Blood test converter
Choose the test and direction, enter the value: convert between mg/dL and mmol/L.
What it's for
Lab reports use different units by country: often mg/dL in some, mmol/L in others. This converts the main blood values between the two units.
Important
It's a simple unit converter, not an interpretation of results. To understand your values always talk to your doctor.
Why two units for the same thing
The two units answer two different questions. mg/dL says how many milligrams of a substance there are in a decilitre of blood: it's a measure of weight, convenient and concrete. mmol/L says how many molecules there are: it's a measure of amount of substance, and it has a precise advantage, because in chemistry it's molecules that react, not grams. It's why the international system uses millimoles and most of the world's laboratories have moved there.
The consequence is that the conversion factor changes from test to test: it depends on the molecule's weight. For glucose you divide by 18, for cholesterol by 38.67, for creatinine you multiply by 88.4. There's no single number, which is why a mental conversion isn't something to improvise.
The values most often confused
A glucose of 100 in mg/dL is 5.6 in mmol/L: two very distant numbers saying the same thing, and it's the commonest mistake when reading a foreign report or a scientific article. Cholesterol goes from 200 mg/dL to 5.2 mmol/L. Glycated haemoglobin has an extra problem: two scales exist (as a percentage and in mmol/mol) and neither is strictly a unit conversion of the other, so it should only be compared with the scale on the report.
Converting isn't interpreting
This page changes the unit, it doesn't say whether the value is normal. And the reference ranges belong to the laboratory that ran the analysis, they aren't universal: they change with the method used, with age, with sex, with pregnancy, and they're printed next to the result for precisely that reason. Comparing your own number with a table found online, instead of with the range written on your own report, is the quickest way to be frightened or reassured for nothing.
Nearby tools
For blood pressure, which has a single scale but plenty of measurement pitfalls, there is Blood pressure values. For weight against height BMI calculator and Waist-to-height ratio, and for units in general Weight converter.