This LDL calculator estimates the LDL value based on the cholesterol blood test results (total, HDL cholesterol levels & triglycerides) by using the Friedewald and Iranian formulas. Discover more about LDL levels and their implications on your health below the form.

Total Cholesterol (TC):*
HDL Cholesterol:*
Triglycerides (TG):*
Total Cholesterol (TC):*
HDL Cholesterol:*
Triglycerides (TG):*

How does this LDL calculator work?

This health tool computes the LDL cholesterol value from the total cholesterol, HDL, triglyceride levels according to the two formulas used in these cases: the Friedewald (1972) and Iranian study (2008). The second formula is often recommended when the triglyceride levels are lower than average, as in the case of those with a low carbohydrate diet.

For your convenience, the LDL calculator allows you to enter the three values in either mg/dL (see first tab) or mmol/L (see second tab). You will be given the two results in the corresponding measurement unit so that you can further on interpret the results easily.

■ In case of the 1st tab "LDL in mg/dL" these are the equations used:

- The Friedewald formula: LDL = TC - HDL – TG / 5.0 (mg/dL)

- The Iranian study formula: LDL = TC / 1.19 + TG / 1.9 – HDL / 1.1 – 38 (mg/dL)

■ In case of the 2nd tab "LDL in mmol/L" these are the formulas behind the algorithm:

- The Friedewald equation: LDL = TC - HDL – TG / 2.17 (mmol/L)

- The Iranian study method: LDL = TC / 1.19 + TG / 0.81 – HDL / 1.1 – 0.98 (mmol/L) 

Example calculation

Let’s take the case of an individual with the following cholesterol blood test results:

TC – 215 mg/dL; HDL – 80 mg/dL; Triglycerides – 52 mg/dL

The result is:

LDL cholesterol by Friedewald approach is 124.60 mg/dL.

LDL cholesterol by Iranian method is 97.31 mg/dL. 

LDL medical implications

Cholesterol is a steroid which is a chemical substance classified as lipid or fat. It is a component of cell membranes and is a precursor to various hormones and to vitamin D. Some of it comes from the diet and some is synthesized in the liver. Since cholesterol cannot dissolve in the blood, it needs carriers to move through the bloodstream. These carriers are lipoproteins made of fat and protein.

There are two varieties, the low density one LDL (because the particles tend to be less dense) and the high density one HDL. The first is considered the bad one as in high amounts; it tends to collect in the walls of blood vessels causing their narrowing and atherosclerosis. Beside the danger of arterial blockage, the cholesterol plaque formed can rupture and turn into a blood clot who can in turn lead to a heart attack.

HDL is the good cholesterol as it helps remove the LDL one from the arteries and takes it back to the liver. This is why high levels of HDL are indicated and are said to protect against heart attack and stroke. 

LDL testing

Getting your LDL checked every five years and even more often if there is a family history of hypercholesterolemia, allows you to monitor and control the cholesterol level and reduce the risk of developing a heart disease. This is basically a simple blood test that measures the LDL, HDL cholesterol and one fifth of the triglyceride level, also showing the total cholesterol count.

There are also several risk assessment techniques that determine the percentage target of LDL as to avoid the risk of hear disease or stroke in the following decade.

Lowering LDL cholesterol

Trying to diminish the risk for the consequences high levels of LDL carry should start with some lifestyle changes in diet and taking on an exercise regime. An LDL cholesterol lowering diet that is low in saturated fat and adding fiber are the first steps to take.

It has been discovered that exercise not only helps lower LDL but can also influence the formation of HDL, the good cholesterol. Smoking, diabetes or high blood pressure are also considered risk factors. In serious cases, medication will be required and this is made through statins, niacin, fibrates or bile acid sequestrants.


1) Lecerf JM, de Lorgeril M. (2011) Dietary cholesterol: from physiology to cardiovascular risk. Br J Nutr; 106 (1): 6–14

2) National Health Service. (2014) High Cholesterol levels.

22 May, 2015