Cholesterol Ratio Calculator

The cholesterol ratio in brief

The cholesterol ratio – more precisely the total cholesterol to HDL cholesterol ratio (TC:HDL) – divides your total cholesterol by your HDL ("good") cholesterol. It summarises the balance between cholesterol carried in particles that can clog arteries and cholesterol carried by HDL particles. A lower ratio is better.

The calculator above works with any unit, because the ratio has no units: as long as both values are in mg/dL, or both in mmol/L, the answer is the same. For example, total cholesterol 200 mg/dL and HDL 50 mg/dL give a ratio of 4.0 – and so do 5.17 mmol/L and 1.29 mmol/L.

Commonly used interpretation bands are:

• below 3.5 – ideal
• 3.5 to 5.0 – acceptable, though lower is better
• above 5.0 – associated with higher cardiovascular risk

The ratio is used in several risk calculators, including QRISK3 in the UK, and is widely printed on lipid reports. On its own, however, it is less informative than knowing your LDL or non-HDL cholesterol and your overall risk.

How to calculate the ratio

Cholesterol ratio = total cholesterol ÷ HDL cholesterol

Notice that two people with the same total cholesterol can have very different ratios. Someone with total cholesterol of 220 mg/dL and HDL of 80 mg/dL has a ratio of 2.75, while someone with the same total and HDL of 35 mg/dL has a ratio of 6.3. This is the main reason the ratio exists: total cholesterol alone hides the composition.

Related ratios

• LDL:HDL ratio – LDL divided by HDL. Values below about 2.5–3.0 are often described as favourable. It is used less often than TC:HDL.
• Triglyceride:HDL ratio – triglycerides divided by HDL. In mg/dL, a value above about 3 has been associated with insulin resistance and small, dense LDL particles, though cut-offs differ by ethnicity. In mmol/L, the equivalent cut-off is about 1.3.
• ApoB:apoA-I ratio – the ratio of atherogenic to anti-atherogenic particle proteins. It was a strong predictor of heart attack in the INTERHEART study but requires specialised tests.

Understanding the two numbers

Total cholesterol

Total cholesterol is the sum of cholesterol carried in all lipoprotein particles in the blood. Cholesterol itself is essential: it forms part of every cell membrane and is the starting material for steroid hormones, vitamin D and bile acids. Most of it is made by the liver rather than eaten. Problems arise when too much circulates in particles that can enter artery walls.

Typical adult reference values are a desirable total cholesterol below 200 mg/dL (5.2 mmol/L), borderline high at 200–239 mg/dL (5.2–6.1 mmol/L) and high at 240 mg/dL (6.2 mmol/L) or above. The NHS uses a healthy total cholesterol of 5 mmol/L or lower.

HDL cholesterol

HDL (high-density lipoprotein) particles collect excess cholesterol from tissues, including artery walls, and return it to the liver – a process called reverse cholesterol transport. Higher HDL levels are associated with lower cardiovascular risk in population studies. Typical desirable levels are above 40 mg/dL (1.0 mmol/L) for men and above 50 mg/dL (1.3 mmol/L) for women, with 60 mg/dL (1.6 mmol/L) or higher often described as protective.

Research over the past 15 years has refined this picture. HDL cholesterol measures how much cholesterol HDL particles carry, not how well they work. Genetic studies suggest that HDL cholesterol itself may not be causal, and that HDL function – its ability to remove cholesterol and reduce inflammation – may matter more than the amount. Low HDL often travels with other risk factors (high triglycerides, insulin resistance, smoking and inactivity), which partly explains its association with heart disease.

Calculating the ratio in mmol/L

If your results are in mmol/L, divide directly. For total cholesterol 5.8 mmol/L and HDL 1.1 mmol/L, the ratio is 5.8 ÷ 1.1 = 5.3. You do not need to convert to mg/dL first – the answer is identical because both values share the same conversion factor.

Why the ratio is used

A simple summary of balance

Total cholesterol includes cholesterol in LDL, VLDL, remnant particles, lipoprotein(a) and HDL. The first group is atherogenic; HDL is not. Dividing by HDL creates a single number that rises when atherogenic cholesterol is high and falls when HDL is high.

Risk prediction

In large population studies, the TC:HDL ratio predicted coronary heart disease better than total cholesterol or LDL cholesterol alone. A major analysis by the Prospective Studies Collaboration, combining data from 61 cohorts with almost 900,000 adults, found that the ratio was a stronger predictor of death from ischaemic heart disease than either total or HDL cholesterol alone. For this reason, the ratio is an input in QRISK3, the risk calculator used in UK primary care.

Communicating risk

A single ratio is easy to track and explain. Many people find "your ratio is 5.6, ideally it would be under 4" easier to understand than separate numbers.

A brief history

The idea of combining total and HDL cholesterol into a ratio grew out of the Framingham Heart Study, which began in 1948 in Massachusetts. By the 1970s, Framingham investigators had shown that low HDL was a strong, independent predictor of coronary heart disease, and in the 1980s and 1990s they proposed the TC:HDL ratio as a simple way to combine the two measures. Ratios of about 5.0 in men and 4.4 in women were described as "average risk" in that population. Since then, guidelines have moved towards targeting LDL and non-HDL cholesterol, but the ratio has remained part of risk calculators and lab reports because it is simple and predictive.

