Laboratory & Medical Units

About the Laboratory & Medical Units

Laboratory units are not interchangeable because the denominator differs: mass per volume (mg/dL), amount of substance per volume (mmol/L, µmol/L) and mass per volume in SI (g/L). Converting glucose from mg/dL to mmol/L divides by 18.02; cholesterol divides by 38.67; creatinine multiplies by 88.4 to reach µmol/L.

This converter covers the common analytes and reports the result in every unit used for that test. Reference ranges are included as orientation only. They vary by laboratory, method, age, sex and pregnancy, and a result should always be interpreted against the range printed on the report.

How the calculation works

• Glucose: mg/dL ÷ 18.0182 = mmol/L.
• Cholesterol: mg/dL ÷ 38.67 = mmol/L.
• Creatinine: mg/dL × 88.4 = µmol/L.
• Bilirubin: mg/dL × 17.1 = µmol/L.
• Calcium: mg/dL ÷ 4.008 = mmol/L.

Reference values

Worked example: three common results

A glucose result of 90 mg/dL is 90 ÷ 18.0182 = 5.0 mmol/L. A cholesterol of 200 mg/dL is 5.17 mmol/L. A creatinine of 1.0 mg/dL is 88.4 µmol/L. These are unit conversions only; the reference range printed on your report is the one that matters.

Laboratories choose units by convention and discipline. SI units are standard in many European and international laboratories, while mg/dL remains common in the US. The underlying result is the same; only the unit and the reference interval change. Never compare a number across units without converting it first.

Frequently asked questions

Sources and standards

Laboratory results are not interchangeable across countries: glucose may be reported in mg/dL or mmol/L, and the conversion depends on molar mass. Values here use IUPAC molar masses from the NIST CODATA compilation, and the page warns that reference ranges are assay-specific.

• NIST — CODATA recommended values of the fundamental constants
• NIST Special Publication 811 — Guide for the Use of the SI

Related tools