A1C & Estimated Average Glucose Calculator
Use this calculator to convert between Hemoglobin A1C (%) and estimated average glucose (eAG). You can calculate in either direction.
A1C to eAG
eAG to A1C
What this A1C calculator app does
This app helps you quickly translate lab and glucose values into a format that is easier to understand. Many people see an A1C number (like 7.1%) and wonder what that means in day-to-day glucose terms. Others track blood sugar in mg/dL or mmol/L and want a rough estimate of their A1C. This tool bridges both views.
How the conversion works
The calculator uses the commonly referenced ADAG formula:
- eAG (mg/dL) = 28.7 × A1C − 46.7
- A1C (%) = (eAG + 46.7) ÷ 28.7
- mmol/L = mg/dL ÷ 18
This gives a useful estimate, not a diagnosis by itself. Lab methods, red blood cell turnover, anemia, kidney disease, and some hemoglobin variants can affect A1C interpretation.
Understanding A1C ranges
| A1C Range | General Interpretation |
|---|---|
| Below 5.7% | Typical non-diabetes range |
| 5.7% to 6.4% | Prediabetes range |
| 6.5% or higher | Diabetes range (needs clinical confirmation) |
How to use this app effectively
1) Convert a recent lab A1C result
Enter your A1C and click Calculate from A1C. You’ll instantly see your estimated average glucose in both mg/dL and mmol/L.
2) Estimate A1C from your glucose trend
If you use a CGM or keep a glucose log, enter your average glucose and unit, then click Calculate from Glucose.
3) Track direction over time
Use the same method regularly and compare trends month to month. Consistency matters more than one isolated number.
Example calculations
- A1C 6.0% → eAG about 126 mg/dL (about 7.0 mmol/L)
- A1C 7.0% → eAG about 154 mg/dL (about 8.6 mmol/L)
- Average glucose 180 mg/dL → estimated A1C about 7.9%
Practical ways to improve A1C
- Focus on consistent meals with fiber, protein, and controlled carbohydrate portions.
- Walk after meals to reduce post-meal glucose spikes.
- Sleep 7–9 hours when possible and manage stress.
- Take medications as prescribed and review dose timing with your clinician.
- Check patterns, not just single highs or lows.
FAQ
Is A1C the same as daily blood sugar?
No. A1C estimates your average glucose over roughly 2–3 months. Fingerstick and CGM readings show short-term values that change throughout the day.
How often should I test A1C?
Many people with diabetes check every 3 months when adjusting treatment, and every 6 months when stable. Your clinician may recommend a different schedule.
Why can A1C and CGM average differ?
They measure related but different things. Biological factors and measurement timing can cause differences. Use both in context with your care team.