Why do different countries use different units?
US adopted mg/dL historically; most other countries use SI units (mmol/L).
Health Fitness
Blood Sugar Converter Calculator
Calculate blood sugar converter with your details.
Personalized estimate
Use realistic inputs for the most useful results.
What this calculator does
Blood glucose is measured in mg/dL (US) or mmol/L (international). Both describe the same measurement using different scales based on glucose's molecular weight.
How it works
Conversion uses a fixed ratio: one mmol/L = 18 mg/dL. Multiply mmol/L by 18 for mg/dL, or divide mg/dL by 18 for mmol/L.
Formula
mg/dL to mmol/L: ÷ 18. mmol/L to mg/dL: × 18. Example: 100 mg/dL ÷ 18 = 5.6 mmol/L.
Tips for using this calculator
- Know which unit your glucose monitor uses
- Fasting normal: 70-100 mg/dL or 3.9-5.6 mmol/L
- Use factor of 18 for quick mental math
- Trends show same direction in both units
- Confirm conversions with your doctor
Frequently asked questions
Is 18 or 18.0182 better?
18 is sufficient for practical use with negligible 0.1% error.
What are normal glucose ranges?
Fasting: 72-108 mg/dL (4.0-6.0 mmol/L). Diabetes: ≥126 mg/dL (≥7.0 mmol/L).