Limitations of the ratio

The ratio is useful but has important limits:

• It hides the absolute level. A total cholesterol of 300 mg/dL with HDL 100 mg/dL gives a ratio of 3.0, which looks ideal, yet an LDL near 190 mg/dL may indicate familial hypercholesterolaemia and require treatment.
• HDL is not a treatment target. Raising HDL with medicines (niacin, CETP inhibitors) did not reduce cardiovascular events in large trials, so improving the ratio by raising HDL alone is not the goal.
• Very high HDL is not always protective. Extremely high HDL levels, above about 100 mg/dL (2.6 mmol/L), have been linked in some studies to higher, not lower, mortality, and may reflect genetic variants or high alcohol intake.
• Treatment goals use LDL or non-HDL. Major guidelines set targets for LDL or non-HDL cholesterol, not the ratio.

For these reasons, clinicians treat the ratio as one input among several rather than as a target in itself.

Ranges by age and sex

The ratio differs between men and women, mainly because women tend to have higher HDL:

Some older sources quote sex-specific "average risk" ratios of about 5.0 for men and 4.4 for women, derived from the Framingham study. These are population averages, not targets: being average in a population with a high rate of heart disease is not ideal.

What affects your ratio

Things that raise the ratio

• Low HDL: caused by smoking, physical inactivity, excess weight, insulin resistance, type 2 diabetes, high-carbohydrate diets, some medicines (such as anabolic steroids and some beta-blockers) and genetic factors
• High total cholesterol: caused by diet, genetics, hypothyroidism, kidney disease and some medicines
• High triglycerides, which tend to lower HDL and raise atherogenic cholesterol simultaneously

Things that lower the ratio

• Stopping smoking – HDL rises within weeks to months
• Regular aerobic exercise – modestly raises HDL and lowers triglycerides
• Weight loss – lowers triglycerides and LDL; HDL rises after weight stabilises
• Replacing saturated and trans fats with unsaturated fats
• Reducing refined carbohydrate and sugar
• Statins and other LDL-lowering medicines, which lower total cholesterol substantially

Using the ratio in risk assessment

Cardiovascular risk calculators combine lipids with other risk factors:

These calculators estimate the chance of a heart attack or stroke over the next 10 years (and, for some, 30 years). They also consider age, sex, blood pressure, smoking, diabetes, kidney function and, in QRISK3, ethnicity, deprivation, family history and several medical conditions. Your ratio contributes to the result but rarely decides it alone.

An example

Two 55-year-old women both have a ratio of 4.5. One smokes, has high blood pressure and diabetes; the other does not. Their 10-year risks can differ several-fold. That is why guidelines recommend looking at the whole picture instead of treating a ratio threshold.

The ratio in specific groups

People with diabetes

Type 2 diabetes is often accompanied by low HDL and raised triglycerides, which push the ratio up even when LDL is moderate. Because diabetes itself increases cardiovascular risk, most adults with diabetes aged 40–75 are offered a statin regardless of their ratio. Good glucose control helps lower triglycerides; you can check yours with our A1C calculator.

Women before and after menopause

Before menopause, oestrogen helps keep HDL higher and LDL lower, so women's ratios are typically lower than men's. After menopause, LDL tends to rise by about 10–20% and the ratio increases. Hormone therapy is not recommended for the purpose of improving cholesterol.

Older adults

The ratio remains associated with risk in older age, but the strength of the association weakens, partly because other conditions become more important. Decisions about statins in people over 75 depend more on overall health, frailty and preferences than on a ratio threshold.

South Asian populations

People of South Asian ancestry tend to have lower HDL and higher triglycerides at a given body weight, and higher cardiovascular risk. QRISK3 accounts for ethnicity, and some guidelines treat South Asian ancestry as a risk-enhancing factor.

Tracking your ratio over time

A single ratio is a snapshot. When monitoring changes:

• compare results from the same laboratory if possible
• remember that total cholesterol varies by a few percent from day to day, and HDL by a similar amount
• look for changes of more than about 10% before concluding something has really changed
• note any changes in medicines, weight, smoking and alcohol between tests

For example, a man whose ratio falls from 6.0 (total 6.6, HDL 1.1 mmol/L) to 4.2 (total 4.6, HDL 1.1 mmol/L) after starting a statin has achieved a meaningful improvement entirely through lowering atherogenic cholesterol – which is what reduces risk.

Improving your ratio: a realistic plan

1. Get a baseline lipid panel, which does not need to be fasting.
2. Address smoking – the single most effective change for HDL and for overall risk.
3. Build activity gradually towards at least 150 minutes of moderate exercise a week.
4. Adjust your diet: more vegetables, legumes, whole grains, nuts, fish and olive oil; less processed meat, butter, pastries and sugary drinks.
5. Limit alcohol – moderate amounts slightly raise HDL, but this does not reduce risk overall, and heavy drinking raises triglycerides and blood pressure.
6. Discuss medication if your overall risk is high; statins lower total cholesterol and therefore the ratio.
7. Recheck after 3 months of changes.

When to see a doctor

See a clinician if your ratio is above 5.0, if your total cholesterol is 240 mg/dL (6.2 mmol/L) or higher, if your LDL is 160 mg/dL (4.1 mmol/L) or higher, or if your HDL is very low (below 40 mg/dL or 1.0 mmol/L in men, or 50 mg/dL or 1.3 mmol/L in women). Also seek advice if you have a family history of early heart disease or of very high cholesterol, or if you have diabetes, kidney disease or high blood pressure. Your clinician can calculate your overall risk and discuss whether treatment would help.

Seek emergency care for chest pain or pressure, shortness of breath, or symptoms of stroke.