LDL Cholesterol & Lipid Ratio Calculator
LDL, non-HDL cholesterol and ratios from total cholesterol, HDL and triglycerides.
Enter your total cholesterol, HDL and triglycerides.
LDL cholesterol by each equation
| Equation | LDL-C |
|---|
NCEP ATP III categories
| Value | Yours | Category |
|---|
All ATP III cut-offs in mg/dL
For general information only, not medical advice. Consult a qualified health professional for advice about your situation.
About the LDL Cholesterol & Lipid Ratio Calculator
Most lipid reports measure total cholesterol, HDL cholesterol and triglycerides and then calculate LDL cholesterol. This calculator does that calculation two ways — the classic Friedewald equation and the newer Sampson (NIH) equation, which stays accurate at higher triglyceride levels — and adds non-HDL cholesterol, the total/HDL and TG/HDL ratios, and the NCEP ATP III category of each value.
Enter the numbers in mg/dL or mmol/L, exactly as printed on your report. The tool tells you when an equation is not valid for your values (for example Friedewald at triglycerides of 400 mg/dL or more) instead of showing a misleading number.
How to use it
- Choose the unit printed on your lab report: mg/dL or mmol/L.
- Enter total cholesterol, HDL cholesterol and triglycerides.
- Read the LDL cholesterol from both equations, non-HDL cholesterol and the two ratios. The coloured labels are the NCEP ATP III categories.
- Use Copy result to keep the numbers or share them with your doctor.
Examples
Friedewald LDL 120 mg/dL · Sampson LDL 123 mg/dL (near or above optimal) · non-HDL 150 mg/dL · TC/HDL 4.00 · TG/HDL 3.00
Friedewald not valid (triglycerides 400 or more) · Sampson LDL 113 mg/dL · non-HDL 200 mg/dL · triglycerides very high
Friedewald LDL 3.12 mmol/L · Sampson LDL 3.21 mmol/L · non-HDL 3.90 mmol/L · TC/HDL 4.00
Common uses
- Checking the LDL value on a lab report, or calculating it when the report gives only total cholesterol, HDL and triglycerides.
- Seeing how much the Friedewald and Sampson equations differ for your numbers, especially with high triglycerides.
- Converting a lipid panel between mg/dL and mmol/L.
The two equations
Friedewald, with every value in mg/dL:
- LDL-C = total cholesterol − HDL-C − triglycerides ÷ 5
The "triglycerides ÷ 5" term estimates the cholesterol carried in VLDL. It is not valid when triglycerides are 400 mg/dL (4.52 mmol/L) or more, and it tends to read too low when LDL cholesterol is low.
Sampson (NIH equation 2), also in mg/dL:
- LDL-C = TC ÷ 0.948 − HDL-C ÷ 0.971 − (TG ÷ 8.56 + TG × non-HDL-C ÷ 2140 − TG² ÷ 16 100) − 9.44
It was derived from reference-method (β-quantification) measurements at the NIH Clinical Center and validated in more than 250 000 samples. In that study it was more accurate than Friedewald, particularly with high triglycerides, and it can be used up to 800 mg/dL (9.03 mmol/L). Above that, neither equation is reliable and a directly measured LDL cholesterol is needed.
Values entered in mmol/L are converted with 1 mmol/L = 38.67 mg/dL for cholesterol and 88.57 mg/dL for triglycerides, calculated in mg/dL and converted back.
NCEP ATP III categories (mg/dL)
- LDL cholesterol: below 100 optimal · 100–129 near or above optimal · 130–159 borderline high · 160–189 high · 190 or more very high
- Total cholesterol: below 200 desirable · 200–239 borderline high · 240 or more high
- HDL cholesterol: below 40 low · 60 or more high
- Triglycerides: below 150 normal · 150–199 borderline high · 200–499 high · 500 or more very high
In mmol/L the tool converts the same cut-offs (for example LDL 100 mg/dL = 2.59 mmol/L). A value is classed as it is shown, so an LDL of 129.6 mg/dL appears as 130 and is borderline high — as a lab would report it.
Non-HDL cholesterol and the ratios
Non-HDL cholesterol (total minus HDL) is all the cholesterol carried by particles that can build up in artery walls, including VLDL and remnants — useful when triglycerides are high. ATP III set its goals 30 mg/dL above the LDL goals: below 130 mg/dL when the LDL goal is below 100, below 160 for an LDL goal below 130, and below 190 for an LDL goal below 160.
The total/HDL ratio is the same in both units; a lower ratio is better. The TG/HDL ratio depends on the unit: the mg/dL ratio is about 2.3 times the mmol/L ratio, so the tool shows both. There is no guideline cut-off for it; studies use it as a rough marker of insulin resistance, with thresholds that differ between populations.
Sources
- Friedewald WT, Levy RI, Fredrickson DS. Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge. Clinical Chemistry
- Sampson M et al. A new equation for calculation of low-density lipoprotein cholesterol in patients with normolipidemia and/or hypertriglyceridemia. JAMA Cardiology
- National Heart, Lung, and Blood Institute. ATP III At-a-Glance: Quick Desk Reference
- ACC/AHA multisociety guideline on the management of dyslipidemia, which replaced the earlier cholesterol guideline
Limitations
- A calculated LDL is an estimate. With triglycerides above 800 mg/dL (9.03 mmol/L), in rare lipid disorders such as type III hyperlipoproteinaemia, or when the equations give zero or less, ask for a directly measured LDL cholesterol.
- Some laboratories use the Martin–Hopkins method, which takes its factor from a 180-cell table; it is not included here, so your report can differ slightly.
- ATP III categories describe the values, not your heart risk. Current guidelines base treatment on your overall risk — see the 10-year heart disease risk calculator.
- The categories are for adults; children and teenagers have different cut-offs.
Privacy
Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.
Frequently asked questions
Which LDL value should I use, Friedewald or Sampson?
With triglycerides below 200 mg/dL the two usually differ by only a few mg/dL. At higher triglycerides the Sampson (NIH) equation is more accurate, and from 400 mg/dL only Sampson is valid. The categories on this page use the Sampson value when it is valid. Your lab may report a third method (Martin–Hopkins) or a direct measurement — use the value your doctor uses for your treatment decisions.
Why is my lab’s LDL different from this result?
Labs differ in the equation they use (Friedewald, Martin–Hopkins, Sampson) or measure LDL directly, and they round to whole mg/dL or one or two decimals in mmol/L. A difference of a few units is normal.
Do I need to fast before a lipid test?
The Friedewald equation was developed on fasting samples. In the NIH study behind the Sampson equation, its results were nearly identical in fasting and non-fasting samples. Follow your doctor’s or laboratory’s instructions.
What is non-HDL cholesterol?
Total cholesterol minus HDL cholesterol: the cholesterol in all the particles that can contribute to plaque, not just LDL. It needs no triglyceride correction, so it is useful when triglycerides are high. ATP III set its goals 30 mg/dL above the LDL goals.
How do I convert cholesterol from mmol/L to mg/dL?
Multiply cholesterol (total, HDL, LDL, non-HDL) by 38.67 and triglycerides by 88.57. To go back, divide. For example 5.0 mmol/L total cholesterol is 193 mg/dL.
Are my results sent anywhere?
No. The calculation runs entirely in your browser; the numbers you type never leave your device.