Blood Sugar Converter (mg/dL to mmol/L)

How it works

mmol/L = mg/dL ÷ 18.016 · mg/dL = mmol/L × 18.016 (glucose molar mass 180.16 g/mol; 1 mmol/L = 18.016 mg/dL, usually rounded to 18)

Blood glucose is reported in milligrams per decilitre in the United States and a few other countries, and in millimoles per litre in most of the world. Because glucose weighs 180.16 g per mole, 1 mmol/L equals 18.016 mg/dL, so you divide by 18 to go to mmol/L and multiply by 18 to go to mg/dL. The categories use the American Diabetes Association diagnostic cut-offs (fasting 100 and 126 mg/dL, 2-hour OGTT 140 and 200 mg/dL) and the hypoglycemia levels (below 70 and below 54 mg/dL).

Worked example

A fasting reading of 100 mg/dL: 100 ÷ 18.016 = 5.55, shown as 5.6 mmol/L. Under the ADA cut-offs a fasting value of 100–125 mg/dL (5.6–6.9 mmol/L) is the prediabetes range (impaired fasting glucose), so this reading sits right at its lower edge; below 100 mg/dL would be normal.

Sources: American Diabetes Association. Standards of Care in Diabetes — Diagnosis and Classification · Diabetes UK: blood sugar conversion (mmol/L and mg/dL)

Frequently asked questions