HbA1c to average glucose: conversion chart
Updated October 31, 2026 · 10 sources · Written by the AumniVIDA team
UnitsShort answer
Estimated average glucose (eAG) in mg/dL equals 28.7 x A1c minus 46.7, from the ADAG study of 507 people. An A1c of 6% is about 126 mg/dL (7.0 mmol/L)7.0 mmol/L (126 mg/dL), 7% about 154 mg/dL (8.6 mmol/L)8.6 mmol/L (154 mg/dL) and 8% about 183 mg/dL (10.2 mmol/L)10.2 mmol/L (183 mg/dL). Individual averages vary widely around each estimate .
Estimated average glucose for each HbA1c, with ADAG 95% limits
- A1c 5%97 mg/dL estimated average glucose5.4 mmol/L estimated average glucose
- A1c 6%126 mg/dL estimated average glucose7 mmol/L estimated average glucose
- A1c 7%154 mg/dL estimated average glucose8.5 mmol/L estimated average glucose
- A1c 8%183 mg/dL estimated average glucose10.2 mmol/L estimated average glucose
- A1c 9%212 mg/dL estimated average glucose11.8 mmol/L estimated average glucose
- A1c 10%240 mg/dL estimated average glucose13.3 mmol/L estimated average glucose
- A1c 11%269 mg/dL estimated average glucose14.9 mmol/L estimated average glucose
- A1c 12%298 mg/dL estimated average glucose16.5 mmol/L estimated average glucose
Show the data
| Item | Value (mg/dL estimated average glucose) | Low | High | Note |
|---|---|---|---|---|
| A1c 5% | 97 | 76 | 120 | |
| A1c 6% | 126 | 100 | 152 | |
| A1c 7% | 154 | 123 | 185 | |
| A1c 8% | 183 | 147 | 217 | |
| A1c 9% | 212 | 170 | 249 | |
| A1c 10% | 240 | 193 | 282 | |
| A1c 11% | 269 | 217 | 314 | |
| A1c 12% | 298 | 240 | 347 |
Key takeaways
How do you convert A1c to average glucose?
Multiply your A1c by 28.7 and subtract 46.7 to get estimated average glucose in mg/dL, or multiply by 1.5944 and subtract 2.594 for mmol/L. This is the ADAG regression, and the table gives each value with its 95% range [1].
Worked example: an A1c of 6.5% gives 28.7 x 6.5 minus 46.7, or about 140 mg/dL (7.8 mmol/L)7.8 mmol/L (140 mg/dL). An A1c of 5.7% gives about 117 mg/dL (6.5 mmol/L)6.5 mmol/L (117 mg/dL) [1].
The HbA1c chart lists every value from 4% to 14%, including mmol/mol. Remember that the published ADAG table covered 5% to 12% [1].
| A1c (%) | eAG (mg/dL) | 95% range (mg/dL) | eAG (mmol/L) | 95% range (mmol/L) |
|---|---|---|---|---|
| 5 | 97 | 76 to 120 | 5.4 | 4.2 to 6.7 |
| 6 | 126 | 100 to 152 | 7.0 | 5.5 to 8.5 |
| 7 | 154 | 123 to 185 | 8.6 | 6.8 to 10.3 |
| 8 | 183 | 147 to 217 | 10.2 | 8.1 to 12.1 |
| 9 | 212 | 170 to 249 | 11.8 | 9.4 to 13.9 |
| 10 | 240 | 193 to 282 | 13.4 | 10.7 to 15.7 |
| 11 | 269 | 217 to 314 | 14.9 | 12.0 to 17.5 |
| 12 | 298 | 240 to 347 | 16.5 | 13.3 to 19.3 |
What was the ADAG study?
The A1c-Derived Average Glucose (ADAG) study measured glucose about 2,700 times per person over 3 months in 507 people with type 1, type 2 or no diabetes at 10 international centers, then compared it with a central lab A1c. The linear fit had R squared 0.84 [1].
Participants combined at least 2 days of CGM every month with seven-point finger-stick profiles at least 3 days a week. The group included 268 people with type 1 diabetes, 159 with type 2 and 80 without diabetes [1].
The regression did not differ significantly by age, sex, diabetes type, race or ethnicity, or smoking, which is why one formula is used for most people. People with known sickle cell trait or anemia were excluded before the analysis, so the formula does not cover them [1].
