Cholesterol Ratio Calculator

Friedewald estimates LDL from a standard lipid panel as LDL = Total cholesterol minus HDL minus triglycerides divided by 5 (all in mg/dL). The triglycerides/5 term approximates VLDL cholesterol. The formula assumes a fasting sample and is only valid when triglycerides are under 400 mg/dL. At 400 mg/dL or higher, this calculator leaves LDL and the LDL band unclassified unless you enter a direct LDL value. Ask your lab for a direct LDL measurement or an alternative equation like Martin-Hopkins or Sampson.

This calculator uses under 3.5, 3.5 to under 5, and 5 or higher as descriptive ratio bands. They are not current AHA treatment thresholds. A cholesterol ratio can provide context, but current prevention decisions emphasize LDL cholesterol, non-HDL cholesterol, triglycerides, and overall risk assessed with PREVENT. Do not use the ratio alone to decide whether treatment is needed.

The calculator uses legacy NCEP metabolic-syndrome cutoffs of under 40 mg/dL for men and under 50 mg/dL for women. HDL is one part of a lipid panel, but a high value does not cancel other risk factors and is not a treatment target by itself. Current decisions use the full lipid profile and overall cardiovascular risk rather than treating 60 mg/dL as a universal protective threshold.

AIP is log10 of the triglyceride to HDL ratio measured in mmol/L. Values above 0.21 are linked to higher cardiovascular risk, partly because the ratio correlates with the small dense LDL particles that traditional lipid panels miss. AIP is an emerging marker introduced by Dobiasova in 2004; it is useful alongside standard ratios but is not yet in primary prevention guidelines.

The displayed LDL bands come from the older NCEP ATP III categories: under 100, 100 to 129, 130 to 159, 160 to 189, and 190 mg/dL or higher. They are descriptive legacy bands, not the current 2026 treatment algorithm. Current AHA and ACC guidance combines LDL and non-HDL cholesterol with PREVENT risk, clinical conditions, risk enhancers, and sometimes coronary artery calcium. Review a treatment target with a clinician.