Why Do US and Canadian Cholesterol Reports Use Different Units?

If you have ever compared a US lab report against a Canadian or British one, you may have noticed the cholesterol numbers look wildly different — a total cholesterol of 193 on one report and 5.0 on another can describe the same blood. The tests agree; the units differ.

Two systems for the same measurement

US laboratories report cholesterol in milligrams per deciliter (mg/dL) — a mass of cholesterol per volume of blood. Most of the rest of the world, including Canada, uses millimoles per liter (mmol/L) — a count of molecules per volume, part of the international SI system of units. Neither is more accurate; they are two rulers for the same distance, the way miles and kilometers both measure a road.

This matters in practice because heart-health information crosses borders constantly. Materials from the Heart and Stroke Foundation of Canada quote values in mmol/L; materials from the American Heart Association use mg/dL. A reader who doesn't know the units differ can badly misread one or the other.

Converting between them

For cholesterol — total, LDL, or HDL — one mmol/L equals roughly 38.7 mg/dL. So to move between systems:

• mmol/L → mg/dL: multiply by about 38.7
• mg/dL → mmol/L: divide by about 38.7

Our cholesterol unit converter on the home page does this arithmetic for you.

The factor comes from chemistry, not convention: a mole is a fixed count of molecules, so converting a molecule-count unit to a mass unit depends on the molecular weight of the substance being measured. That leads to an important caution:

• The cholesterol factor applies only to cholesterol. Total, LDL, and HDL cholesterol all measure the same molecule, so one factor serves all three.
• Triglycerides use a different factor, because triglycerides are different, heavier molecules.
• Blood glucose uses yet another factor. A glucose value in mmol/L cannot be converted with the cholesterol number.

If a report line item isn't cholesterol, don't use the cholesterol factor on it.

Reading a lipid panel's vocabulary

Whichever units your report uses, the same terms appear:

• Total cholesterol — all cholesterol carried in your blood, combined.
• LDL (low-density lipoprotein) — often labeled the "bad" kind in patient materials because of its role in artery-narrowing plaque, a process described in the NHLBI's coronary heart disease overview.
• HDL (high-density lipoprotein) — often labeled the "good" kind.
• Triglycerides — a type of fat in the blood, reported alongside cholesterol but chemically distinct.
• Non-HDL cholesterol — total cholesterol minus HDL, a derived number some reports include.

What this page deliberately doesn't do

You'll notice no target numbers here. What counts as a desirable value depends on your overall situation — age, history, other conditions, medications — and that judgment belongs to your clinician, not to a unit-conversion page. The honest use of this page is narrower: when you read international material or compare reports across borders, make sure you're comparing mmol/L to mmol/L or mg/dL to mg/dL. The MedlinePlus heart diseases hub is a good starting point for vetted patient-level information once your units are straight.