To convert A1C to average blood sugar, use eAG = 28.7 × A1C − 46.7 (mg/dL). An A1C of 7% equals an estimated average glucose of 154 mg/dL (8.6 mmol/L); 6% is 126 mg/dL. This formula comes from the ADAG study and is the one the American Diabetes Association uses.
The calculator works both ways (A1C to glucose, or average glucose to A1C) and also shows the IFCC unit (mmol/mol) that labs outside the US report, plus the ADA diagnostic category.
How to use the A1C calculator
- Choose the direction: A1C to average glucose, or average glucose to A1C.
- Enter your A1C in %, or your average glucose in mg/dL or mmol/L.
- Read the estimated average glucose (or estimated A1C), the value in the other unit, the IFCC value and the ADA category.
- For glucose to A1C, use an average over several weeks, for example from a CGM report or many meter readings, not a single reading.
How it's calculated
- eAG (mg/dL) = 28.7 × A1C − 46.7, and eAG (mmol/L) = 1.5944 × A1C − 2.594 (Nathan et al., 2008).
- A1C from glucose = (mg/dL + 46.7) ÷ 28.7, the same line solved the other way.
- IFCC (mmol/mol) = (A1C % − 2.152) ÷ 0.09148, from the NGSP–IFCC master equation (NGSP % = 0.09148 × IFCC + 2.152).
- mg/dL ↔ mmol/L: divide or multiply by 18.016, from glucose's molecular weight of 180.16 g/mol.
A1C to average glucose chart
| A1C | eAG (mg/dL) | eAG (mmol/L) |
|---|---|---|
| 5% | 97 | 5.4 |
| 5.5% | 111 | 6.2 |
| 5.7% | 117 | 6.5 |
| 6% | 126 | 7.0 |
| 6.5% | 140 | 7.8 |
| 7% | 154 | 8.6 |
| 7.5% | 169 | 9.4 |
| 8% | 183 | 10.2 |
| 8.5% | 197 | 11.0 |
| 9% | 212 | 11.8 |
| 9.5% | 226 | 12.6 |
| 10% | 240 | 13.4 |
| 11% | 269 | 14.9 |
| 12% | 298 | 16.5 |
Values at whole-number A1Cs match Table 2 of Nathan et al. (2008). The ADA calculator page shows 10.1 mmol/L at 8%; the paper's more precise equation gives 10.2.
Average glucose to A1C chart
| Average glucose (mg/dL) | mmol/L | Estimated A1C |
|---|---|---|
| 100 | 5.6 | 5.1% |
| 120 | 6.7 | 5.8% |
| 140 | 7.8 | 6.5% |
| 160 | 8.9 | 7.2% |
| 180 | 10.0 | 7.9% |
| 200 | 11.1 | 8.6% |
| 250 | 13.9 | 10.3% |
| 300 | 16.7 | 12.1% |
A1C % to IFCC mmol/mol
| A1C (NGSP %) | IFCC (mmol/mol) | ADA category |
|---|---|---|
| 5.7% | 39 | Prediabetes range (5.7–6.4%) |
| 6.5% | 48 | Diabetes range (≥ 6.5%) |
| 7% | 53 | Diabetes range (≥ 6.5%) |
| 8% | 64 | Diabetes range (≥ 6.5%) |
| 9% | 75 | Diabetes range (≥ 6.5%) |
Worked examples
A1C of 8.2%
eAG = 28.7 × 8.2 − 46.7 = 189 mg/dL (10.5 mmol/L). In IFCC units that is 66 mmol/mol, above the <7% goal the ADA says suits many adults.
CGM average of 9.0 mmol/L
9.0 × 18.016 = 162 mg/dL. A1C ≈ (162.1 + 46.7) ÷ 28.7 = 7.3%.
Lab result of 42 mmol/mol
A1C % = 0.09148 × 42 + 2.152 = 6.0%, which is in the prediabetes range (5.7–6.4%). The estimated average glucose is about 125 mg/dL.
A1C levels: normal, prediabetes and diabetes
NIDDK and the ADA Standards of Care 2026 use the same cut-offs: below 5.7% is normal, 5.7–6.4% is prediabetes and 6.5% or above is diabetes. A diagnosis needs a lab test with an NGSP-certified method. Without clear symptoms of high blood sugar, the ADA requires two abnormal results: two different tests taken at the same time (for example A1C and fasting glucose), or the same test repeated at two different times. A home A1C kit or this calculator cannot diagnose diabetes.
For people who already have diabetes, the ADA says an A1C goal below 7% (53 mmol/mol) suits many nonpregnant adults without severe hypoglycemia, and people using a CGM can aim for more than 70% time in range (70–180 mg/dL). Low blood sugar is defined as under 70 mg/dL (level 1) and under 54 mg/dL (level 2). Goals are personal, and less strict targets may be right for some people.
