A1C Calculator – Convert A1C to eAG
Convert A1C % to estimated average glucose (eAG) in mg/dL or mmol/L, reverse eAG to A1C, and GMI conversion — all using the official ADA formula.
The table below shows the full A1C reference chart with estimated average glucose (eAG) in both mg/dL and mmol/L, plus IFCC values (mmol/mol) used outside the US.
| A1C (%) | eAG (mg/dL) | eAG (mmol/L) | IFCC (mmol/mol) | Status |
|---|---|---|---|---|
| 4.0% | 69 mg/dL | 3.8 mmol/L | 20 mmol/mol | Normal |
| 4.5% | 82 mg/dL | 4.6 mmol/L | 26 mmol/mol | Normal |
| 5.0% | 97 mg/dL | 5.4 mmol/L | 31 mmol/mol | Normal |
| 5.5% | 111 mg/dL | 6.2 mmol/L | 37 mmol/mol | Normal |
| 5.7% | 117 mg/dL | 6.5 mmol/L | 39 mmol/mol | Pre-diabetes |
| 6.0% | 126 mg/dL | 7 mmol/L | 42 mmol/mol | Pre-diabetes |
| 6.4% | 137 mg/dL | 7.6 mmol/L | 46 mmol/mol | Pre-diabetes |
| 6.5% | 140 mg/dL | 7.8 mmol/L | 48 mmol/mol | Diabetes |
| 7.0% | 154 mg/dL | 8.6 mmol/L | 53 mmol/mol | Diabetes |
| 7.5% | 169 mg/dL | 9.4 mmol/L | 58 mmol/mol | Controlled |
| 8.0% | 183 mg/dL | 10.2 mmol/L | 64 mmol/mol | High |
| 8.5% | 197 mg/dL | 10.9 mmol/L | 69 mmol/mol | High |
| 9.0% | 212 mg/dL | 11.8 mmol/L | 75 mmol/mol | Very High |
| 9.5% | 226 mg/dL | 12.6 mmol/L | 80 mmol/mol | Very High |
| 10.0% | 240 mg/dL | 13.4 mmol/L | 86 mmol/mol | Very High |
| 11.0% | 269 mg/dL | 14.9 mmol/L | 97 mmol/mol | Very High |
| 12.0% | 298 mg/dL | 16.5 mmol/L | 108 mmol/mol | Dangerous |
✱ 7.0% row highlighted — ADA recommended target for people with diabetes. Formula: eAG (mg/dL) = (28.7 × A1C%) − 46.7 (ADAG study, ADA 2008).
The ADA Formula (ADAG Study)
The official ADA formula to convert A1C to estimated average glucose is: eAG (mg/dL) = (28.7 × A1C%) − 46.7. For mmol/L: eAG (mmol/L) = (1.5944 × A1C%) − 2.5944. This is based on the A1C-Derived Average Glucose (ADAG) study published in 2008.
Reverse Conversion: eAG → A1C
To convert your average blood sugar back to an estimated A1C: A1C (%) = (eAG mg/dL + 46.7) ÷ 28.7. For example, an average glucose of 154 mg/dL corresponds to approximately 7.0% A1C.
GMI (Glucose Management Indicator)
GMI estimates A1C from CGM (continuous glucose monitor) data using: GMI (%) = 3.31 + (0.02392 × mean glucose mg/dL). It may differ from lab A1C by ±0.5% due to individual biological variation.
IFCC vs. NGSP (mmol/mol vs. %)
The US uses NGSP units (%), while most other countries use IFCC units (mmol/mol). Conversion: IFCC (mmol/mol) = 10.929 × (A1C% − 2.15). For example, 7.0% NGSP = 53 mmol/mol IFCC.
✅ Normal — Below 5.7%
An A1C below 5.7% indicates normal blood sugar levels. Equivalent to an average glucose below approximately 117 mg/dL (6.5 mmol/L). Annual monitoring is recommended.
⚠️ Prediabetes — 5.7% to 6.4%
Prediabetes means blood sugar is higher than normal but not yet diabetic. Lifestyle changes — diet, exercise, weight loss — can reverse prediabetes and prevent progression to type 2 diabetes. Testing every 1–2 years is recommended.
🔴 Diabetes — 6.5% or Higher
An A1C of 6.5% or above on two separate tests is diagnostic for diabetes. The ADA recommends a target of below 7.0% for most adults with diabetes to reduce the risk of complications including neuropathy, retinopathy, and cardiovascular disease.
🎯 ADA Target — Below 7.0%
For people already diagnosed with diabetes, the ADA recommends maintaining A1C below 7.0% (eAG ~154 mg/dL). Tighter targets (e.g. <6.5%) may apply for some patients. Less strict targets (<8%) may apply for elderly patients or those with frequent hypoglycemia.
A1C measures the percentage of hemoglobin in your blood coated with glucose. The lab converts this to estimated average glucose using the ADA formula: eAG (mg/dL) = (28.7 × A1C%) − 46.7. This reflects your average blood sugar over the past 2–3 months.
Use: eAG (mg/dL) = (28.7 × A1C%) − 46.7. For A1C of 7.0%, eAG = (28.7 × 7) − 46.7 = 154 mg/dL. In mmol/L, divide by 18.015: 154 ÷ 18 ≈ 8.6 mmol/L. Our calculator does this instantly.
Estimate your A1C from average glucometer readings: A1C (%) = (avg glucose mg/dL + 46.7) ÷ 28.7. This is an estimate — laboratory testing provides certified results. At-home A1C test kits are also available from pharmacies.
GMI (Glucose Management Indicator) estimates A1C from a CGM 14-day average: GMI (%) = 3.31 + (0.02392 × mean glucose mg/dL). It can differ from your lab A1C by ±0.5% due to individual variation in red blood cell turnover.
A1C is reported as a percentage of glycated hemoglobin. eAG (estimated average glucose) translates that percentage into mg/dL or mmol/L — the same units shown on your glucometer — making it easier to relate to daily readings.
People with well-controlled diabetes: every 6 months. Poorly controlled or recently adjusted medications: every 3 months. Prediabetes: every 1–2 years. Normal: discuss with your doctor, typically every 3 years.
Yes. Conditions that affect red blood cell turnover — sickle cell anaemia, iron deficiency anaemia, recent blood transfusion, or pregnancy — can cause false A1C readings. In these cases, doctors may use a fructosamine test instead.