Article — Cholesterol Ratio Calculator
Cholesterol ratio calculator: total/HDL, LDL/HDL, and what the numbers mean
The total cholesterol to HDL ratio target is below 5.0 (with below 3.5 considered ideal), and below 3.5 is ideal. For LDL to HDL, below 3.5 is acceptable and below 2.0 is the optimal range. The triglyceride to HDL ratio should sit below 2.0 (mg/dL). These ratios screen cardiovascular risk better than any single lipid value, but they remain screening signals — not treatment triggers.
The calculator above takes total cholesterol and HDL, with optional LDL and triglycerides, and returns all four standard ratios plus non-HDL cholesterol. When LDL is missing, the Friedewald equation fills it in. The rest of this article explains where each cut-off comes from and how clinicians read them.
Medical disclaimer: This calculator is an educational tool. It does not provide medical advice or replace assessment by a clinician. Cholesterol values, ratios, and any treatment decisions belong to a conversation with your doctor.
What is the cholesterol ratio?
A cholesterol ratio is the relationship between two lipid measurements from a standard fasting lipid panel. The most common is total cholesterol divided by HDL, written TC/HDL. Lower is better. The ratio captures the balance between cholesterol that drives atherosclerosis (LDL, VLDL) and the protective HDL fraction that ferries cholesterol back to the liver.
The reason ratios matter: two people with the same total cholesterol can have very different cardiovascular risk depending on how much of that total is HDL. A total of 220 with HDL of 70 (ratio 3.1) is far less concerning than a total of 200 with HDL of 35 (ratio 5.7), even though the second person looks "better" on the total cholesterol number alone.
Total/HDL cholesterol ratio
TC/HDL is the most-cited cholesterol ratio. The American Heart Association generally accepts a ratio below 5.0, prefers below 3.5, and treats ratios above 5.0 as a marker for elevated cardiovascular risk that warrants further workup.
TC/HDL = Total ÷ HDL (same units both sides)200 ÷ 50 = 4.0 (acceptable)240 ÷ 35 = 6.9 (high)The Framingham Heart Study, running since 1948, was the first large cohort to validate this ratio. Across hundreds of thousands of person-years, TC/HDL predicted coronary events more accurately than total cholesterol alone, with predictive power comparable to LDL.
LDL/HDL cholesterol ratio
LDL/HDL compares the most atherogenic lipoprotein directly against the protective one. Targets: below 2.0 is ideal, below 3.5 is acceptable, and above 5.0 is associated with substantially elevated risk. The ratio is sometimes called the cardiac risk ratio.
- < 2.0 — ideal; rarely achieved without favorable genetics or lifestyle
- 2.0–3.5 — acceptable; population norm in healthy adults
- 3.5–5.0 — high; clinical review recommended
- > 5.0 — very high; ASCVD risk assessment and clinician follow-up
The ratio is meaningful only when LDL is measured or estimated reliably. Direct LDL assay is standard at most modern labs; older panels rely on the Friedewald estimate (covered below). When triglycerides exceed 400 mg/dL, neither estimate is trustworthy and a direct LDL is required.
Triglyceride/HDL ratio
The triglyceride/HDL ratio (TG/HDL) is a newer screening tool that captures something different from the cholesterol ratios. It is a marker for insulin resistance and the small-dense LDL pattern — a particle profile linked to higher cardiovascular risk even when LDL itself looks normal.
A 2003 study in the journal Circulation reported a 16-fold increase in myocardial infarction risk for patients with TG/HDL ratios above 7.5 compared with those below 1.8, after adjusting for total cholesterol. The TG/HDL ratio captured risk that the standard lipid panel missed. The cutoff for concern, by most North American references, is 2.0 in mg/dL units (about 0.87 in mmol/L).
TG/HDL converts cleanly between mg/dL and mmol/L only with care: triglycerides and cholesterol use different molar masses, so the ratio in mmol/L differs from the mg/dL ratio by roughly 2.3×. Mind the unit when comparing across labs.
Non-HDL cholesterol
Non-HDL cholesterol is total cholesterol minus HDL. The number captures every atherogenic lipoprotein in one figure: LDL, VLDL, IDL, lipoprotein(a), and any other apoB-carrying particle. The 2018 AHA/ACC guideline names non-HDL a secondary treatment target alongside LDL, especially when triglycerides run high and Friedewald becomes unreliable.
The non-HDL target sits about 30 mg/dL above the LDL target. The 30-point gap is the average contribution of VLDL cholesterol — at a typical triglyceride level of 150 mg/dL, VLDL chol is roughly 150/5 = 30 mg/dL.
Friedewald LDL estimation
The Friedewald equation, published in 1972 by Friedewald, Levy, and Fredrickson, estimates LDL when only total cholesterol, HDL, and triglycerides are measured directly.
LDL = Total − HDL − Triglycerides/5 (mg/dL). In mmol/L the divisor is 2.2. The equation rests on two assumptions: nearly all serum triglycerides are carried on VLDL, and the VLDL triglyceride-to-cholesterol ratio is stable at 5:1 (mg/dL). Both hold reasonably well at triglyceride levels below 400 mg/dL, and break down above that.
Do not trust the Friedewald LDL when triglycerides exceed 400 mg/dL — the assumption that VLDL = TG/5 fails. The Martin-Hopkins method, published in 2013 in JAMA, replaces the fixed divisor with an adjustable one based on TG and non-HDL, improving accuracy at elevated triglyceride levels. Most modern labs now use a direct LDL assay regardless.
How to improve your cholesterol ratio
Cholesterol ratios improve when HDL rises, LDL falls, or both. The mechanisms differ enough to be worth separating.
Aerobic exercise — 150 minutes per week of brisk activity — raises HDL by 5 to 10% in most adults, per the AHA. Combine that with a 7% body weight reduction and TG/HDL ratios often drop by a quarter, with the largest changes in people who start with the worst ratios.
Diet changes that lower LDL: reduce saturated fat to under 6% of calories, increase soluble fiber from oats, beans, and apples, and add plant sterols. Statin therapy reduces LDL by 30–60% depending on dose and drug, with proportional improvements in TC/HDL and LDL/HDL ratios. Talk to a clinician before starting or stopping any cholesterol-lowering medication.
Common cholesterol ratio mistakes
- Comparing ratios across unit systems — TC/HDL in mg/dL equals TC/HDL in mmol/L (same units cancel), but TG/HDL does not because triglycerides and cholesterol use different molar masses
- Treating Friedewald LDL as exact — error grows with rising triglycerides; above 400 mg/dL the estimate is unreliable
- Reading a ratio without context — age, blood pressure, smoking, and diabetes all change what a given ratio means clinically
- Non-fasting samples for TG/HDL — a recent meal elevates triglycerides, inflating the TG/HDL ratio for several hours
- Ignoring trend — a stable ratio of 4.0 is very different from a ratio of 4.0 that has been climbing for three years
- Self-treating — cholesterol ratios are one input among many in cardiovascular risk; treatment decisions need a clinician