LDL (Friedewald) Calculator

How the Friedewald Formula Works

The Friedewald equation estimates LDL cholesterol as total cholesterol minus HDL minus triglycerides divided by five. That last term approximates VLDL cholesterol, assuming a fixed ratio of triglycerides to VLDL. It is the calculation most standard lipid panels have used for decades, which is why an LDL value often appears on a report even though it was never measured directly.

The assumption breaks down at high triglyceride levels. Above 400 mg/dL the formula is not valid, and it also underestimates LDL when triglycerides are elevated or LDL is very low. In those cases a direct LDL measurement or the newer Martin Hopkins calculation is more reliable.

Reading Your LDL Number

General reference ranges place under 100 mg/dL as optimal, 100 to 129 as near optimal, 130 to 159 as borderline high, 160 to 189 as high, and 190 or above as very high. Those bands apply to people without established cardiovascular disease.

Treatment targets are individual. Someone who has had a heart attack, stroke, or stent is often given a target under 70 mg/dL, and sometimes under 55 in very high risk cases. Diabetes, chronic kidney disease, smoking, high blood pressure, and family history all shift the target downward, which is why two people with the same LDL can get very different advice.

What Else Belongs on the Report

LDL alone gives an incomplete picture of cardiovascular risk. Ask about these companion numbers:

• Non HDL cholesterol: total minus HDL, which captures all atherogenic particles and needs no fasting
• Apolipoprotein B: a direct count of atherogenic particles and a stronger predictor than LDL in many people
• Lipoprotein(a): largely genetic, measured once in a lifetime, and a meaningful risk modifier
• Triglycerides and HDL: the pair that shapes metabolic risk alongside LDL

Lowering LDL

Diet changes typically move LDL by 5 to 15 percent. The most effective steps are cutting saturated fat, adding 10 to 25 grams of soluble fiber from oats, beans, barley, and psyllium, and including plant sterols. Regular aerobic exercise and weight loss help more with triglycerides and HDL than with LDL directly.

Statins remain the most effective LDL lowering therapy, commonly reducing it by 30 to 50 percent, with ezetimibe and PCSK9 inhibitors available when statins are not enough or not tolerated. Recheck a lipid panel roughly 6 to 12 weeks after any change in diet or medication, since that is how long it takes for a new level to stabilize.