Cholesterol Ratio Calculator

Why ratios beat single-number cholesterol thresholds

The classic "total cholesterol < 200" target collapses a complex risk picture into a single number. Two people with TC=200 mg/dL can have radically different CVD risk profiles: one with HDL 80 and LDL 100 (TC/HDL = 2.5, low risk) vs another with HDL 30 and LDL 150 (TC/HDL = 6.7, high risk). The Framingham Heart Study and subsequent meta-analyses showed that ratios capture this nuance — and that LDL reduction relative to HDL is what drives event risk, not absolute levels. Modern cardiology guidelines emphasise non-HDL cholesterol and apoB particle counts for this reason.

The four ratios — what each tells you

TC/HDL ratio (total ÷ HDL): the classic Framingham predictor of coronary heart disease. Optimal <3.5, target <5.0, high >5.0. Captures the overall balance of atherogenic vs protective particles.

LDL/HDL ratio: more specific than TC/HDL because LDL is the primary atherogenic particle. Optimal <2.5, target <3.5, high >3.5. Less commonly cited than TC/HDL because the information overlaps substantially.

TG/HDL ratio: the strongest single marker for insulin resistance and atherogenic dyslipidemia. In mg/dL: optimal <2, target <3, insulin resistance threshold ≥3.5 (McLaughlin 2003). In mmol/L the cutoff converts to ~1.5. Rises with metabolic syndrome, poor glycemic control, and visceral obesity.

Non-HDL cholesterol (total − HDL): captures all apoB-containing atherogenic particles in one number. ACC/AHA 2018 targets: low risk <130 mg/dL, statin therapy consideration ≥160 mg/dL. Increasingly preferred over LDL as a treatment target because it includes VLDL remnants and Lp(a) that LDL alone misses.

What the targets actually are

• TC/HDL: optimal <3.5 · target <5.0 · high >5.0
• LDL/HDL: optimal <2.5 · target <3.5 · high >3.5
• TG/HDL (mg/dL): optimal <2 · target <3 · insulin resistance ≥3.5
• TG/HDL (mmol/L): optimal <0.87 · target <1.3 · insulin resistance ≥1.5
• Non-HDL: low risk <130 mg/dL · borderline 130–160 · high ≥160
• HDL alone: optimal >60 mg/dL (1.55 mmol/L) · low <40 men, <50 women
• Triglycerides alone: normal <150 mg/dL · borderline 150–199 · high 200–499 · very high ≥500

The TG/HDL ratio's special role in metabolic health

Insulin resistance produces a characteristic lipid triad: elevated triglycerides (because insulin\'s suppression of hepatic VLDL production is impaired), low HDL (because cholesterol ester transfer protein activity increases), and small dense LDL particles. TG/HDL ratio captures the first two with a single number and correlates strongly with both insulin resistance and the third (small dense LDL). McLaughlin et al. 2003 demonstrated that TG/HDL >3.5 had performance comparable to direct insulin sensitivity testing for detecting insulin resistance — a remarkable finding for a cheap ratio derived from a standard panel. Many clinicians use TG/HDL change as a real-time read on insulin sensitivity, faster than waiting for HbA1c to update.

Limitations and Friedewald caveats

Most US lipid panels calculate LDL using the Friedewald equation: LDL = Total − HDL − (Triglycerides ÷ 5). This breaks down when triglycerides exceed 400 mg/dL (over-estimates LDL) or in certain genetic conditions. If your triglycerides are high, ask for direct LDL measurement (NMR LipoProfile or ApoB) for an accurate number. The 2013 Martin/Hopkins update to Friedewald improves accuracy across a wider range but is not yet universally adopted. Non-HDL cholesterol is reliable regardless of triglyceride level because the calculation only requires total and HDL.

Related tools

• HOMA-IR Insulin Resistance Calculator
• Waist-to-Hip Ratio
• Waist-to-Height Ratio
• A1C ↔ eAG Converter

Frequently asked questions

Which cholesterol ratio matters most?

It depends what you're screening for. For overall CVD risk: TC/HDL ratio is the classic Framingham-derived measure and is still strongly predictive. For insulin resistance and metabolic syndrome: TG/HDL ratio is the highest-yield single marker — McLaughlin 2003 (Annals of Internal Medicine) demonstrated TG/HDL >3.5 mg/dL predicted insulin resistance with sensitivity and specificity comparable to direct measurement. For LDL particle atherogenicity: ApoB or LDL-P particle counts beat any ratio, but they're not on standard panels. For practical use, TC/HDL + TG/HDL together cover most of what ratios can tell you.

My total cholesterol is high but my ratios look good. Is that OK?

Mostly yes — it's exactly why ratios were developed. Total cholesterol over 240 mg/dL with HDL of 80 mg/dL gives TC/HDL of 3.0 — well in the optimal range, low actual cardiovascular risk. Conversely, "normal" total cholesterol of 180 with HDL of 35 gives TC/HDL of 5.1 — high risk despite the unremarkable headline number. The ratios capture the protective effect of HDL and the relative atherogenic load, which is what actually drives plaque formation. Modern lipid guidelines (ACC/AHA 2018) acknowledge this and increasingly emphasise non-HDL cholesterol (total − HDL) as a primary target.

How does TG/HDL ratio relate to insulin resistance?

Very strongly. Insulin resistance drives a characteristic lipid pattern called atherogenic dyslipidemia: elevated triglycerides, reduced HDL, and small dense LDL particles. The TG/HDL ratio captures the first two with a single number. McLaughlin et al. 2003 showed TG/HDL >3.5 (in mg/dL) had sensitivity 64% and specificity 68% for detecting insulin resistance — better than fasting glucose or BMI as a single marker. The ratio is so tightly linked that some clinicians use TG/HDL change as a real-time read on whether dietary interventions are improving insulin sensitivity, even between lab visits.

Should I worry about non-HDL cholesterol?

Yes — it's arguably the most useful single cholesterol number. Non-HDL = total cholesterol − HDL. This captures all the atherogenic apoB-containing particles (LDL, VLDL, IDL, lipoprotein(a)) in one number, while subtracting the protective HDL. The 2018 ACC/AHA guidelines recommend non-HDL targets that are roughly 30 mg/dL higher than corresponding LDL targets (e.g., LDL <100 corresponds to non-HDL <130). Non-HDL is calculated automatically from any standard lipid panel — no extra test needed — and is more reliable than calculated LDL in people with elevated triglycerides (where the Friedewald equation breaks down).

Do statins improve cholesterol ratios?

They dramatically improve LDL-based ratios (TC/HDL, LDL/HDL, non-HDL) by lowering LDL 30–55% at typical doses. They modestly improve HDL (5–10% increase) and triglycerides (10–20% reduction). Stronger triglyceride reduction comes from fibrates, omega-3s, niacin, or — most reliably — weight loss and reduced carbohydrate intake. The 2002 HPS (Heart Protection Study) and dozens of subsequent statin trials show consistent 25–35% reduction in CVD events with statin therapy in appropriate populations, mediated primarily through LDL reduction rather than ratio change per se.