LDL cholesterol: normal range, high and low

Q: Why is LDL called “bad” cholesterol?

Because of what it does: excess LDL cholesterol settles into artery walls and, together with other substances, forms the plaque of atherosclerosis. Narrowed heart arteries can cause angina; a fully blocked one causes a heart attack.

Q: What does “calculated” LDL mean on my report?

Most reports estimate LDL from the total cholesterol, HDL, and triglyceride numbers rather than measuring it directly. Both approaches answer the same question, and either way a lower number is better.

Q: Is there such a thing as LDL that is too low?

No lower limit has been set — for LDL, lower numbers are better for heart health. Treatment targets, such as below 70 mg/dL (1.81 mmol/L) for people with heart or vascular disease, are set individually.

In shortBelow 100 mg/dL (2.59 mmol/L) is optimal; from 160 mg/dL (4.14 mmol/L) is high. With heart or vascular disease, the target is below 70 mg/dL (1.81 mmol/L).

Reference ranges

Group	Reference range
Optimal	Less than 100 mg/dL (2.59 mmol/L)
Near optimal / above optimal	100–129 mg/dL (2.59–3.34 mmol/L)
Borderline high	130–159 mg/dL (3.37–4.11 mmol/L)
High	160–189 mg/dL (4.14–4.89 mmol/L)
Very high	190 mg/dL (4.92 mmol/L) and above
Target with heart or vascular disease	Below 70 mg/dL (1.81 mmol/L)
Age 19 or younger	Less than 110 mg/dL (2.85 mmol/L)

Ranges vary slightly among laboratories. If you have coronary artery disease or are at high risk for it, your provider may set a different, lower LDL goal.

Reference range vs optimal — not the same thing

For most adults the goal is below 3.0 mmol/L (<115 mg/dL). With high cardiovascular risk or after a heart attack or stroke, the target is below 1.8 mmol/L (<70 mg/dL).

Check your value

Enter the number from your lab report — see how it compares with the typical range. Mind the units shown in the chosen row.

A rough comparison with a typical range, not a diagnosis. Reference ranges vary between laboratories — check the range on your own report and let a clinician interpret the result.

What this marker is

LDL stands for low-density lipoprotein — a combination of fat and protein that carries cholesterol through the blood. It is sometimes called the “bad” cholesterol because a high LDL level leads to a buildup of cholesterol in the arteries. HDL, its counterpart, carries cholesterol back to the liver for removal.

When there is too much LDL cholesterol in the blood, the extra LDL, along with other substances, forms plaque. The plaque builds up in the arteries — atherosclerosis — hardening and narrowing them. In the arteries of the heart this is coronary artery disease: slowed or blocked blood flow can cause chest pain (angina), and a complete blockage causes a heart attack.

The LDL on a report may be marked “calculated” — an estimate derived from total cholesterol, HDL, and triglycerides — or measured “directly” from the blood sample. Either way, the lower the LDL number, the better for the arteries.

LDL is measured within the lipid profile, so the preparation is the panel's: no food for 9 to 12 hours before the draw. How often the test is worth repeating depends on age, risk factors, and family history — general recommendations run from the first test at ages 9–11 to checks every 1–2 years for men 45–65 and women 55–65.

Calculator: LDL by Friedewald and non-HDL

Enter total cholesterol, HDL and fasting triglycerides from your report (mg/dL).

LDL = TC − HDL − TG/5 (mg/dL); non-HDL = TC − HDL. Friedewald is valid when TG < 400 mg/dL and the sample was fasting. Everything runs in your browser.

When it is high

The atherosclerosis pathwayHigh LDL is less a diagnosis than a mechanism: the excess cholesterol settles into artery walls as plaque, narrowing the vessels of the heart and brain.

Everyday driversThe same factors that raise total cholesterol — saturated fats, inactivity, excess weight, smoking context, diabetes — raise LDL with it.

Familial lipid disordersInherited conditions with high blood cholesterol and triglycerides produce high LDL from early life, which is why family history changes the testing schedule.

When it is low

Lower is betterFor LDL, researchers have not set a lower limit — as low as it goes is generally considered good for heart health.

What can skew the result

These factors can shift the value without any disease — worth considering before a retest:

Food within 9–12 hours before the testDiet, weight, physical activityCertain medicines and supplementsFamily history

How to prepare

LDL is measured within the lipid profile: no food for 9 to 12 hours before the draw. Tell your provider about all medicines and supplements you take.

When a retest makes sense

How often to repeat depends on age, risk factors, and family history: younger adults roughly every 5 years, men 45–65 and women 55–65 every 1–2 years. During cholesterol treatment the level is rechecked against the personal target.

Who usually reviews this result

A result outside the reference range is usually reviewed by: your GP or primary care doctor; a cardiologist if cardiovascular risk is the concern. Bring your lab report and any previous results to the appointment.

Names used on lab reports

Your report may use any of these names:
LDLLDL cholesterolLow-density lipoproteinBad cholesterol

Units and conversion

Measured in: mg/dL

mg/dL = mmol/L

mg/dL × 0.0259 = mmol/L. Example: 100 mg/dL = 2.59 mmol/L. Results are rounded to 2 decimal places.

Several markers on your report?

See how MedProtect explains results in the app: the whole report, a check of the recognized values, and a clear breakdown.

Get your results explained See an example

Frequently asked questions

Why is LDL called “bad” cholesterol?