Blood Sugar Converter
mg/dL to mmol/L

A free blood sugar converter and calculator. Instantly convert mmol/L to mg/dL, mg/dL to mmol/L, and estimate your HbA1c. The conversion factor is 18: multiply mmol/L by 18 to get mg/dL, or divide mg/dL by 18 to get mmol/L.

mg/dL to mmol/L Calculator

Used by US, Japan

Used by UK, Australia, Canada, Singapore, most European countries

~3 month average blood sugar

Type a value in any field and the other two update automatically. The mg/dL and mmol/L values here represent average blood glucose, which is what HbA1c reflects. Estimated using the ADAG formula.

This tool is for educational purposes only and does not replace professional medical advice. Always consult your healthcare provider for diagnosis and treatment decisions.

Blood Glucose Conversion Chart

Average blood glucose values and their equivalents across units. HbA1c reflects your average blood sugar over ~3 months.

Avg. mg/dL Avg. mmol/L Est. HbA1c % Range
70 3.9 4.1% Normal
80 4.4 4.4% Normal
90 5.0 4.8% Normal
100 5.6 5.1% Normal
110 6.1 5.5% Normal
114 6.3 5.6% Normal
117 6.5 5.7% Prediabetes
120 6.7 5.8% Prediabetes
126 7.0 6.0% Prediabetes
131 7.3 6.2% Prediabetes
137 7.6 6.4% Prediabetes
140 7.8 6.5% Diabetes
154 8.6 7.0% Diabetes
170 9.4 7.5% Diabetes
183 10.2 8.0% Diabetes
200 11.1 8.6% Diabetes
240 13.3 10.0% Diabetes
300 16.7 12.1% Diabetes

Ranges classified by estimated HbA1c: Normal < 5.7%, Prediabetes 5.7–6.4%, Diabetes ≥ 6.5%.

What Do the Ranges Mean?

Low (Hypoglycemia)
< 70 mg/dL
< 3.9 mmol/L

Blood sugar is below the normal range. May cause shakiness, confusion, or dizziness. Eat fast-acting glucose to bring levels up.

Normal
HbA1c < 5.7%
~70 – 117 mg/dL · 3.9 – 6.5 mmol/L

Long-term blood sugar is in the healthy range. No action needed beyond routine checkups.

Prediabetes
HbA1c 5.7 – 6.4%
~117 – 140 mg/dL · 6.5 – 7.8 mmol/L

Blood sugar is higher than normal but below the diabetes threshold. Lifestyle changes (e.g., diet and exercise) can often reverse it.

Diabetes
HbA1c ≥ 6.5%
≥ 140 mg/dL · ≥ 7.8 mmol/L

An HbA1c of 6.5% or higher on two separate tests indicates diabetes. Medical management is recommended.

How the Conversions Work

mg/dL ↔ mmol/L

Both units measure blood glucose concentration. The US and Japan use mg/dL; most other countries use mmol/L. The conversion factor is 18.016, commonly rounded to 18.

mmol/L = mg/dL ÷ 18.016

mg/dL = mmol/L × 18.016

Glucose → Est. HbA1c

HbA1c reflects ~3 months of average blood sugar. The ADAG study formula estimates HbA1c from mean glucose.

HbA1c = (mg/dL + 46.7) ÷ 28.7

mg/dL = (HbA1c × 28.7) − 46.7

Frequently Asked Questions

How do you convert mmol/L to mg/dL?
Multiply the mmol/L value by 18 (more precisely 18.016). For example, 5 mmol/L × 18 = 90 mg/dL, and 7 mmol/L × 18 = 126 mg/dL. The calculator above does this instantly in both directions.
How do you convert mg/dL to mmol/L?
Divide the mg/dL value by 18 (more precisely 18.016). For example, 100 mg/dL ÷ 18 = 5.6 mmol/L, and 140 mg/dL ÷ 18 = 7.8 mmol/L.
What is the conversion factor for blood sugar units?
The conversion factor between mmol/L and mg/dL is 18.016, usually rounded to 18. Multiply mmol/L by 18 to get mg/dL, or divide mg/dL by 18 to get mmol/L. The factor comes from the molar mass of glucose.
What is the difference between mmol/L and mg/dL?
They are two units for the same thing: the concentration of glucose in your blood. mmol/L counts the number of glucose molecules, while mg/dL measures their weight. The US and Japan report blood sugar in mg/dL, while the UK, Canada, Australia, and most of Europe use mmol/L. A reading of 5.6 mmol/L is the same as 100 mg/dL.
How do you convert blood sugar to A1C?
A1C is estimated from your average glucose using the ADAG formula: A1C (%) = (average mg/dL + 46.7) ÷ 28.7. For example, an average of 120 mg/dL (6.7 mmol/L) is about 5.8% A1C. Enter any value in the calculator above to see the estimate.

Sources

Learn blood sugar management through play

Glycohero is an educational game that teaches you which foods raise or lower blood glucose and why.

Download on iOS