Before ADAG, A1c was reported only as a percentage that many patients found hard to relate to their meter readings. The study was designed so that labs and clinicians could report A1c in the same units people see on a glucose meter. It also checked that the relationship held across continents, with centers in North America, Europe, Africa and Asia [1].
Separate regressions using only CGM data (28.0 x A1c minus 36.9) or only finger-stick profiles (29.1 x A1c minus 50.7) gave similar results, which supports the combined formula [1].
How accurate is the A1c to average glucose formula?
It is accurate for groups and approximate for individuals. The standard error of the prediction was 15.7 mg/dL overall, rising from 13.4 mg/dL at an A1c of 6% to 18.0 mg/dL at 8%, so two people with the same A1c can differ by 60 mg/dL or more in true average glucose [1].
Picture the ADAG scatter as a cloud around a straight line. The line gives the central estimate; the cloud widens as A1c rises. At 7%, the 95% range of true averages ran from 123 to 185 mg/dL, and at 9% from 170 to 249 mg/dL [1].
Much of that spread comes from biology, not error. Red cells live for different lengths of time in different people, and longer-lived cells collect more glucose at the same average [4] [5].
Estimated average glucose for each HbA1c, with ADAG 95% limits
- A1c 5%97 mg/dL estimated average glucose5.4 mmol/L estimated average glucose
- A1c 6%126 mg/dL estimated average glucose7 mmol/L estimated average glucose
- A1c 7%154 mg/dL estimated average glucose8.5 mmol/L estimated average glucose
- A1c 8%183 mg/dL estimated average glucose10.2 mmol/L estimated average glucose
- A1c 9%212 mg/dL estimated average glucose11.8 mmol/L estimated average glucose
- A1c 10%240 mg/dL estimated average glucose13.3 mmol/L estimated average glucose
- A1c 11%269 mg/dL estimated average glucose14.9 mmol/L estimated average glucose
- A1c 12%298 mg/dL estimated average glucose16.5 mmol/L estimated average glucose
Show the data
| Item | Value (mg/dL estimated average glucose) | Low | High | Note |
|---|---|---|---|---|
| A1c 5% | 97 | 76 | 120 | |
| A1c 6% | 126 | 100 | 152 | |
| A1c 7% | 154 | 123 | 185 | |
| A1c 8% | 183 | 147 | 217 | |
| A1c 9% | 212 | 170 | 249 | |
| A1c 10% | 240 | 193 | 282 | |
| A1c 11% | 269 | 217 | 314 | |
| A1c 12% | 298 | 240 | 347 |
What is GMI and how is it different from A1c?
GMI, the glucose management indicator, converts CGM mean glucose into an estimated A1c: GMI (%) = 3.31 + 0.02392 x mean glucose in mg/dL. It often differs from a lab A1c, by 0.4 points or more in 71% of people without diabetes in one study [2] [3].
The formula was renamed from estimated A1c in 2018 to make clear it is a different measure, not a prediction of the lab test [2]. In people without diabetes, GMI ran 0.59 points higher than lab HbA1c on average [3].
A consistent gap between your GMI and lab A1c is common and usually reflects your red cell biology. Many clinicians use CGM metrics such as time in range alongside A1c rather than instead of it [6] [7].
When does the A1c to glucose conversion not apply?
The conversion does not apply well when red cell lifespan or hemoglobin is unusual: anemia, iron deficiency, recent blood loss or transfusion, hemoglobin variants, pregnancy and advanced kidney disease. ADAG excluded people with sickle cell trait and anemia [1] [8].
In these cases, measured glucose from a meter or CGM is a better guide to average glucose than any number derived from A1c [7] [9]. See when HbA1c can be misleading for the full list with effect sizes.
How do you calculate A1c from average glucose?
Rearrange the ADAG formula: A1c (%) = (average glucose in mg/dL + 46.7) / 28.7. An average of 120 mg/dL corresponds to about 5.8%, 140 mg/dL to about 6.5% and 150 mg/dL to about 6.9% [1].
This reverse calculation uses the same regression as eAG. For CGM users, GMI is the purpose-built version of this estimate, with a slightly different formula [2].
