Blood Sugar Converter
Convert blood sugar levels between mg/dL and mmol/L.
Includes reference ranges for fasting, post-meal, and A1C equivalents.
Blood sugar level conversion allows switching between the two global measurement systems: mg/dL (milligrams per deciliter), used in the United States, and mmol/L (millimoles per liter), used in most other countries.
Conversion formulas: mmol/L → mg/dL: mg/dL = mmol/L × 18.018 mg/dL → mmol/L: mmol/L = mg/dL ÷ 18.018
The factor 18.018 comes from glucose’s molecular weight (180.18 g/mol) divided by 10.
Clinical reference ranges (American Diabetes Association guidelines):
| Category | mg/dL | mmol/L |
|---|---|---|
| Fasting — Normal | 70–99 | 3.9–5.5 |
| Fasting — Prediabetes | 100–125 | 5.6–6.9 |
| Fasting — Diabetes | 126+ | 7.0+ |
| 2-hr post-meal — Normal | Under 140 | Under 7.8 |
| 2-hr post-meal — Prediabetes | 140–199 | 7.8–11.0 |
| 2-hr post-meal — Diabetes | 200+ | 11.1+ |
| Hypoglycemia (low) | Below 70 | Below 3.9 |
| Severe hypoglycemia | Below 54 | Below 3.0 |
| Target range (diabetics) | 80–130 | 4.4–7.2 |
HbA1c to average blood glucose: Estimated Average Glucose (mg/dL) = (HbA1c × 28.7) − 46.7 Estimated Average Glucose (mmol/L) = (HbA1c × 1.59) − 2.59
Worked example: A blood test in Germany shows 8.3 mmol/L fasting. mg/dL = 8.3 × 18.018 = 149.5 mg/dL Interpretation: This is above the diabetic threshold of 126 mg/dL fasting — requires medical evaluation.
Blood sugar monitoring is essential for people with type 1, type 2, and gestational diabetes, as well as those in the prediabetes range. Consistent tracking informs diet, medication, and lifestyle adjustments.