LDL calculator

What LDL is, and why it is calculated

LDL cholesterol is the “bad” cholesterol: LDL particles carry cholesterol into artery walls, where it builds up as plaque. A standard lipid profile measures total cholesterol, HDL and triglycerides directly, and then calculates LDL from them, because measuring LDL directly costs more. This tool does the same calculation, so you can check your report, see how the methods differ and follow your numbers over time.

How to use this tool

1. Pick the units on your report: mg/dL (most Indian labs) or mmol/L.
2. Type total cholesterol, HDL and triglycerides. Decimals are fine.
3. Read your LDL, its band and your non-HDL cholesterol.
4. Turn on My target to see the target for your health group, Pick the method to switch to Friedewald, Lab’s direct LDL to compare a measured value, or Earlier reports for a trend.

The two methods

Friedewald (1972): LDL = total − HDL − triglycerides ÷ 5 (in mg/dL). It is simple, which is why many labs still print it, but it reads too low when triglycerides are high or LDL is low, and it is not valid at triglycerides of 400 mg/dL or more.

Sampson-NIH (2020): LDL = total ÷ 0.948 − HDL ÷ 0.971 − (TG ÷ 8.56 + TG × non-HDL ÷ 2,140 − TG² ÷ 16,100) − 9.44. It was built against the reference ultracentrifuge method and stays accurate up to triglycerides of 800 mg/dL. The 2026 ACC/AHA multisociety dyslipidaemia guideline (March 2026) prefers Sampson-NIH or Martin-Hopkins over Friedewald, so Sampson-NIH is the default here. Martin-Hopkins needs a 180-cell table of factors and is not included.

To convert, divide mg/dL by 38.67 for cholesterol and by 88.57 for triglycerides to get mmol/L.

Bands and targets

Most Indian lab reports print the NCEP ATP III (2002) bands: optimal below 100 mg/dL, near optimal 100–129, borderline high 130–159, high 160–189 and very high 190 or more.

Targets depend on your risk. The Lipid Association of India, Consensus Statement IV (2023 update, published in the Journal of Clinical Lipidology, 2024) looks at lifetime risk, because heart disease strikes Indians about a decade earlier than people in the West. It sets below 50 mg/dL for people who have had a heart attack, stroke or stent and 30 or less for extreme risk; this tool uses below 100 for people without heart disease and below 70 for diabetes or several risk factors. The ESC/EAS (2019) targets are below 116, 100, 70 and 55 mg/dL for low, moderate, high and very high risk. Checked as of October 2026; your doctor sets your own target.

Non-HDL and triglycerides

Non-HDL cholesterol (total minus HDL) is every kind of cholesterol that can clog arteries, and it needs no formula, so doctors use it when triglycerides are high. A useful rule of thumb: the non-HDL goal is the LDL goal plus 30 mg/dL. The TG/HDL ratio (in mg/dL) above about 3.5 often goes with insulin resistance, common in South Asians.

Rajesh, a shop owner in Salem

Rajesh, 47, gets a lipid profile at a lab near the bus stand: total 225, HDL 38, triglycerides 300 mg/dL. The lab prints a Friedewald LDL of 127, near optimal. The tool gives 133 by Sampson-NIH: high triglycerides make Friedewald read low, so his LDL is really borderline high. His non-HDL is 187. He has diabetes, so his LAI target is below 70. He takes both numbers to his doctor, who plans diet, walking and treatment with him. Six months later he adds the old report under Earlier reports and watches the line come down.

Common mistakes

• Mixing units: typing mmol/L values into mg/dL boxes (a total of 5.2 is mmol/L). Pick the units first.
• Comparing two labs’ LDL directly: one may use Friedewald, another Sampson-NIH or a direct test.
• A non-fasting test with very high triglycerides: if triglycerides are over 400, repeat after a 10–12 hour fast or ask for a direct LDL.
• Judging by bands alone: with diabetes or past heart disease, “near optimal” can still be far above your target.
• Changing medicines on your own: talk to your doctor first.