Blood Sugar mmol/L to mg/dL Converter

If you've ever read a blood glucose of 7.2 and wondered whether that's good or dangerously high — the answer depends entirely on whether it's 7.2 mmol/L (which is normal post-meal in many guidelines) or 7.2 mg/dL (which would be critically low and a medical emergency). The two scales look completely different, sound different, and are used by different countries — but they measure exactly the same thing. The blood sugar converter handles the conversion instantly in both directions.

The Conversion Formula — and Why It's Not a Round Number

The conversion factor is 18.016, based on the molecular weight of glucose (180.16 g/mol):

mg/dL = mmol/L × 18.016

mmol/L = mg/dL ÷ 18.016

In practice, 18 is used as the approximation in most clinical settings, which introduces an error of less than 0.1%. Key reference values in both units:

• Normal fasting glucose: 70–99 mg/dL = 3.9–5.5 mmol/L
• Prediabetes fasting: 100–125 mg/dL = 5.6–6.9 mmol/L
• Diabetes diagnosis threshold: ≥126 mg/dL = ≥7.0 mmol/L
• 2-hour post-meal (normal): below 140 mg/dL = below 7.8 mmol/L
• Hypoglycemia threshold: below 70 mg/dL = below 3.9 mmol/L
• Severe hypoglycemia: below 54 mg/dL = below 3.0 mmol/L

Use this online calculator for any glucose value conversion. The HbA1c converter handles the related long-term glucose marker conversion.

Which Countries Use Which Unit?

Understanding which system your meter, prescription, or guidelines use prevents dangerous errors:

• mg/dL: United States, Japan, South Korea, China, most of Latin America and the Middle East
• mmol/L: United Kingdom, Canada, Australia, New Zealand, most of Europe, and Africa
• Transition countries: Some countries use both; medical literature increasingly reports in mmol/L for international consistency

If you're traveling and using a different glucometer, or reading a research paper from a different country, or your provider just moved from one country to another, always check which unit system applies before interpreting or acting on a value. A blood glucose of "4" is fine in mmol/L (72 mg/dL — low-normal), but a "4" in mg/dL would be critically low and would require immediate intervention.

Continuous Glucose Monitors (CGMs) and Unit Settings

Modern CGMs like the Dexcom G7, FreeStyle Libre, and Medtronic Guardian can usually be configured to display in either mmol/L or mg/dL. If you've recently changed your device settings or switched devices, verify which unit is active before making any dosing decisions. CGM manufacturers typically set the default based on the country of sale, but user settings can override this — and the resulting confusion when a device suddenly shows "4.2" instead of "76" has led to avoidable hypoglycemia events. Always check your device's unit setting when it's been reset, updated, or replaced. For clinical interpretation, always consult your healthcare provider.