The result is only as good as the average you put in. An average from a few finger-stick checks, mostly taken before meals, will underestimate true average glucose and so underestimate A1c. A CGM average over at least 2 weeks is the closest practical input; the time in range consensus recommends 14 days of data for reliable metrics [6].
| Average glucose (mg/dL) | Average glucose (mmol/L) | Estimated A1c (%) | Estimated A1c (mmol/mol) |
|---|---|---|---|
| 100 | 5.6 | 5.1% | 32 |
| 110 | 6.1 | 5.5% | 36 |
| 120 | 6.7 | 5.8% | 40 |
| 130 | 7.2 | 6.2% | 44 |
| 140 | 7.8 | 6.5% | 48 |
| 150 | 8.3 | 6.9% | 51 |
| 160 | 8.9 | 7.2% | 55 |
| 180 | 10.0 | 7.9% | 63 |
| 200 | 11.1 | 8.6% | 70 |
More about HbA1c
- HbA1c: the full guideHbA1c (A1c) is the percentage of hemoglobin in red blood cells that has glucose attached.
- HbA1c chart: normal, prediabetes and diabetes rangesA normal HbA1c is below 5.7% (39 mmol/mol).
- How to lower HbA1cWeight loss, diet pattern, structured exercise and medication lower HbA1c most.
- What does a high HbA1c mean?A high HbA1c means more hemoglobin has glucose attached, usually because average glucose has been raised for months.
- HbA1c test: fasting, home kits and how oftenThe HbA1c test needs no fasting and is unaffected by a recent meal, stress or exercise.
Protocols that act on HbA1c
- Low-glycemic dietA low-glycemic diet favors carbohydrate foods that raise blood sugar slowly, rated by the glycemic index (GI): 55 or less is low and 70 or more is high.
- Time-restricted eatingTime-restricted eating means eating all of the day's food and caloric drinks within a consistent daily window, usually 6 to 10 hours, and fasting the rest of the day.
- Ketogenic dietA ketogenic diet keeps carbohydrate under about 20 to 50 g a day so the body burns fat and makes ketones, defined in supervised programs as blood BHB of 0.5 to 3.0 mmol/L.
- Mediterranean dietThe Mediterranean diet is an eating pattern built on vegetables, fruit, legumes, whole grains, nuts, fish and olive oil as the main fat, with little red or processed meat, butter or sweets.
Common questions
Sources
- 1.Nathan DM, Kuenen J, Borg R, Zheng H, Schoenfeld D, Heine RJ; A1c-Derived Average Glucose Study Group. Translating the A1C assay into estimated average glucose values. Diabetes Care, 2008. doi:10.2337/dc08-0545
- 2.Bergenstal RM, Beck RW, Close KL, et al. Glucose Management Indicator (GMI): A New Term for Estimating A1C From Continuous Glucose Monitoring. Diabetes Care, 2018. doi:10.2337/dc18-1581
- 3.Shah VN, Vigers T, Pyle L, Calhoun P, Bergenstal RM. Discordance Between Glucose Management Indicator and Glycated Hemoglobin in People Without Diabetes. Diabetes Technology and Therapeutics, 2023. doi:10.1089/dia.2022.0544
- 4.Cohen RM, Franco RS, Khera PK, et al. Red cell life span heterogeneity in hematologically normal people is sufficient to alter HbA1c. Blood, 2008. doi:10.1182/blood-2008-04-154112
- 5.Bunn HF, Haney DN, Kamin S, Gabbay KH, Gallop PM. The biosynthesis of human hemoglobin A1c. Slow glycosylation of hemoglobin in vivo. Journal of Clinical Investigation, 1976. doi:10.1172/JCI108436
- 6.Battelino T, Danne T, Bergenstal RM, et al. Clinical Targets for Continuous Glucose Monitoring Data Interpretation: Recommendations From the International Consensus on Time in Range. Diabetes Care, 2019. doi:10.2337/dci19-0028
- 7.American Diabetes Association Professional Practice Committee for Diabetes. 6. Glycemic Goals, Hypoglycemia, and Hyperglycemic Crises: Standards of Care in Diabetes-2026. Diabetes Care, 2026. doi:10.2337/dc26-S006
- 8.American Diabetes Association Professional Practice Committee for Diabetes. 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes-2026. Diabetes Care, 2026. doi:10.2337/dc26-S002
- 9.Galindo RJ, de Boer IH, Neumiller JJ, Tuttle KR. Continuous Glucose Monitoring to Optimize Management of Diabetes in Patients with Advanced CKD. Clinical Journal of the American Society of Nephrology, 2023. doi:10.2215/CJN.04510422
- 10.Hoelzel W, Weykamp C, Jeppsson JO, et al. IFCC reference system for measurement of hemoglobin A1c in human blood and the national standardization schemes in the United States, Japan, and Sweden: a method-comparison study. Clinical Chemistry, 2004. doi:10.1373/clinchem.2003.024802