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

Health Updated 14 Jun 2026

Convert blood glucose readings between mg/dL and mmol/L instantly. Choose a direction, enter your value, and this calculator returns the equivalent in the other unit using the standard factor of 18.

Formula

mmol/L = mg/dL ÷ 18 mg/dL = mmol/L × 18
  • To convert mg/dL to mmol/L, divide by 18 (more precisely 18.0182).
  • To convert mmol/L to mg/dL, multiply by 18.
  • The factor comes from the molar mass of glucose (180.16 g/mol) and the unit definitions.
  • mg/dL is used mainly in the US, while mmol/L is standard across Canada, the UK, and most of Europe.
  • The two units describe the same blood sugar — only the scale differs.

100 mg/dL to mmol/L

Inputs
  • Convert: mgToMmol
  • Blood glucose value: 100

100 ÷ 18 ≈ 5.6 mmol/L — a normal fasting glucose level.

Frequently asked questions

How do I convert mg/dL to mmol/L?
Divide the mg/dL value by 18. For example, 90 mg/dL ÷ 18 = 5.0 mmol/L.
How do I convert mmol/L to mg/dL?
Multiply the mmol/L value by 18. For example, 7.0 mmol/L × 18 = 126 mg/dL.
Why is the factor 18?
It derives from the molar mass of glucose (about 180 g/mol). Dividing or multiplying by 18 converts between the mass-based and molar-based units.
Which unit does my country use?
The US generally uses mg/dL; Canada, the UK, Australia, and most of Europe use mmol/L. Both measure the same thing.
Is the conversion exact?
18 is a convenient rounding; the precise factor is 18.0182. For everyday readings, 18 is accurate enough.

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