Blood Sugar Converter

mg/dL	100 mg/dL

Last updated: 2026-07-02

Blood sugar units

Blood glucose concentration is reported in two different unit systems around the world. Which one you see depends mainly on where you live and which lab or device produced the reading.

mg/dL (milligrams per deciliter) is a mass concentration: the number of milligrams of glucose in one deciliter (100 mL) of blood. It is the conventional unit in the United States, Japan, and several other countries.

mmol/L (millimoles per liter) is a molar concentration: the number of millimoles of glucose molecules in one liter of blood. It is the SI unit and is used across most of Europe, Australia, Canada, and in international scientific literature.

Both units describe the exact same physical quantity — how much glucose is dissolved in the blood — so any reading can be expressed either way.

The conversion factor

The two units are linked by the molar mass of glucose (C₆H₁₂O₆), which is about 180.156 g/mol. Accounting for the deciliter-versus-liter volume difference gives a single constant:

1 mmol/L = 18.0156 mg/dL

From this, the two directions follow:

mg/dL to mmol/L: divide by 18.0156
mmol/L to mg/dL: multiply by 18.0156

Worked example

Suppose a glucose meter shows 100 mg/dL and you want the SI value.

Divide by the conversion factor:

100 ÷ 18.0156 = 5.55 mmol/L

To go the other way, take a reading of 7 mmol/L and multiply:

7 × 18.0156 = 126.1 mg/dL

Quick reference table

mg/dL	mmol/L
70	3.89
90	5.00
100	5.55
126	6.99
140	7.77
180	9.99
200	11.10

Usage

Enter a value in either field. The other unit updates automatically. Type 100 in the mg/dL field to see 5.55 mmol/L, or type 7 in the mmol/L field to see 126.1 mg/dL.

Frequently Asked Questions (FAQ)

How do I convert mg/dL to mmol/L?

Divide the mg/dL value by 18.0156. For example, 100 mg/dL ÷ 18.0156 ≈ 5.55 mmol/L. The divisor comes from the molar mass of glucose (180.156 g/mol), which links mass concentration (mg/dL) to molar concentration (mmol/L).

How do I convert mmol/L to mg/dL?

Multiply the mmol/L value by 18.0156. For example, 5.5 mmol/L × 18.0156 ≈ 99.1 mg/dL. This is the reverse of the mg/dL to mmol/L conversion.

Why are there two different units for blood sugar?

mg/dL is a mass-based unit (milligrams of glucose per deciliter of blood), while mmol/L is a molar unit (millimoles of glucose per liter). The United States and a few other countries report glucose in mg/dL, whereas most of the world and international scientific literature use the SI unit mmol/L. Both describe the same physical quantity; only the unit differs.

Where does the factor 18.0156 come from?

It is the molar mass of glucose (C₆H₁₂O₆), about 180.156 g/mol. Because 1 mmol/L equals 1 millimole of glucose per liter, converting to a mass concentration multiplies by the molar mass and adjusts for the deciliter versus liter volume, giving 1 mmol/L = 18.0156 mg/dL.

Disclaimer

This tool performs a unit conversion only and is for general informational purposes. It does not interpret results, define normal or target ranges, or provide medical advice. Consult a qualified healthcare professional for guidance on blood glucose values.

Blood Sugar Converter

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Blood Sugar Converter

Conventional Units (mg/dL)

SI Units (mmol/L)

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