Convert between A1C percentage and estimated average glucose. Uses the ADAG formula validated in Diabetes Care (2008).
A1C converts to estimated average blood sugar using the formula: eAG (mg/dL) = 28.7 x A1C - 46.7. An A1C of 7.0% equals approximately 154 mg/dL average blood sugar. Below 5.7% is normal, 5.7-6.4% is prediabetes, 6.5%+ indicates diabetes per ADA criteria.
Written by Ash K · Last updated: June 2026 · Sources cited below
Your A1C measures average blood sugar over the past 2–3 months. This converter translates A1C percentages to estimated average glucose (eAG) and vice versa — because "A1C of 7%" is meaningless until you know that equals approximately 154 mg/dL average blood sugar.
The conversion uses the ADAG formula validated in a 2008 study published in Diabetes Care, which established the relationship between A1C and average glucose across 507 participants.
Key Takeaway: A1C reflects your average blood sugar over 2–3 months — not a single reading. An A1C of 5.7% or above indicates prediabetes per ADA criteria. An A1C of 6.5% or above indicates diabetes. The conversion formula: estimated average glucose (mg/dL) = 28.7 × A1C − 46.7.
| A1C (%) | Estimated Average Blood Sugar (mg/dL) | Estimated Average (mmol/L) | Classification |
|---|---|---|---|
| 4.0 | 68 | 3.8 | Normal |
| 5.0 | 97 | 5.4 | Normal |
| 5.5 | 111 | 6.2 | Normal |
| 5.7 | 117 | 6.5 | Prediabetes threshold |
| 6.0 | 126 | 7.0 | Prediabetes |
| 6.4 | 137 | 7.6 | Prediabetes (upper) |
| 6.5 | 140 | 7.8 | Diabetes threshold |
| 7.0 | 154 | 8.6 | Diabetes — ADA target for most adults |
| 8.0 | 183 | 10.2 | Diabetes — elevated risk |
| 9.0 | 212 | 11.8 | Diabetes — high risk of complications |
| 10.0 | 240 | 13.3 | Diabetes — significantly elevated |
| 12.0 | 298 | 16.5 | Diabetes — urgent management needed |
Source: ADAG Study Group, Diabetes Care, 2008. ADA Standards of Care, 2024.
A1C Scale: Normal → Prediabetes → Diabetes
The formula is straightforward:
eAG (mg/dL) = 28.7 × A1C − 46.7
Example: A1C of 7.0% → 28.7 × 7.0 − 46.7 = 154 mg/dL
To convert blood sugar to A1C: A1C = (eAG + 46.7) / 28.7
Example: Average blood sugar of 150 mg/dL → (150 + 46.7) / 28.7 = 6.85%
Tip: If your glucometer shows readings in mmol/L (common outside the US), convert to mg/dL first by multiplying by 18. Example: 8.5 mmol/L × 18 = 153 mg/dL. Or use this converter directly — it handles both units.
The American Diabetes Association (ADA) sets these diagnostic criteria and treatment targets:
Below 5.7% — Normal. Average blood sugar below 117 mg/dL. No diabetes concerns with this result.
5.7–6.4% — Prediabetes. Average blood sugar 117–137 mg/dL. Research shows that lifestyle changes (moderate weight loss, regular exercise, dietary adjustments) can reduce the risk of progressing to diabetes by 58%, according to the Diabetes Prevention Program trial.
6.5% or higher — Diabetes. Diagnosis requires confirmation with a second test. For most adults with diabetes, the ADA recommends an A1C target below 7.0% (average glucose ~154 mg/dL). Tighter targets may be appropriate for younger, healthier patients. Less strict targets (below 8%) may be appropriate for older adults or those with complication risk.
Note: A1C of 6.5% is the diagnostic threshold, but it's not a cliff edge. Someone at 6.4% may be functionally identical to someone at 6.6%. The clinical significance is in the pattern over time — is your A1C trending up, stable, or improving?
A1C Ranges — What Your Number Means
A1C measures glucose attachment to hemoglobin over the red blood cell lifespan (~120 days). Any condition that alters red blood cell turnover affects A1C accuracy:
Iron-deficiency anemia can falsely elevate A1C — fewer red blood cells live longer, accumulating more glucose.
Hemoglobin variants (sickle cell trait, hemoglobin C/D/E) can interfere with some A1C assay methods, producing falsely high or low results.
Kidney disease can lower A1C due to increased red blood cell turnover and erythropoietin use.
Recent blood loss or transfusion dilutes the hemoglobin pool and can produce temporarily inaccurate A1C.
Warning: If your A1C seems inconsistent with your daily glucose readings, tell your provider. Alternative markers like fructosamine or glycated albumin can assess glucose control over shorter timeframes (2–3 weeks) and aren't affected by red blood cell lifespan issues.
Pregnancy: A1C is less reliable during pregnancy due to physiological changes in red blood cell turnover. Most providers use oral glucose tolerance testing (OGTT) for gestational diabetes diagnosis instead.
If you track your blood sugar at home with a glucometer, you can estimate what your next A1C will be.
Average your last 90 days of fasting blood sugar readings. Apply the reverse formula: A1C = (average mg/dL + 46.7) / 28.7.
This estimate won't match your lab A1C exactly — A1C captures post-meal glucose too, which home fasting readings miss. But it provides a useful ballpark.
For monitoring your blood sugar ranges over time, see our blood sugar levels by age guide.
Bottom Line: A1C converts directly to estimated average blood sugar using the ADAG formula. Below 5.7% is normal, 5.7–6.4% is prediabetes, 6.5%+ is diabetes. The conversion helps you understand what your A1C actually means in daily glucose terms. But A1C can be misleading in certain conditions — always interpret with your provider.
What A1C level is diabetic?
An A1C of 6.5% or higher indicates diabetes according to ADA diagnostic criteria, confirmed by a second test. This corresponds to an estimated average blood sugar of approximately 140 mg/dL.
What does an A1C of 7 mean in blood sugar?
An A1C of 7.0% corresponds to an estimated average blood sugar of 154 mg/dL (8.6 mmol/L). This is the ADA-recommended treatment target for most adults with diabetes.
What blood sugar level equals an A1C of 5.7?
A1C 5.7% — the prediabetes threshold — corresponds to an estimated average glucose of approximately 117 mg/dL (6.5 mmol/L).
How accurate is the A1C to blood sugar conversion?
The ADAG formula is validated but represents a population average. Individual variation exists — your actual average glucose can differ from the estimated value by ±15 mg/dL. The conversion is most useful for understanding general trends, not for precise glucose management.
How often should A1C be tested?
The ADA recommends A1C testing at least twice yearly for people meeting treatment goals, and quarterly for those whose therapy has changed or who aren't meeting targets.
This converter is for educational purposes. A1C interpretation requires clinical context. Consult your healthcare provider for diagnosis and treatment decisions.
This tool is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your healthcare provider with questions about your health.