LDL Calculator
Estimate LDL cholesterol from a standard lipid panel with the Friedewald equation. Enter total cholesterol, HDL, and triglycerides in mg/dL (or switch to mmol/L) to get LDL, non-HDL, and a category band.
Example: with Total cholesterol 200 · HDL cholesterol 50 · Triglycerides 150 · Units mg/dL (US) → Estimated LDL cholesterol: 120 mg/dL.
- Non-HDL cholesterol150 mg/dL
- LDL categoryNear optimal (100–129 mg/dL)
Computed by the calculator below using its default values. Change any input to see your own numbers.
Friedewald: LDL = Total − HDL − Triglycerides/5 (mg/dL), or /2.2 in mmol/L. Not valid when triglycerides reach 400 mg/dL (4.5 mmol/L).
How the Friedewald estimate works
Most lab panels do not measure LDL directly — they measure total cholesterol, HDL, and triglycerides, then back out LDL. The Friedewald equation subtracts HDL and an estimate of VLDL cholesterol from the total. VLDL is approximated as triglycerides divided by five in mg/dL, a ratio that holds reasonably well at ordinary triglyceride levels.
That divide-by-five shortcut is also the equation's weak spot. When triglycerides climb past about 400 mg/dL, the VLDL estimate breaks down and the formula is no longer valid, which is why a direct or Martin-Hopkins LDL is preferred in that range and after a non-fasting draw.
Why non-HDL is worth a look too
Non-HDL cholesterol is just total minus HDL, and it captures every atherogenic particle — LDL plus VLDL and remnants. Because it does not rely on the triglyceride estimate, it stays reliable when Friedewald LDL wobbles. Many guidelines now treat non-HDL as a co-target, so this page reports both.
How it’s calculated
Friedewald: LDL = Total cholesterol − HDL − (Triglycerides ÷ 5) in mg/dL, or ÷ 2.2 in mmol/L. Non-HDL = Total − HDL. Category thresholds use the NCEP ATP III LDL bands (optimal <100, near optimal 100–129, borderline 130–159, high 160–189, very high ≥190 mg/dL); mmol/L results are converted at 38.67 mg/dL per mmol/L for banding.
Assumes a fasting sample and triglycerides below 400 mg/dL (4.5 mmol/L). Above that, or with type III dyslipidemia, the estimate is unreliable — use a direct LDL. Educational only, not medical advice.
LDL cholesterol categories (mg/dL)
| LDL level | Category |
|---|---|
| Under 100 | Optimal |
| 100–129 | Near optimal / above optimal |
| 130–159 | Borderline high |
| 160–189 | High |
| 190 and above | Very high |
Source: NCEP ATP III LDL cholesterol classification.
Common mistakes
- Using the equation when triglycerides are 400 mg/dL or higher — the LDL estimate is invalid there.
- Mixing units: the VLDL divisor is 5 for mg/dL but 2.2 for mmol/L.
- Estimating LDL from a non-fasting panel, which inflates triglycerides and understates LDL.
- Chasing LDL alone and ignoring non-HDL, which better reflects total atherogenic risk.
Frequently asked questions
What is the Friedewald LDL formula?
LDL equals total cholesterol minus HDL minus triglycerides divided by five, using mg/dL. For example, 200 − 50 − 150/5 gives an LDL of 120 mg/dL. In mmol/L, divide triglycerides by 2.2 instead.
When is the calculated LDL not reliable?
When triglycerides reach 400 mg/dL (about 4.5 mmol/L) or the sample was not fasting. In those cases the VLDL estimate is off, and a directly measured LDL is more accurate.
What is non-HDL cholesterol and why show it?
Non-HDL is total cholesterol minus HDL, capturing all cholesterol-carrying particles that drive plaque. It stays valid even when triglycerides are high, so it is a useful backup to calculated LDL.
What LDL level is considered high?
Under 100 mg/dL is optimal, 130–159 is borderline high, and 190 or above is very high. Your personal target depends on overall cardiovascular risk, which a clinician sets.
Should I change my treatment based on this number?
No. Use it to understand your panel, then discuss targets and any medication with your doctor, who weighs your full risk profile rather than one value.