Enter any one value and the other three update instantly: A1C in percent or mmol/mol, and the estimated average glucose (eAG) it corresponds to in mg/dL or mmol/L.
CGM average to GMI
Wearing a CGM? The glucose management indicator (GMI) converts your sensor average into an A1C-style percentage. Enter the average glucose your CGM app reports for the last 14 to 90 days:
Estimated GMI:
The formulas behind this page
- eAG (mg/dL) = 28.7 x A1C - 46.7, from the ADAG study that defined estimated average glucose. Nathan et al., Diabetes Care 2008
- GMI (%) = 3.31 + 0.02392 x mean glucose (mg/dL), from the study that defined the glucose management indicator. Bergenstal et al., Diabetes Care 2018
- IFCC A1C (mmol/mol) = (A1C% - 2.15) x 10.929, the standard conversion between the two A1C reporting systems.
A1C to average glucose table
| A1C (%) | A1C (mmol/mol) | eAG (mg/dL) | eAG (mmol/L) |
|---|---|---|---|
| 5.0 | 31 | 97 | 5.4 |
| 5.5 | 37 | 111 | 6.2 |
| 6.0 | 42 | 126 | 7.0 |
| 6.5 | 48 | 140 | 7.8 |
| 7.0 | 53 | 154 | 8.6 |
| 7.5 | 58 | 169 | 9.4 |
| 8.0 | 64 | 183 | 10.2 |
| 8.5 | 69 | 197 | 10.9 |
| 9.0 | 75 | 212 | 11.8 |
| 10.0 | 86 | 240 | 13.4 |
| 11.0 | 97 | 269 | 14.9 |
| 12.0 | 108 | 298 | 16.5 |
A1C is only part of the picture: two people with the same A1C can have very different days. That is why modern guidelines pair it with time in range, explained in our Time in Range guide. Need to switch a single value between units instead? Use the blood sugar unit converter.
Frequently asked questions
What is estimated average glucose (eAG)?
eAG translates an A1C percentage into the same units your meter or CGM uses. It comes from the ADAG study formula: eAG in mg/dL = 28.7 × A1C - 46.7. For example, an A1C of 7% corresponds to an eAG of about 154 mg/dL (8.6 mmol/L).
What is a good A1C?
The American Diabetes Association suggests an A1C target of below 7% for many non-pregnant adults with diabetes, but the right target is individual and depends on age, overall health and the risk of lows. Always discuss your personal target with your care team.
Why is my GMI different from my lab A1C?
GMI estimates A1C purely from your CGM average glucose, while a lab A1C also reflects how long your red blood cells live and other individual factors. A gap of a few tenths of a percent is common, and both numbers stay useful: GMI reflects the sensor data you can act on day to day, while the lab value is the clinical reference.
What is A1C in mmol/mol?
Many countries report A1C in IFCC units (mmol/mol) instead of percent. The conversion is mmol/mol = (A1C% - 2.15) × 10.929, so 7% equals 53 mmol/mol. The calculator on this page shows both at once.
Can I estimate A1C from my CGM data?
Yes, that is exactly what the glucose management indicator (GMI) does: it converts your CGM average glucose into an A1C-style percentage. Keep in mind it is an estimate, not a lab result. Sugar Sense shows your average glucose and time in range for the same periods, so you always have the underlying numbers too.
More free tools
This tool is for education only. It is not medical advice, it does not replace laboratory testing, and it must never be used for insulin dosing or other treatment decisions. Always work with your healthcare team. See our full medical disclaimer.