How accurate is eAG?
The ADAG study compared A1C with about 2,700 glucose readings per person over three months in 507 adults with type 1, type 2 or no diabetes (R² = 0.84). The relationship did not differ by age, sex, diabetes type, race/ethnicity or smoking, but individual averages spread widely around the line: at an A1C of 7% the 95% range was 123–185 mg/dL.
When A1C can be misleading
A1C shows your average blood sugar over roughly the past 3 months, because it measures glucose attached to hemoglobin in red blood cells. Anything that changes red blood cells can throw it off. NIDDK lists:
- iron-deficiency anemia (can make A1C falsely high);
- kidney failure or liver disease;
- hemoglobin variants, which are more common in people of African, Mediterranean or Southeast Asian heritage, and which some lab methods handle badly;
- recent blood loss, a blood transfusion, sickle cell disease or erythropoietin treatment.
If your A1C and your meter or CGM averages don't match, tell your care team rather than trusting either number alone.
When to see a doctor
This calculator is an educational estimate, not medical advice or a diagnosis. See a doctor if your A1C or average glucose falls in the prediabetes or diabetes range, if you have symptoms NIDDK and the ADA list such as increased urination, strong thirst, blurred vision, sores that do not heal or unexplained weight loss, or if your readings change a lot. Get urgent medical help if you feel very unwell with high readings, or if low blood sugar does not improve with treatment. Don't change medication based on this page. If weight is part of your plan, the weight loss by date calculator and EER calculator can help you set calorie targets to discuss with your care team.
Frequently asked questions
What is the formula to convert A1C to average glucose?
eAG (mg/dL) = 28.7 × A1C − 46.7, from the ADAG study (Nathan et al., 2008). In mmol/L: eAG = 1.5944 × A1C − 2.594.
What average glucose is an A1C of 7?
An A1C of 7% corresponds to an estimated average glucose of 154 mg/dL (8.6 mmol/L). In the ADAG study the 95% range at that A1C was 123–185 mg/dL.
What average glucose is an A1C of 6.5?
An A1C of 6.5% corresponds to about 140 mg/dL (7.8 mmol/L). 6.5% is also the ADA threshold for the diabetes range.
What A1C is an average glucose of 150?
An average glucose of 150 mg/dL corresponds to an A1C of about 6.9%.
How do I convert my glucose to A1C?
Use A1C = (average glucose in mg/dL + 46.7) ÷ 28.7, the ADAG formula rearranged. For example, an average of 120 mg/dL gives about 5.8%. Use an average over weeks, not one reading.
What A1C level means diabetes?
Per the ADA Standards of Care 2026, an A1C of 6.5% (48 mmol/mol) or higher is in the diabetes range and 5.7–6.4% (39–47 mmol/mol) is prediabetes. A diagnosis needs lab testing with an NGSP-certified method and, without clear symptoms, two abnormal results.
What is a normal A1C?
NIDDK lists below 5.7% as normal, 5.7–6.4% as prediabetes and 6.5% or above as diabetes.
What A1C should I aim for with diabetes?
The ADA Standards of Care 2026 say an A1C goal below 7% (53 mmol/mol) is appropriate for many nonpregnant adults without severe hypoglycemia, and that less strict goals may suit people with frailty, significant cognitive or functional limits, or severe other illnesses. Your own goal should be set with your care team.
How often should A1C be checked?
The ADA recommends assessing glycemic status at least twice a year, and more often (for example every 3 months) if you are not meeting your goals, have recently changed treatment, or have frequent or severe high or low blood sugar.
How do you convert mg/dL to mmol/L?
Divide mg/dL by 18.016 (from glucose's molecular weight of 180.16 g/mol), or multiply mmol/L by 18.016. For example 126 mg/dL = 7.0 mmol/L.
Why doesn't my A1C match my meter or CGM average?
The ADA notes that A1C and meter or CGM results can disagree because of high glucose variability, inaccurate meter or CGM readings, or an inaccurate A1C. NIDDK lists conditions that make A1C unreliable, including iron-deficiency anemia, kidney failure, liver disease, hemoglobin variants, recent blood loss or transfusion, and sickle cell disease.
Sources & method
- Nathan et al. (2008), Diabetes Care — Translating the A1C assay into estimated average glucose values (ADAG)
- American Diabetes Association — eAG/A1C conversion calculator
- ADA Standards of Care in Diabetes—2026, Section 2: Diagnosis and classification
- ADA Standards of Care in Diabetes—2026, Section 6: Glycemic goals and hypoglycemia
- NIDDK — The A1C test and diabetes
- NGSP — IFCC standardization and master equation
- PubChem — Glucose (molecular weight 180.16 g/mol)
Results are estimates for general information. Found an error? It helps everyone — see our methodology.