A1C & Average Glucose Calculator
Convert between A1C (%) and estimated average glucose (eAG). This tool supports both mg/dL and mmol/L.
Educational use only. Always discuss diagnosis and treatment goals with your healthcare professional.
What is A1C?
A1C (also called HbA1c) is a blood test that reflects your average blood sugar over roughly the past 2 to 3 months. Instead of showing a single point-in-time glucose value, A1C provides a longer view of glucose control. That makes it one of the most useful metrics for diabetes screening, diagnosis, and ongoing management.
How this calculator helps
Many people see glucose readings in one format (like fingerstick or CGM averages) but get lab reports in another format (A1C %). This calculator helps bridge that gap:
- A1C to eAG: Understand what your A1C means in day-to-day glucose terms.
- Glucose to A1C: Estimate what your average glucose may correspond to as an A1C value.
- mg/dL and mmol/L support: Useful for both U.S. and international users.
Formulas used
The calculator uses a standard ADAG-based relationship:
- eAG (mg/dL) = (28.7 × A1C) − 46.7
- A1C (%) = (eAG + 46.7) ÷ 28.7
- mmol/L = mg/dL ÷ 18
These are estimates. Real-world values vary based on red blood cell turnover, lab method differences, and individual physiology.
A1C range interpretation
| A1C (%) | General Interpretation |
|---|---|
| Below 5.7% | Typical non-diabetes range |
| 5.7% to 6.4% | Prediabetes range |
| 6.5% and above | Diabetes range (diagnostic threshold) |
For many adults with diabetes, a common treatment goal is around below 7.0%, but targets should always be individualized. Age, comorbidities, hypoglycemia risk, pregnancy, and treatment burden all matter.
How to use the calculator
Option 1: Convert A1C to glucose
- Select A1C (%) → eAG (glucose).
- Enter your A1C value (for example, 6.8).
- Click Calculate to see estimated average glucose in mg/dL and mmol/L.
Option 2: Convert glucose to A1C
- Select Average glucose → A1C (%).
- Enter your average glucose value.
- Choose the correct unit (mg/dL or mmol/L).
- Click Calculate to estimate A1C and interpretation category.
Practical tips for improving A1C
- Track fasting and post-meal patterns, not just isolated readings.
- Focus on consistency in carbohydrate intake and meal timing.
- Prioritize sleep quality and stress management.
- Use movement after meals to reduce glucose spikes.
- Review medications regularly with your clinician.
- Use CGM trends, if available, to make smarter adjustments.
Important limitations
A1C is valuable, but it is not perfect. Certain conditions can make A1C less reliable, such as anemia, recent blood loss, hemoglobin variants, kidney disease, pregnancy, and recent transfusion. In these cases, your clinician may use alternatives like CGM time-in-range, fructosamine, or closer fingerstick monitoring.
Bottom line
A good A1C calculator can help you translate numbers into actionable meaning. Use it as a planning and education tool, then confirm your strategy with your healthcare team. Better understanding often leads to better daily decisions—and better long-term outcomes.