Health
A1C Calculator
Convert A1C to eAG, estimate A1C from readings, and check ADA risk bands.
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A1C Workspace
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A1C to eAG
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About this calculator
Method, formulas, and limits.What this does
Converts hemoglobin A1C percentages to estimated average glucose (eAG) in mg/dL or mmol/L using the ADAG study formula, estimates A1C from a log of fingerstick glucose readings, and classifies results into ADA risk categories: normal, prediabetes, or diabetes range.
Who it is for
People with diabetes or prediabetes who want to understand their A1C results, track their average glucose levels from home readings, and see where they fall on the ADA clinical risk scale. Also useful for caregivers and health-conscious individuals monitoring their metabolic health.
How it works
The Convert tab applies the formula eAG = 28.7 × A1C - 46.7 to translate an A1C lab result into an estimated average glucose level, and vice versa. The Glucose Log tab averages your entered fingerstick readings and estimates an A1C from the mean. The Risk Check tab classifies any A1C value into the appropriate ADA range and provides a clinical note.
Limitations
Estimated A1C from fingerstick readings is not a substitute for a laboratory HbA1c test. The ADAG formula is a population average and individual results may vary. Glucose logs assume evenly distributed readings and may not capture all daily fluctuations.
Key calculations
- A1C to eAG (mg/dL)
- The ADAG study regression formula converts A1C percentage to estimated average glucose. eAG = 28.7 × A1C - 46.7. For example, a 7% A1C equals an eAG of approximately 154 mg/dL.
- A1C to eAG (mmol/L)
- The same conversion expressed in SI units for international use. eAG (mmol/L) = 1.594 × A1C - 2.594. A 7% A1C equals approximately 8.6 mmol/L.
- eAG to A1C (Reverse)
- Given an average glucose reading, estimate the corresponding A1C. A1C = (eAG + 46.7) / 28.7 for mg/dL, or A1C = (eAG + 2.594) / 1.594 for mmol/L.
- Average Glucose from Log
- Sum all glucose readings and divide by the count to find the mean, then apply the reverse ADAG formula to estimate A1C. avgGlucose = sum(readings) / count, estimatedA1C = (avgGlucose + 46.7) / 28.7
Reference ranges
- Normal Range
- A1C below 5.7% (eAG below 117 mg/dL / 6.5 mmol/L). Fasting glucose 70-100 mg/dL (3.9-5.6 mmol/L). No diabetes diagnosis. Maintain healthy diet and exercise.
- Prediabetes Range
- A1C 5.7-6.4% (eAG 117-137 mg/dL / 6.5-7.6 mmol/L). Fasting glucose 100-125 mg/dL (5.6-6.9 mmol/L). Lifestyle changes can reduce progression risk to type 2 diabetes.
- Diabetes Range
- A1C 6.5% or higher (eAG 140 mg/dL / 7.8 mmol/L or above). Fasting glucose 126 mg/dL (7.0 mmol/L) or higher. Medical management and regular monitoring are recommended.
- Glucose Variability
- Post-meal glucose can rise to 140-180 mg/dL (7.8-10.0 mmol/L) even in non-diabetic individuals. Diabetes management targets often aim for postprandial peaks below 180 mg/dL (10.0 mmol/L).
How to use it
- 1.Select your glucose unitToggle between mg/dL (US standard) and mmol/L (international standard) at the top of the calculator. All inputs and outputs will use your selected unit.
- 2.Use the Convert tabEnter an A1C percentage to see the equivalent estimated average glucose (eAG), or enter an eAG value to calculate the corresponding A1C. Results update live as you type.
- 3.Log your glucose readingsSwitch to the Glucose Log tab and add your fingerstick readings with measurement period tags (fasting, postprandial, bedtime). The calculator averages them and estimates your A1C from the log data.
- 4.Check your risk categoryGo to the Risk Check tab to see where your A1C falls on the ADA scale: Normal (< 5.7%), Prediabetes (5.7-6.4%), or Diabetes Range (≥ 6.5%). A clinical note provides context for each result.
- 5.Review your resultsCompare your estimated A1C from the glucose log against your lab-measured A1C. The risk check provides a visual category indicator with color coding and actionable clinical guidance.
It uses the ADAG study formula: eAG (mg/dL) = 28.7 x A1C - 46.7. For example, a 7% A1C converts to 154 mg/dL eAG. The reverse formula estimates A1C from an average glucose reading. The calculator supports both directions in the Convert tab.
No. Home readings are estimates. Only a lab HbA1c test measures glycated hemoglobin directly and is the gold standard for diagnosis and monitoring. The estimated A1C from a glucose log is useful for tracking trends between lab visits but should not be used for treatment decisions without consulting your doctor.
It supports mg/dL (used in the US) and mmol/L (used in most other countries). Switch the unit toggle at the top of the calculator and all inputs, conversions, and risk band thresholds will update automatically.
Below 5.7% is normal. 5.7% to 6.4% is prediabetes. 6.5% or higher is diabetes range. These thresholds come from the American Diabetes Association (ADA) clinical guidelines and are used internationally for diabetes screening and diagnosis.
More readings produce a more reliable estimate. A minimum of 7-14 readings across different times of day (fasting, after meals, bedtime) over a 1-2 week period provides a reasonable snapshot. The calculator shows the reading count so you can assess the confidence level of the estimate.
A1C is a percentage that measures glycated hemoglobin in your blood over the past 2-3 months. eAG (estimated Average Glucose) converts that percentage into the same mg/dL or mmol/L units you see on your glucose meter, making it easier to understand how your daily readings relate to your A1C result.
The A1C conversion and glucose log features work for any glucose monitoring context. However, gestational diabetes has different diagnostic thresholds and target ranges. Consult your healthcare provider for pregnancy-specific glucose targets and A1C interpretation.
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