HbA1c to Estimated Average Glucose (eAG) Calculator — ADA ADAG Study Standard
Convert hemoglobin A1c percentage (%) to estimated average glucose (eAG in mg/dL or mmol/L) to help patients understand 3-month glycemic control.
HbA1c to Average Glucose Calculator
Enter values below to calculate
Lab-measured A1c percentage.
This calculator is for informational and educational purposes. Results should be interpreted with clinical judgment and local guidelines.
What is Estimated Average Glucose (eAG)?
Estimated Average Glucose (eAG) translates a patient's glycated hemoglobin (HbA1c) percentage into the same unit (mg/dL or mmol/L) used in daily self-monitoring of blood glucose (SMBG). Validated by the A1C-Derived Average Glucose (ADAG) study published by Nathan et al. in 2008 and endorsed by the American Diabetes Association (ADA) and EASD, eAG provides a practical bridge between long-term A1c measurements and daily fingerstick or continuous glucose monitor (CGM) readings. The formula calculates the average blood glucose over the preceding 2 to 3 months (the average lifespan of human erythrocytes).
eAG (mg/dL) = 28.7 × HbA1c (%) − 46.7. eAG (mmol/L) = 1.59 × HbA1c (%) − 2.59. Standard non-diabetic A1c: < 5.7%. ADA target for non-pregnant adults with diabetes: < 7.0% (eAG ~154 mg/dL).
When to Use the HbA1c to eAG Converter
- Patient education in diabetes consultations: Translating abstract A1c percentages into familiar daily blood glucose numbers (mg/dL).
- Correlating glucometer / CGM average glucose with official 3-month laboratory HbA1c results.
- Monitoring therapeutic efficacy of oral hypoglycemic agents (Metformin, SGLT2i, DPP4i) or insulin therapy in Type 1 and Type 2 Diabetes.
ADA ADAG Study Conversion Formula
HbA1c to eAG (Conventional Units - mg/dL)
eAG (mg/dL) = 28.7 × HbA1c (%) − 46.7
HbA1c = 7.0% → eAG = 28.7 × 7.0 − 46.7 = 200.9 − 46.7 = 154.2 mg/dL
HbA1c to eAG (SI Units - mmol/L)
eAG (mmol/L) = 1.59 × HbA1c (%) − 2.59
HbA1c = 7.0% → eAG = 1.59 × 7.0 − 2.59 = 8.54 mmol/L
Variables
HbA1c Percentage (%)
NGSP-certified laboratory glycated hemoglobin percentage.
In conditions with altered red blood cell turnover (hemolytic anemia, hemoglobinopathies, severe iron deficiency, recent blood transfusion), HbA1c does not accurately reflect eAG.
HbA1c & eAG Diagnostic Reference Categories
ADA 2026 Clinical Practice Recommendations diagnostic thresholds.
| Range | Classification | Health Risk |
|---|---|---|
| < 5.7% (eAG < 117 mg/dL) | Normal Glycemia | Normal non-diabetic range. |
| 5.7%–6.4% (eAG 117–137 mg/dL) | Prediabetes (Increased Risk) | Impaired fasting glucose / glucose tolerance. Lifestyle intervention. |
| 6.5%–6.9% (eAG 140–151 mg/dL) | Diabetes — Sub-target | Diabetes diagnosed (≥ 6.5%). Excellent glycemic control if diabetic. |
| 7.0%–7.9% (eAG 154–180 mg/dL) | Diabetes — Moderate Control | ADA target for most adults is < 7.0%. Review medication adherence. |
| ≥ 8.0% (eAG ≥ 183 mg/dL) | Diabetes — Suboptimal Control | High risk of microvascular complications (retinopathy, nephropathy, neuropathy). Intensify therapy. |
Target A1c should be individualized: tighter targets (< 6.5%) for young patients without hypoglycemia; relaxed targets (< 8.0%) for frail elderly with severe hypoglycemia risk.
Limitations & Clinical Warnings
HbA1c is inaccurate in hemoglobin variants (HbS, HbC, HbE), pregnancy (2nd/3rd trimester), hemodialysis, and recent blood loss/transfusion.
eAG represents a 90-day mathematical average and does NOT reflect glycemic variability or asymptomatic hypoglycemia episodes.
Medical Disclaimer
Use eAG as an educational tool alongside CGM Time-in-Range (TIR) metrics and clinical laboratory testing.
References & Citations
- Nathan DM, Kuenen J, Borg R, et al.. “Translating the A1C assay into estimated average glucose values (ADAG Study)”. Diabetes Care. 2008. 31(8): 1473–1478. PMID: 18540046 | DOI: 10.2337/dc08-0545
Medically Reviewed
Reviewed by CliniqWise Clinical Advisory Board — Endocrinology Panel · Last updated: 2026-08-27 · Next review: 2027-02-27
Common Questions About HbA1c to Average Glucose Calculator
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