How to Read an A1C-to-Glucose Conversion Chart Accurately
Understanding how an A1C-to-glucose conversion chart works is important for anyone monitoring long-term blood sugar control. Hemoglobin A1C (HbA1c) reports the percentage of glycated hemoglobin and is used clinically to estimate average blood glucose over the previous two to three months. Many patients and clinicians prefer seeing that value expressed as an estimated average glucose (eAG) in familiar units such as mg/dL or mmol/L. A reliable conversion chart bridges the gap between laboratory A1C results and daily glucose readings from fingersticks or continuous glucose monitoring (CGM). Because A1C and point-in-time glucose measurements reflect different biological information, knowing how to read and interpret a conversion chart helps set realistic expectations and supports better communication with your care team.
How does an A1C-to-glucose conversion chart work?
Most modern A1C-to-glucose charts are based on the American Diabetes Association (ADA) equation that relates A1C to estimated average glucose: eAG (mg/dL) = 28.7 × A1C (%) − 46.7. That formula was derived from studies comparing laboratory A1C values with concurrent continuous or frequent self-monitoring glucose data. Converting the eAG to mmol/L is simple: divide mg/dL by 18. The conversion chart condenses that math into an easy lookup so you can quickly see, for example, that an A1C of 7% corresponds roughly to an eAG of 154 mg/dL (8.6 mmol/L). When you use conversion charts, keep in mind they provide an estimate of average glucose — not the highs and lows — and should be combined with self-monitoring patterns for a complete picture.
What does a typical A1C-to-glucose chart look like?
The table below shows common A1C values and their estimated average glucose (eAG) using the ADA formula. This A1C-to-eAG chart is useful when discussing targets with clinicians or translating lab results into the glucose units shown on home meters and CGMs. Note that rounding conventions vary by source, so use the table as a practical guide rather than an exact measurement.
| A1C (%) | Estimated Average Glucose (mg/dL) | Estimated Average Glucose (mmol/L) |
|---|---|---|
| 5.0 | 97 | 5.4 |
| 5.5 | 111 | 6.2 |
| 6.0 | 126 | 7.0 |
| 6.5 | 140 | 7.8 |
| 7.0 | 154 | 8.6 |
| 7.5 | 169 | 9.4 |
| 8.0 | 183 | 10.2 |
| 8.5 | 197 | 10.9 |
| 9.0 | 212 | 11.8 |
| 10.0 | 240 | 13.3 |
How should you use the conversion chart with your daily glucose readings?
Use the A1C conversion chart as a tool to compare long-term average control against the numbers you see on your glucose meter or CGM. If your A1C-derived eAG is significantly different from your meter average, consider factors such as measurement frequency, time-of-day patterns, or unrecorded nocturnal highs or lows. For people using a CGM, the average glucose reported by the device can be directly compared to the eAG; persistent discrepancies warrant discussion with a clinician. Also consider practical steps: if your A1C translates to an eAG above your target, analyze glucose patterns (fasting, post-meal, overnight) and adjust your care plan in consultation with your healthcare team.
What limits the accuracy of A1C-to-glucose conversions?
A1C is influenced by more than blood glucose. Conditions that change red blood cell lifespan—like recent blood loss, hemolytic anemia, certain hemoglobin variants, pregnancy, or kidney disease—can skew A1C results and therefore the eAG estimate. Ethnic differences and laboratory method variation can also affect measured A1C. Furthermore, A1C reflects an average and will not show variability: two patients with the same A1C may have very different day-to-day glucose swings. When interpreting a conversion chart, pair it with self-monitoring data and, when appropriate, alternative tests such as fructosamine that reflect shorter-term control.
Putting A1C and average glucose into practice
Conversion charts are practical reference tools for patients and clinicians to translate lab A1C numbers into the glucose units used at home. They help communicate goals and trends, but they are not a substitute for individualized medical advice. If your A1C and daily readings don’t align or if you have health conditions that affect hemoglobin, ask your care provider about additional testing or alternative monitoring strategies. Regular review of both A1C and self-monitoring data, along with shared decision-making, produces the most useful insights for managing glucose control.
Disclaimer: This article provides general information about A1C and estimated average glucose and is not a substitute for professional medical advice. For personalized diagnosis or treatment, consult a qualified healthcare professional.
This text was generated using a large language model, and select text has been reviewed and moderated for purposes such as readability.
