises cardiovascular risk. LDL to HDL ratio: below 2 is excellent, 2–3 is good, above 3.5 is risky. The ratios matter because raw cholesterol numbers can mislead — high total cholesterol with high HDL is less risky than the same total with low HDL. So a person with total 220 mg/dL and HDL 70 has a ratio of 3.1 (good); the same total with HDL 35 gives 6.3 (high risk). Ratios capture the protective effect of HDL alongside the absolute lipid levels.

Total cholesterol to HDL ratio = total cholesterol ÷ HDL. Both in mg/dL or mmol/L (use same units). Example: total 200 mg/dL, HDL 50 mg/dL. Ratio = 200/50 = 4.0. This is a 'good' ratio. Below 3.5 is excellent, 3.5–5 is acceptable, above 5 raises cardiovascular risk. The ratio is valuable because it captures both elevated cholesterol and inadequate HDL in one number. A high total with high HDL is less risky than a moderately elevated total with low HDL — the ratio reflects this. Most lipid panel reports calculate this automatically.

Both have utility, but LDL to HDL ratio better focuses on the actual atherogenic vs protective lipoprotein balance. Total cholesterol includes HDL itself, which can muddy the picture. LDL/HDL: below 2 excellent, 2–3 good, above 3.5 risky. Total/HDL is more commonly reported because it requires fewer measurements. Modern guidelines emphasise non-HDL cholesterol (total minus HDL) and ApoB as even better predictors. For most patients, all three give similar guidance. The Castelli ratio (total/HDL) is the historical standard. LDL/HDL is more granular. Use whatever your lab and doctor focus on.

Non-HDL cholesterol = total cholesterol − HDL. It captures all the 'bad' cholesterol carriers — LDL, VLDL, IDL, lipoprotein(a) — in a single number. Target: below 130 mg/dL for general cardiovascular health, below 100 for high risk, below 80 for very high risk. Non-HDL is increasingly preferred over LDL alone because it includes other atherogenic lipoproteins that contribute to plaque buildup. It also doesn't require fasting and is calculated from the standard lipid panel. Many guidelines now recommend non-HDL alongside LDL as a primary treatment target.

Yes. A normal total cholesterol with low HDL gives a high ratio. Example: total 180 mg/dL (well within normal), HDL 30 mg/dL — ratio = 6.0, which is high cardiovascular risk despite normal-looking total. This is why ratios matter more than absolute totals. People with normal totals but low HDL — common in metabolic syndrome, sedentary lifestyle, or genetic patterns — are at increased risk and often missed by simple cholesterol screening. Always look at HDL, LDL, triglycerides, and the ratios together. Treatment focuses on raising HDL through exercise and weight loss, plus lowering LDL if needed.

Modern lipid panels often don't require fasting. Total cholesterol, HDL, and non-HDL cholesterol values are stable whether fasting or fed. Triglycerides do rise after meals, so a fasting test gives more accurate triglyceride values — and LDL calculated from the Friedewald equation requires accurate triglycerides. If you have very high triglycerides or are starting treatment, fasting (8–12 hours) gives cleaner numbers. For routine screening, modern guidelines from the European Society of Cardiology and many others accept non-fasting samples. Check with your lab — they'll specify if fasting is needed for your particular tests.