Blood Glucose to A1C Converter
Convert between average blood glucose and HbA1c values for diabetes management: type in either box.
Key facts
- Estimated average glucose (mg/dL) = 28.7 × A1C − 46.7, so an A1C of 7% is about 154 mg/dL (8.6 mmol/L).
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More optionsLab A1C · %
A CGM app reports a GMI (glucose management indicator) from at least 14 days of readings: GMI % = 3.31 + 0.02392 × mean glucose in mg/dL (Bergenstal et al., Diabetes Care 2018). It reads a little higher than the lab-A1C estimate at averages below about 154 mg/dL and lower above it, and can differ from your lab A1C.
ExampleEstimated average glucose
108mg/dL
Normal (non-diabetic)A1C 5.4% ≈ 108 mg/dL average glucose.
- Normal under 5.7%
- Prediabetes 5.7–6.4%
- Diabetes range 6.5% and up
- In mmol/L
- 6.0 mmol/L
- A1C in mmol/mol (IFCC)
- 36 mmol/mol
General information from published research, not a diagnosis or medical advice. Talk to a doctor before changing medication or treatment. Only a lab A1C test can diagnose diabetes. If a reading worries you, contact your care team. SourcesTerms
How it’s worked outADAG equation (Nathan et al., 2008)
A1C = (average glucose in mg/dL + 46.7) ÷ 28.7
(108.3 + 46.7) ÷ 28.7 = 5.40%
mmol/L = mg/dL ÷ 18 · IFCC mmol/mol = (% − 2.15) × 10.929. Results are approximations; individual variations occur.
How this works: Method, 3 sources, Checked against 1 worked example,
How this works
Method
A lab A1C and average glucose are converted with the ADAG equation: estimated average glucose (mg/dL) = 28.7 × A1C − 46.7. In CGM mode it uses the Glucose Management Indicator instead, GMI (%) = 3.31 + 0.02392 × mean glucose (mg/dL); mmol/L = mg/dL ÷ 18 and IFCC mmol/mol = (% − 2.15) × 10.929. The result is labelled normal below 5.7%, prediabetes at 5.7–6.4% and in the diabetes range from 6.5%.
Sources
- Translating the A1C Assay Into Estimated Average Glucose Values (ADAG) (Diabetes Care, 2008)
- Glucose Management Indicator (GMI): A New Term for Estimating A1C From Continuous Glucose Monitoring (Diabetes Care, 2018)
- Standards of Care in Diabetes (American Diabetes Association)
How it’s tested
One worked example for this page is checked by automated tests before every release: given the inputs, the tool must show the expected answer.
Limits
General information from published research, not a diagnosis or medical advice. Talk to a doctor before changing medication or treatment. Only a lab A1C test can diagnose diabetes. If a reading worries you, contact your care team.
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Changes
- Added a printable report with the A1C and glucose ruler, the conversion table and the working.
- Added key facts with the formulas and A1C ranges; the disclaimer became one quiet line under the result.
- Redesigned: one ruler that shows A1C and average glucose together, a mode for CGM averages (GMI), IFCC mmol/mol units and a conversion table you can tap.
- Added suggested next steps.
- Results now update as you type, with a gauge showing where the A1C falls.
Frequently Asked Questions
What is HbA1c and why is it important?
HbA1c (glycated hemoglobin) is a blood test that measures your average blood sugar levels over the past 2 to 3 months. It reflects the percentage of hemoglobin proteins in your blood that are coated with sugar. It is a key metric for diagnosing and managing diabetes because it provides a longer-term picture than a single glucose reading.
How does A1C relate to average blood glucose?
A1C and average blood glucose are related through the ADAG equation (Nathan et al., Diabetes Care 2008): estimated average glucose (mg/dL) = 28.7 × A1C − 46.7, or A1C = (Average Glucose in mg/dL + 46.7) / 28.7. For example, an A1C of 7% corresponds to an average blood glucose of approximately 154 mg/dL (8.6 mmol/L). Higher A1C values indicate higher average glucose levels over the past 2-3 months.
What are the target A1C levels?
For most adults with diabetes, the American Diabetes Association recommends a target A1C below 7%. Normal A1C is below 5.7%, prediabetes ranges from 5.7% to 6.4%, and diabetes is diagnosed at 6.5% or higher. Your doctor may set a different target based on your age, health conditions, and risk of hypoglycemia.
How often should A1C be tested?
The ADA recommends A1C testing at least twice a year for people meeting treatment goals, and quarterly for those whose therapy has changed or who are not meeting glycemic goals. Your healthcare provider may recommend more frequent testing if your blood sugar levels are not well controlled.
What factors can affect A1C accuracy?
Several conditions can affect A1C results, including anemia, hemoglobin variants (such as sickle cell trait), kidney disease, liver disease, recent blood transfusions, and certain medications. Pregnancy can also affect A1C readings. If you have any of these conditions, discuss alternative monitoring methods with your healthcare provider.