Blood Glucose Units: Converting mg/dL to mmol/L and A1C to Average Glucose
October 29, 2026
Blood glucose is reported in milligrams per deciliter (mg/dL) in the United States and in millimoles per liter (mmol/L) in most other countries. Converting between them is a matter of the molar mass of glucose, about 180.16 g/mol: mmol/L = mg/dL ÷ 18.016, and mg/dL = mmol/L × 18.016. So 100 mg/dL is 5.55 mmol/L, and 126 mg/dL is 6.99 mmol/L, close to 7.0.
Hemoglobin A1C, expressed as a percentage, reflects average blood glucose over roughly the past three months. The estimated average glucose (eAG) can be calculated from it: eAG (mg/dL) = 28.7 × A1C − 46.7. An A1C of 7% gives 28.7 × 7 − 46.7 = 154.2 mg/dL, or 8.6 mmol/L. This article is for information and unit conversion only; use targets and decisions from your healthcare team.
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The values below show common thresholds in both units. Reference ranges used for diagnosis and treatment targets are set by medical organizations and may differ by country, test conditions, and individual circumstances. For example, a fasting glucose of 70 to 99 mg/dL (3.9 to 5.5 mmol/L) is generally considered normal, 100 to 125 mg/dL (5.6 to 6.9 mmol/L) as prediabetes range, and 126 mg/dL (7.0 mmol/L) or above on repeated testing as consistent with diabetes, according to widely used criteria. Only a clinician can interpret your results.
| mg/dL | mmol/L | Context |
|---|---|---|
| 70 | 3.9 | Lower limit of typical fasting range |
| 100 | 5.6 | Upper limit of normal fasting |
| 126 | 7.0 | Fasting threshold for diabetes diagnosis |
| 140 | 7.8 | Two-hour post-meal level used in testing |
| 180 | 10.0 | Common upper post-meal target in some guidance |
| 250 | 13.9 | High reading; may need attention |
A1C and Estimated Average Glucose
A1C measures the percentage of hemoglobin with glucose attached. The ADAG study established the relationship eAG = 28.7 × A1C − 46.7 mg/dL. Examples: A1C 5.7% gives 117 mg/dL (6.5 mmol/L); 6.5% gives 140 mg/dL (7.8 mmol/L); 8% gives 183 mg/dL (10.1 mmol/L); 10% gives 240 mg/dL (13.3 mmol/L). In many guidelines, 5.7% to 6.4% is the prediabetes range and 6.5% or higher indicates diabetes, with an individualized treatment target often below 7% for many adults. The equation represents population averages: individual relationships vary with factors such as anemia, hemoglobin variants, and kidney disease.
Using Different Meters
Meters and continuous glucose monitors can display in either unit, usually adjustable in settings. When reading international articles, check the unit. When traveling or using a device bought abroad, make sure that you are reading in the right unit; confusing 6 mmol/L (108 mg/dL) with 6 mg/dL would be dangerous in either direction. Home meters have an accuracy tolerance of about ±15% under standards, so small differences between readings are expected.
Related Lab Units
Cholesterol is reported in mg/dL in the US and mmol/L elsewhere, but the conversion factor is different: multiply mmol/L by 38.67 for total, LDL, and HDL cholesterol, and by 88.57 for triglycerides. Never apply the glucose factor to other substances. Ask your clinician or pharmacist for help if you are unsure of a unit.
Frequently Asked Questions
How do I convert mg/dL to mmol/L for glucose?
Divide by 18.016.
What is 126 mg/dL in mmol/L?
About 7.0 mmol/L.
What is the formula for eAG from A1C?
28.7 × A1C − 46.7 in mg/dL.
What A1C corresponds to 154 mg/dL?
About 7%.
Does the cholesterol conversion use the same factor?
No. Cholesterol uses about 38.67, and triglycerides 88.57.