Health & Fitness
A1C ↔ Blood Glucose Converter
Convert between HbA1c percentage and estimated average glucose (eAG) in mg/dL or mmol/L using the ADA formula.
A1C
7%
Avg Glucose (mg/dL)
154.2
Avg Glucose (mmol/L)
8.6
Disclaimer: This tool is for educational purposes only and is not a medical device. Consult your healthcare provider for medical advice.
A1C reference ranges
| A1C Level | Category | eAG (mg/dL) |
|---|---|---|
| Below 5.7% | Normal | Below 117 |
| 5.7% – 6.4% | Prediabetes | 117 – 137 |
| 6.5% and above | Diabetes | 140 and above |
What is A1C?
The A1C test (hemoglobin A1c or HbA1c) measures your average blood glucose over approximately the past 2–3 months. Red blood cells live about 3 months, and glucose attaches to hemoglobin in proportion to blood sugar levels during that time. The percentage reflects what fraction of hemoglobin has glucose attached.
Estimated Average Glucose (eAG)
eAG converts your A1C into the same mg/dL units shown on a glucometer. The formula is:
eAG (mg/dL) = (28.7 × A1C%) − 46.7For example, an A1C of 7.0% corresponds to an eAG of approximately 154 mg/dL.
How A1C is measured
A1C is measured through a standard blood draw analyzed in a certified clinical laboratory - it is not the same as a finger-prick glucose reading from a home glucometer. The test measures the percentage of hemoglobin molecules that have glucose permanently bonded to them (glycation). Because red blood cells live about 90 days, the result reflects average glucose control over the past 2–3 months. Repeat testing is typically done every 3–6 months for people managing diabetes.
Limitations of A1C
A1C can give falsely high or low readings in certain conditions:
- Sickle cell trait or disease: Abnormal hemoglobin variants cause some A1C assays to read inaccurately. Alternative tests (fructosamine, continuous glucose monitoring) may be needed.
- G6PD deficiency: Causes increased red blood cell turnover, which can lower A1C readings relative to true average glucose.
- Iron-deficiency anemia: Reduced red blood cell turnover may falsely elevate A1C.
- Pregnancy: Increased red cell production during pregnancy lowers A1C, making it less reliable in the second and third trimesters.
Management targets
The reference table above shows diagnostic ranges. For people already diagnosed with diabetes, most guidelines recommend a target A1C of <7.0% (ADA) to minimize the risk of microvascular complications. Individual targets may be higher (7.5–8.5%) for older adults, those with hypoglycemia unawareness, or complex medical conditions. Always work with your healthcare provider to set a personalized goal.
International units (mmol/mol)
Many countries outside the US report A1C in IFCC units (mmol/mol) rather than DCCT percentages. The conversion formula is:
IFCC (mmol/mol) = (DCCT% − 2.15) × 10.929For example, 7.0% DCCT = (7.0 − 2.15) × 10.929 ≈ 53 mmol/mol. Most international lab reports and devices show both values.