LDL Calculator

The LDL number on your lab report is usually not measured — it is calculated, with a 1972 equation, from three other values. This LDL calculator applies that same Friedewald formula to your total cholesterol, HDL and triglycerides, shows you how the number is built, and explains what your result means against current targets.

Calculate below, then read on: the formula, the LDL ranges, when the calculation breaks down, and what actually lowers LDL.

LDL calculated: how labs really do it

Directly measuring LDL is slow and costly, so most laboratories estimate it with the Friedewald equation:

• LDL = total cholesterol − HDL − (triglycerides ÷ 5) — all in mg/dL. (In mmol/L, triglycerides are divided by 2.2.)

The triglycerides÷5 term estimates VLDL, the other major cholesterol carrier. Total 200, HDL 50, triglycerides 150 → LDL = 200 − 50 − 30 = 120 mg/dL. When you see “LDL calc” or “calculated LDL” on a report, this arithmetic — or one of its modern refinements — is what happened.

LDL cholesterol ranges

Crucially, your personal target depends on your overall risk: after a heart attack or in diabetes, guidelines push LDL below 70 — sometimes below 55 — while a low-risk healthy adult is judged against the ordinary table. The category is general; the target is individual.

When the Friedewald calculation breaks down

The formula’s VLDL shortcut fails in known situations: triglycerides above 400 mg/dL make it invalid (many labs then refuse to report a calculated LDL), non-fasting samples with high triglycerides underestimate LDL, and very low LDL values (below ~70) are estimated poorly — which matters exactly in the high-risk patients targeted that low. Newer equations (Martin-Hopkins, Sampson) and direct LDL assays fix much of this; if your triglycerides run high, ask whether your lab uses one.

How to lower LDL cholesterol

The levers, in rough order of dietary power: replace saturated fat (fatty meat, butter, cream) and all trans fat with unsaturated fats; add soluble fibre daily (oats, beans, psyllium); add plant sterols; lose excess weight; exercise regularly. Together, committed diet change lowers LDL by 10–20%. When genetics set LDL high — familial hypercholesterolemia can hold it above 190 regardless of diet — medication is the effective answer, and statins remain among the best-evidenced drugs in medicine. Context for the whole panel lives in our cholesterol ratio calculator and the hyperlipidemia guide.

Frequently asked questions

What does “LDL calculated” mean on my lab report?

The lab estimated LDL with the Friedewald equation (total − HDL − triglycerides÷5) instead of measuring it directly. It is standard practice and accurate for most people with normal triglycerides.

What is a good LDL level?

Below 100 mg/dL (2.6 mmol/L) is optimal for most adults. People at high cardiovascular risk are treated toward below 70 — or even 55 — by their physicians.

Why is my calculated LDL missing when triglycerides are high?

Above 400 mg/dL of triglycerides, the Friedewald formula becomes unreliable, so labs suppress the calculation and may run a direct LDL measurement instead.

Is calculated LDL as accurate as a direct measurement?

For fasting samples with triglycerides under about 200–400 mg/dL, yes — differences are small. Accuracy degrades with high triglycerides and at very low LDL values.

How fast can LDL come down?

Diet changes show in 6–12 weeks; statins reach most of their effect within a month. Repeat testing is usually scheduled around 8–12 weeks after any change.