What is the conversion factor for blood sugar units?

The conversion factor is 18.018 (based on the molar mass of glucose, 180.18 g/mol). To convert mg/dL to mmol/L, divide by 18.018. To convert mmol/L to mg/dL, multiply by 18.018. For example, 100 mg/dL ÷ 18.018 = 5.55 mmol/L.

Which countries use mg/dL vs mmol/L for blood sugar?

The United States uses mg/dL (milligrams per deciliter). Most other countries — including the UK, Canada, Australia, and EU nations — use mmol/L (millimoles per liter). If you travel internationally or follow guidelines from a different country, you may need to convert your blood glucose readings.

What is a normal fasting blood sugar level?

A normal fasting blood sugar level is 70–100 mg/dL (3.9–5.6 mmol/L), according to the American Diabetes Association. Prediabetes is diagnosed when fasting levels are 100–125 mg/dL (5.6–6.9 mmol/L). Diabetes is indicated by fasting levels of 126 mg/dL (7.0 mmol/L) or higher on two separate tests.

Blood Sugar Converter — mg/dL ↔ mmol/L

By KAMP Inc. / UnitOwl · Last reviewed: April 3, 2026

Instantly convert blood glucose levels between mg/dL (used in the US) and mmol/L (used in the UK, Canada, Australia, and most of Europe). Enter any value to see the equivalent, plus your reading's clinical range.

Medical Disclaimer: This converter is for informational purposes only. Blood glucose targets vary by individual, condition, and medication. Always consult your healthcare provider for personalized guidance.

mg/dL

mmol/L

5.55

Prediabetes Range

Formula: mg/dL ÷ 18.018 = mmol/L

mg/dL → mmol/L → mmol/L → mg/dL →

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Blood Sugar Units: mg/dL vs mmol/L

Blood glucose (blood sugar) is the concentration of glucose in your blood. Two different measurement systems are used worldwide, creating the need for conversion when reading international guidelines, comparing glucometers, or traveling abroad.

mg/dL (milligrams per deciliter) is used in the United States and a small number of other countries. It measures the mass of glucose in 100 milliliters of blood. A reading of 100 mg/dL means there are 100 milligrams of glucose per deciliter of blood.

mmol/L (millimoles per liter) is the standard in the UK, Canada, Australia, Germany, France, and most of the world. It measures the number of glucose molecules per liter of blood, using the International System of Units (SI). A reading of 5.5 mmol/L is approximately equal to 99 mg/dL.

The conversion factor is 18.018, derived from the molar mass of glucose (C₆H₁₂O₆ = 180.18 g/mol ÷ 10). To convert mg/dL to mmol/L, divide by 18.018. To convert mmol/L to mg/dL, multiply by 18.018. Many people use the approximation of 18 for quick mental math.

Clinical Reference Ranges

Status	mg/dL	mmol/L
Normal (fasting)	70 – 100	3.9 – 5.6
Prediabetes (fasting)	100 – 125	5.6 – 6.9
Diabetes (fasting)	≥ 126	≥ 7.0
Normal (post-meal, 2hr)	< 140	< 7.8
Prediabetes (post-meal)	140 – 199	7.8 – 11.0
Diabetes (post-meal)	≥ 200	≥ 11.1
Hypoglycemia	< 70	< 3.9
Severe hypoglycemia	< 54	< 3.0

Sources: American Diabetes Association (2024), WHO Diabetes Guidelines

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Common Blood Sugar Conversions

These are frequently needed conversions for people managing diabetes, following international guidelines, or comparing readings from different glucometers.

mg/dL → mmol/L

54 mg/dL 3.0 mmol/L

70 mg/dL 3.9 mmol/L

100 mg/dL 5.6 mmol/L

126 mg/dL 7.0 mmol/L

140 mg/dL 7.8 mmol/L

180 mg/dL 10.0 mmol/L

200 mg/dL 11.1 mmol/L

mmol/L → mg/dL

3.0 mmol/L 54 mg/dL

3.9 mmol/L 70 mg/dL

5.6 mmol/L 101 mg/dL

7.0 mmol/L 126 mg/dL

7.8 mmol/L 141 mg/dL

10.0 mmol/L 180 mg/dL

11.1 mmol/L 200 mg/dL

Frequently Asked Questions

Is 7.0 mmol/L the same as 126 mg/dL?

Yes. 7.0 mmol/L × 18.018 = 126.1 mg/dL, which rounds to the diagnostic threshold of 126 mg/dL used by the ADA for a diabetes diagnosis based on fasting glucose. This is one of the most clinically important equivalences to know.

Why does my US meter show a different number than a UK guide?

US glucometers display results in mg/dL, while UK and European guidelines are written in mmol/L. A reading of 5.5 on a UK chart equals about 99 mg/dL on a US meter. Always check which unit system a guideline uses before comparing your readings.

Can I use 18 instead of 18.018 for quick conversions?

Yes, dividing or multiplying by 18 is a common mental shortcut and accurate enough for everyday reference. The small difference (0.1%) is clinically insignificant. For example, 5.6 mmol/L × 18 = 100.8 mg/dL vs. × 18.018 = 101.0 mg/dL — essentially the same reading.

What is a safe blood sugar level before exercise?

The ADA recommends checking blood sugar before exercise. Generally, levels below 90 mg/dL (5.0 mmol/L) may require a carbohydrate snack before starting. Levels above 250 mg/dL (13.9 mmol/L) with ketones present may indicate you should delay exercise. Always follow your healthcare provider's specific guidance.

What blood sugar level is dangerous?

Hypoglycemia (low blood sugar) below 70 mg/dL (3.9 mmol/L) requires treatment; below 54 mg/dL (3.0 mmol/L) is considered severe. Hyperglycemia above 300 mg/dL (16.7 mmol/L) can be dangerous, and diabetic ketoacidosis (DKA) can develop at high sustained levels. Seek immediate medical attention for readings outside safe ranges or if symptoms are present.

Sources & References

American Diabetes Association — Standards of Medical Care in Diabetes (2024) — Diagnostic criteria and blood glucose thresholds.
World Health Organization — Classification and Diagnosis of Diabetes — WHO global diagnostic thresholds in mmol/L.
Diabetes UK — Blood Sugar Level Ranges — UK reference ranges in mmol/L.
CDC — Diabetes Testing and Diagnosis — US reference ranges in mg/dL.

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