Use this calculator to instantly convert any A1C percentage into its corresponding estimated average glucose (eAG) value — in both mg/dL (US) and mmol/L (UK / international) units. The formula is based on the ADAG study published in Diabetes Care, the same formula used by your lab when generating eAG values on your test report.
A1C → Estimated Average Glucose
Formula: eAG (mg/dL) = 28.7 × A1C − 46.7 · From the ADAG study, the same formula your lab uses. This is a population-average estimate; individual results vary.
What Is Estimated Average Glucose (eAG)?
eAG translates the A1C percentage — an abstract number based on hemoglobin glycation — into the unit you actually see on your fingerstick glucose meter (mg/dL in the US, mmol/L elsewhere). It’s the same information expressed in a more intuitive way.
The relationship between A1C and average glucose was established by the ADAG study (A1c-Derived Average Glucose), which used continuous glucose monitoring and frequent fingersticks across hundreds of patients to derive the conversion formula now used by every commercial lab.
A1C-to-eAG Conversion Table
| A1C (%) | eAG (mg/dL) | eAG (mmol/L) | Classification |
|---|---|---|---|
| 5.0 | 97 | 5.4 | Normal |
| 5.7 | 117 | 6.5 | Upper normal / prediabetes border |
| 6.0 | 126 | 7.0 | Prediabetes |
| 6.5 | 140 | 7.8 | Diabetes threshold |
| 7.0 | 154 | 8.5 | ADA target ceiling |
| 8.0 | 183 | 10.2 | Above target |
| 9.0 | 212 | 11.8 | Poor control |
| 10.0 | 240 | 13.4 | Very poor control |
| 12.0 | 298 | 16.5 | Severely uncontrolled |
For complete diagnostic ranges and what each A1C number means in practice, see our full A1C levels chart.
Why Two Different Glucose Numbers?
You’ll occasionally hear people compare their A1C-derived eAG to their actual daily fingerstick averages and find a discrepancy. This is expected. Fingerstick averages can be biased: most people test more in the morning (fasting) or right before meals (often the lowest points of the day), under-sampling the post-meal peaks. eAG from A1C is biology-derived — it captures everything, including the spikes you didn’t test for.
If your fingerstick average is consistently 30+ mg/dL lower than your eAG, you’re probably missing your post-meal peaks. Consider adding a 2-hour-post-meal test once or twice a week, or trying a continuous glucose monitor (CGM) for richer data.
Frequently Asked Questions
What is the formula for converting A1C to eAG?
eAG (mg/dL) = 28.7 × A1C − 46.7. To get mmol/L, divide the mg/dL result by 18. This is the formula used by labs and recommended by the ADA, derived from the ADAG study.
Is eAG the same as my fingerstick average?
Not exactly. eAG is derived from your A1C, which captures every moment of every day including post-meal peaks you don’t test for. Fingerstick averages are usually biased toward fasting/pre-meal lows. A discrepancy of 20-50 mg/dL between them is common.
Why isn’t the conversion exact for everyone?
The formula represents the population average from the ADAG study. Individual factors (red blood cell lifespan variations, hemoglobin variants, kidney disease) can shift the relationship. About 10% of patients have a clinically meaningful “personal” offset from the formula.
Should I use eAG or A1C to track my progress?
Either works — they measure the same biology. eAG is often more intuitive because the numbers match your fingerstick units, but A1C remains the official diagnostic measure used by clinicians.
