Blood Sugar Conversion Calculator
Convert blood sugar levels between mg/dL and mmol/L.
Includes reference ranges for fasting, post-meal, and A1C equivalents.
Blood sugar unit conversion switches between milligrams per deciliter (mg/dL), used in the United States, and millimoles per liter (mmol/L), used in most other countries. The conversion factor is a fixed constant.
Conversion Formulas:
mmol/L = mg/dL / 18.02
mg/dL = mmol/L × 18.02
The factor 18.02 represents the molar mass of glucose (180.2 g/mol) divided by 10. Because glucose is a single compound with a known molecular weight, this conversion is exact — not an approximation.
Worked example: US reading: 126 mg/dL (fasting) International: 126 / 18.02 = 6.99 mmol/L → 7.0 mmol/L
International reading: 5.5 mmol/L US equivalent: 5.5 × 18.02 = 99.1 → 99 mg/dL
Clinical reference ranges (fasting blood glucose):
| Category | mg/dL | mmol/L |
|---|---|---|
| Normal | 70–99 | 3.9–5.5 |
| Prediabetes | 100–125 | 5.6–6.9 |
| Diabetes | 126+ | 7.0+ |
| Hypoglycemia | Below 70 | Below 3.9 |
| Severe hypoglycemia | Below 54 | Below 3.0 |
HbA1c to average glucose conversion:
Estimated Average Glucose (mg/dL) = (HbA1c × 28.7) − 46.7
Example: HbA1c of 7.0% → (7.0 × 28.7) − 46.7 = 200.9 − 46.7 = 154 mg/dL average
Practical context:
- Post-meal glucose normally peaks 60–90 minutes after eating and returns to baseline within 2 hours
- Target post-meal peak for non-diabetics: below 140 mg/dL (7.8 mmol/L)
- CGM devices (Dexterity, Libre) display readings in the units set by the user’s device region
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
SuperGlobalCalculator is independently built and maintained. See how we build and verify our calculators.