Blood Sugar Converter – mg/dL to mmol/L and HbA1c Made Simple
The Blood Sugar Converter helps you translate glucose readings between the two units used around the world: mg/dL (milligrams per deciliter), the standard in the United States and Japan, and mmol/L(millimoles per liter), the SI unit used across Europe, Canada, Australia, and most international clinical guidelines. Whether you're reading a meter purchased abroad, interpreting a lab report from a different country, or simply double-checking a number from a doctor's visit, this tool gives you an instant, accurate conversion.
Why Two Units Exist
Blood glucose is fundamentally a concentration measurement, and different countries adopted different conventions decades ago. mg/dL expresses how many milligrams of glucose are dissolved per deciliter of blood, while mmol/L expresses the molar concentration directly. Neither unit is "more correct" — they simply reflect regional standards, and converting between them is purely arithmetic.
How the Conversion Works
Glucose has a fixed molar mass, which gives us an exact conversion factor of 18.0182. To convert mg/dL to mmol/L, divide by this factor; to go the other direction, multiply by it. For example, 180 mg/dL ÷ 18.0182 ≈ 9.99 mmol/L, and 5.5 mmol/L × 18.0182 ≈ 99.1 mg/dL. The converter performs this calculation instantly and lets you swap the input and output units with a single click.
Understanding the Clinical Range Indicator
Alongside the converted value, the tool displays a color-coded range label — hypoglycemic, normal, pre-diabetic, diabetic, or very high — based on commonly cited ADA and WHO threshold values for random or fasting glucose readings. A visual gauge bar fills proportionally to where your value sits within these ranges, giving you an at-a-glance sense of context alongside the precise number.
Converting HbA1c Between NGSP and IFCC
Glycated hemoglobin (HbA1c) reflects average blood sugar control over roughly the previous two to three months and is reported differently depending on region. The US and many labs use the NGSP/DCCT percentage format (e.g. 7.0%), while many European laboratories report the IFCC mmol/mol value (e.g. 53 mmol/mol). The converter applies the standard linear formula IFCC = (NGSP − 2.15) × 10.929to move between the two, so you can compare an overseas lab result with the format you're used to.
Estimated Average Glucose (eAG)
Because an HbA1c percentage alone can be hard to relate to daily meter readings, the American Diabetes Association publishes a formula to translate it into an estimated average glucose value: eAG (mg/dL) = 28.7 × HbA1c% − 46.7. This tool calculates eAG automatically whenever you enter an HbA1c value, displaying the result in both mg/dL and mmol/L so you can see how your long-term average compares to your day-to-day readings.
Reading the Reference Range Table
Below your converted result, a reference table lists typical glucose ranges in both units side by side — from hypoglycemic levels under 70 mg/dL (3.9 mmol/L) through the diabetic range starting around 126 mg/dL (7.0 mmol/L). Keeping both units visible together makes it easier to build an intuitive sense of how the two scales relate, especially if you frequently switch between devices or guidelines that use different units.
Who Uses This Tool
Patients managing diabetes who travel internationally, caregivers tracking readings from family members abroad, healthcare professionals reviewing records from other countries, and students learning clinical chemistry all benefit from a fast, reliable way to move between glucose unit systems without manual arithmetic or risk of error.
Accuracy and Precision
All conversions use the internationally recognized exact factor of 18.0182 for glucose and the standard NGSP/IFCC linear relationship for HbA1c. You can adjust the displayed precision for glucose conversions from 0 to 4 decimal places to match the level of detail shown on your meter or lab report.