Lab unit converter (mg/dL ↔ SI units)

The same blood test can be expressed in two systems of units. mg/dL (milligrams per deciliter) is used in the United States and a few other countries. The International System of Units (SI) expresses these tests in mmol/L (millimoles per liter), and in µmol/L (micromoles per liter) for creatinine and uric acid; these units are used across most of Europe and in the scientific literature. In essence, both describe the same reality; only the way of expressing it differs.

The conversion is done by multiplying or dividing the value by a factor that depends on the substance being measured, because each has a different molecular mass. For example, blood glucose in mg/dL is divided by 18 to get mmol/L, and cholesterol is divided by 38.67 [1]. The calculator above automatically chooses the correct factor for the selected test and converts both ways.

The usual factors are:

• blood glucose — divide by 18;
• total cholesterol, HDL and LDL — divide by 38.67;
• triglycerides — divide by 88.57;
• creatinine — multiply by 88.42, giving a result in µmol/L;
• uric acid — multiply by 59.48, also in µmol/L.

These values are rounded by convention, and some sources round them slightly differently. For the reverse conversion, from SI units to mg/dL, do the opposite: multiply by 18 for blood glucose, by 38.67 for cholesterol and by 88.57 for triglycerides; for creatinine and uric acid, divide by 88.42 and 59.48, respectively.

They are useful when you receive a lab report in a system of units you are not used to, when you compare results from different countries, when you follow a foreign guideline or scientific article, or when you set up a device (a glucose meter or sensor) configured for a different unit. The conversion lets you understand the value quickly, without manual calculations. The passage between HbA1c and estimated average glucose is a conversion of another kind, and it has a tool of its own, the HbA1c calculator.