Triglyceride-to-HDL Ratio Calculator

Triglycerides and HDL cholesterol are already sitting on most routine lipid panels, so this ratio costs nothing extra to calculate once you have those two numbers. Researchers at Stanford first identified it as a useful, low-cost stand-in for insulin resistance testing, since the gold-standard tests, such as a clamp study, take hours in a research lab, and even a fasting insulin test isn't part of most routine care¹.

What This Calculator Measures

This is a screening signal built from two numbers you likely already have, not a direct measurement of insulin resistance. It flags whether your lipid pattern looks like the pattern typically seen in insulin-resistant people, which is a different thing from testing insulin resistance directly.

The Formula

Ratio = Triglycerides ÷ HDL-C (same unit for both)

Triglycerides and HDL cholesterol use different mg/dL-to-mmol/L conversion factors (triglycerides divide by 88.57, HDL-C divides by 38.67, since the two molecules have very different molecular weights). Because the factors differ, the ratio itself changes depending on which unit system you calculate it in, a ratio worked out entirely in mmol/L is roughly 0.44 times the same blood values' ratio worked out in mg/dL, even though nothing about the actual blood values changed. The commonly cited cutoff of 3.5 applies specifically to the mg/dL version of the ratio, and needs rescaling to roughly 1.5 for anyone working in mmol/L, which is most of the world outside the United States.

How This Calculator Computes Your Result

Enter your triglycerides and HDL-C, choosing mg/dL or mmol/L for each independently, since lab reports don't always use the same units for both. We convert both values to mg/dL internally using their respective conversion factors, calculate the ratio in mg/dL terms, and interpret it against the mg/dL-based reference bands below, regardless of which units you originally entered.

What Your Result Means

The 3.5 cutoff comes from a 2005 Stanford study, where a ratio of 3.5 or higher picked out insulin-resistant people⁵. The first Stanford study, in overweight adults, found 3.0 worked best¹. The 2.0 line for Optimal is a common rule of thumb, not a tested cutoff. A larger 2024 systematic review pooling 32 studies and roughly 49,800 participants found the average cutoff that best distinguished insulin-resistant individuals was somewhat lower and sex-specific, about 2.53 for women and 2.8 for men⁴. Both frameworks are in active use; treat the band above as a general guide rather than an exact line, and discuss where you fall with a healthcare provider.

Why This Ratio Doesn't Work the Same for Everyone

The relationship between this ratio and insulin resistance was first established in a predominantly white study population¹, and it does not hold consistently across every racial and ethnic group. One study of Black American adults found that neither triglyceride levels nor the TG/HDL-C ratio distinguished insulin-resistant individuals at all in that sample².

A separate, larger analysis found the ratio did track fasting insulin across white, Black, and Mexican American adults. It worked with a single cutoff of 3.5, and slightly better with a different cutoff for each group, about 3.0 for white and Mexican American adults versus about 2.0 for Black adults³. The 2024 systematic review reached a similar conclusion from a different angle, finding the ratio predicts insulin resistance more accurately in Caucasians, Asians, and Hispanics than in African Americans, and more accurately in men than in women⁴.

Because the research doesn't agree on the size, or even always the direction, of an appropriate adjustment, this calculator does not attempt to encode a race- or ethnicity-specific cutoff into the result. If you are Black or African American, an elevated result here should be treated with particular caution, and a direct measure such as HOMA-IR or a fasting insulin test, discussed with your provider, is a more reliable next step than this ratio alone.

This Is a Screening Marker, Not a Diagnosis

A high ratio suggests it's worth investigating further, it doesn't confirm insulin resistance on its own. HOMA-IR (calculated from fasting glucose and fasting insulin) or a clinical evaluation is what actually establishes a diagnosis.