Your lab reports A1C as a percentage. Your meter or sensor speaks mg/dL or mmol/L. This calculator translates between the two: type an A1C to see the estimated average glucose (eAG) it corresponds to, or type an average glucose to see the A1C. It runs in your browser, and nothing you type is sent or stored. It is a general conversion from published equations, not advice for your situation.
A1C to average glucose
- Average glucose
- – mg/dL
- Average glucose
- – mmol/L
- Same A1C, other unit
- – mmol/mol
Average glucose to A1C
- A1C
- – %
- A1C
- – mmol/mol
How the conversion works
The eAG comes from a straight-line fit between A1C and average glucose in a study of 507 adults: 268 with type 1 diabetes, 159 with type 2 and 80 without diabetes [1]. The fit is average glucose in mg/dL = 28.7 × A1C − 46.7, or in mmol/L, 1.59 × A1C − 2.59 [1]. Going the other way is the same equation turned around: A1C = (average glucose in mg/dL + 46.7) ÷ 28.7.
A1C is written in two ways: as a percentage, or in mmol/mol. In 2007 it was recommended that A1C be reported in mmol/mol, and a master equation links the two: A1C in % = 0.09148 × mmol/mol + 2.152 [2]. The calculator turns a percentage into mmol/mol with 10.93 × A1C − 23.5 [2].
We limit the calculator to A1C values from 4% to 14% (68 to 355 mg/dL). That cap is ours, not part of the equation.
What an eAG is, and what it isn’t
The eAG is a way to write an A1C in the same units as a meter [1]. It is calculated from your A1C, not measured from your readings, and it describes the previous three months [1], so it will not match any single daily reading.
It is also an estimate. In the study, the estimated error (a standard deviation) was 13.4, 15.7 and 18.0 mg/dL at an A1C of 6%, 7% and 8%, so one person’s real average can sit some way above or below the eAG [1]. Some situations also make an A1C less representative of average glucose; the HbA1c post covers them. What a number means for you, and any personal target, is a conversation for your care team.
A1C and eAG at a glance
| 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 | 7.7 |
| 7.0 | 53 | 154 | 8.5 |
| 7.5 | 58 | 169 | 9.3 |
| 8.0 | 64 | 183 | 10.1 |
| 8.5 | 69 | 197 | 10.9 |
| 9.0 | 75 | 212 | 11.7 |
| 9.5 | 80 | 226 | 12.5 |
| 10.0 | 86 | 240 | 13.3 |
| 10.5 | 91 | 255 | 14.1 |
| 11.0 | 97 | 269 | 14.9 |
| 11.5 | 102 | 283 | 15.7 |
| 12.0 | 108 | 298 | 16.5 |
Sources
- Nathan DM, et al. Translating the A1C Assay Into Estimated Average Glucose Values. Diabetes Care, 2008;31(8):1473–1478.
- National Glycohemoglobin Standardization Program, IFCC Standardization: IFCC and NGSP.
We made Steadion, an iPhone tracker for people with diabetes or prediabetes. If you log HbA1c lab results in it, you can watch progress toward the goal you set, next to your glucose readings and time in range. Learn more at steadion.fit.