A1C (HbA1c) is a blood test that reflects your average blood sugar level over the past 2-3 months. Converting A1C to estimated average glucose (eAG) helps you understand what your A1C means in the same mg/dL or mmol/L numbers you see on a glucose meter.
A1C Calculator
Enter a value between 4% and 20%
A1C Reference Ranges
| Category | A1C % | eAG mg/dL | eAG mmol/L |
|---|---|---|---|
| Normal | Below 5.7% | Below 117 | Below 6.5 |
| Pre-diabetes | 5.7% – 6.4% | 117 – 137 | 6.5 – 7.6 |
| Diabetes (ADA target) | Below 7% | Below 154 | Below 8.6 |
| Diabetes (high) | 7% and above | 154 and above | 8.6 and above |
How to Use the A1C Calculator
The A1C calculator converts your HbA1c percentage into estimated average glucose (eAG), making it easier to understand your long-term blood sugar control in the same units as your daily readings.
Step 1: Enter Your A1C Percentage
Type your most recent A1C result as reported on your lab report. A1C values typically range from 4% to 14% for clinical purposes. If you don't know your current A1C, ask your healthcare provider for your most recent lab results.
Step 2: View eAG Results
The calculator uses the ADA formula: eAG (mg/dL) = (28.7 × A1C%) − 46.7. Results are displayed in both mg/dL (used in the US) and mmol/L (used internationally). For example, an A1C of 7.0% converts to approximately 154 mg/dL or 8.6 mmol/L.
Understanding Your Result
The calculator shows a color-coded interpretation. Normal A1C is below 5.7% (eAG below 117 mg/dL). Pre-diabetes is 5.7–6.4% (eAG 117–137 mg/dL). For diagnosed diabetics, the ADA recommends keeping A1C below 7.0% (eAG below 154 mg/dL), though your personal target should be set by your doctor.
A1C vs Daily Blood Sugar Readings
Your A1C reflects a 2-3 month average of all your blood sugar readings, weighted toward more recent weeks. Daily glucose meter readings show point-in-time values that can vary significantly with meals, exercise, and stress. A1C gives the "big picture" while daily readings show the moment-to-moment pattern.
Frequently Asked Questions
Is this A1C calculator free?
Yes, completely free with no signup required. All calculations run locally in your browser.
Is my health data safe?
Yes, all calculations run in your browser. No data is sent to any server or stored remotely.
What is A1C and why does it matter?
A1C (HbA1c) measures the percentage of hemoglobin coated with sugar over the past 2-3 months. It is the primary test used to diagnose diabetes and monitor blood sugar control. Normal is below 5.7%, pre-diabetes is 5.7-6.4%, and diabetes is 6.5% or higher.
How is eAG calculated from A1C?
The American Diabetes Association formula is: eAG (mg/dL) = (28.7 × A1C%) − 46.7. To convert to mmol/L, divide by 18.018. This formula was derived from a large clinical study correlating continuous glucose monitoring with A1C values.
What is a good A1C level for diabetics?
The ADA recommends an A1C below 7% for most adults with diabetes. Some individuals may have a target of below 6.5% (tighter control) or up to 8% (if hypoglycemia is a concern). Your healthcare provider sets your personal target based on age, complications, and other factors.
How often should I get an A1C test?
For people with well-controlled diabetes, twice per year is typical. For those with poorly controlled diabetes or recent treatment changes, quarterly testing is recommended. For diabetes screening in at-risk adults, testing every 3 years is common.