Last updated: 2026-06-22

Triglyceride to HDL Ratio

The triglyceride-to-HDL ratio divides the fasting triglyceride level by the HDL cholesterol level, both read from a standard lipid panel. It is studied as a marker of insulin resistance and of small, dense LDL particles, and it is attractive precisely because it needs nothing beyond two numbers that already appear on most cholesterol reports. A common reading is that a ratio below 2 is favourable, 2 to 3 is borderline, and above 3 is unfavourable.

The formula

Both quantities are entered in milligrams per decilitre. The result is dimensionless: it is the number of units of triglyceride present for each unit of HDL cholesterol. Because triglycerides usually run several times higher than HDL, the ratio is typically a small single-digit number.

Worked example

Consider a lipid panel reporting triglycerides of 100 mg/dL and HDL cholesterol of 50 mg/dL:

A value of two sits at the boundary between the favourable and borderline bands, consistent with moderate triglycerides relative to a typical HDL level.

Why the unit matters here

This is the detail that separates the triglyceride-to-HDL ratio from the more familiar total-cholesterol-to-HDL ratio. The total-cholesterol ratio compares two quantities of the same kind, so converting both from mg/dL to mmol/L uses the same factor and the ratio is unchanged. Triglycerides and HDL cholesterol are different molecules with different molar masses, so they convert by different factors: triglycerides are divided by 88.57 and HDL by 38.67. A ratio computed straight from mmol/L values therefore comes out about 2.2 times smaller than the same panel expressed in mg/dL. The thresholds quoted here were derived in mg/dL, so a reading in mmol/L should be converted before it is entered; the mg/dL boundary near 1.9 corresponds to roughly 0.87 in mmol/L.

Interpreting the number

The ratio is read as a marker of metabolic health rather than as a target in its own right. A high triglyceride level combined with a low HDL level is part of the pattern associated with insulin resistance, and the ratio rises as that pattern develops. Research has also linked higher ratios to a greater proportion of small, dense LDL particles, which are harder to clear and more readily oxidised than larger LDL. The bands shown alongside the result follow the common below-two, two-to-three, above-three scheme, though sources differ on the exact cut-offs and on the populations they best apply to. For one person, the direction of travel across several panels usually says more than a single reading.

Limits

The ratio is a screening figure built from two numbers and inherits their variability: triglycerides in particular swing with recent meals, alcohol, and the length of the fast before the draw. It does not replace the full lipid panel or a clinical assessment, and it performs differently across ancestries. It is best read alongside other measures such as the Cholesterol Ratio Calculator and, for body composition, the BMI Calculator. Any decision about treatment should rest on a professional review of the complete panel rather than on a single ratio.