Blood sugar can be measured in a variety of ways, which often leads to confusion.
A1c measures blood sugar over the last three months by looking at the percentage of hemoglobin saturated with sugar.
A blood glucose test taken at home measures your current blood glucose measured in milligrams per decilitre or millimoles per litre.
Milligrams per decilitre (mg/dl), used in the United States and Europe, measures the concentration of glucose as a ratio of weight to volume.
Millimoles per litre (mmol/l), used in the United Kingdom, measures the concentration of glucose as a ratio of molecules to volume.
A formula is used to convert the A1c score into a blood glucose score you’re used to seeing every day. This is called the estimated Average Glucose (eAG) level.
You can match your A1c to an eAG using the conversion chart below. For example, an A1c of 5.9 is comparable to blood sugar of 123 mg/dl or 6.8 mmol/l.
A1c Conversion Chart
| A1C Score (percentage) | eAG (in mg/dL) | eAG (in mmol/L) |
|---|---|---|
| 4 | 68 | 3.8 |
| 4.1 | 71 | 3.9 |
| 4.2 | 74 | 4.1 |
| 4.3 | 77 | 4.3 |
| 4.4 | 80 | 4.4 |
| 4.5 | 82 | 4.6 |
| 4.6 | 85 | 4.7 |
| 4.7 | 88 | 4.9 |
| 4.8 | 91 | 5.1 |
| 4.9 | 94 | 5.2 |
| 5 | 97 | 5.4 |
| 5.1 | 100 | 5.6 |
| 5.2 | 103 | 5.7 |
| 5.3 | 105 | 5.8 |
| 5.4 | 108 | 6 |
| 5.5 | 111 | 6.2 |
| 5.6 | 114 | 6.3 |
| 5.7 | 117 | 6.5 |
| 5.8 | 120 | 6.7 |
| 5.9 | 123 | 6.8 |
| 6 | 126 | 7 |
| 6.1 | 128 | 7.1 |
| 6.2 | 131 | 7.3 |
| 6.3 | 134 | 7.4 |
| 6.4 | 137 | 7.6 |
| 6.5 | 140 | 7.8 |
| 6.6 | 143 | 7.9 |
| 6.7 | 146 | 8.1 |
| 6.8 | 148 | 8.2 |
| 6.9 | 151 | 8.4 |
| 7 | 154 | 8.6 |
| 7.1 | 157 | 8.7 |
| 7.2 | 160 | 8.9 |
| 7.3 | 163 | 9.1 |
| 7.4 | 166 | 9.2 |
| 7.5 | 169 | 9.4 |
| 7.6 | 171 | 9.5 |
| 7.7 | 174 | 9.7 |
| 7.8 | 177 | 9.8 |
| 7.9 | 180 | 10 |
| 8 | 183 | 10.2 |
| 8.1 | 186 | 10.3 |
| 8.2 | 189 | 10.5 |
| 8.3 | 192 | 10.7 |
| 8.4 | 194 | 10.8 |
| 8.5 | 197 | 10.9 |
| 8.6 | 200 | 11.1 |
| 8.7 | 203 | 11.3 |
| 8.8 | 206 | 11.4 |
| 8.9 | 209 | 11.6 |
| 9 | 212 | 11.8 |
| 9.1 | 214 | 11.9 |
| 9.2 | 217 | 12.1 |
| 9.3 | 220 | 12.2 |
| 9.4 | 223 | 12.4 |
| 9.5 | 226 | 12.6 |
| 9.6 | 229 | 12.7 |
| 9.7 | 232 | 12.9 |
| 9.8 | 235 | 13.1 |
| 9.9 | 237 | 13.2 |
| 10 | 240 | 13.3 |
| 10.1 | 243 | 13.5 |
| 10.2 | 246 | 13.7 |
| 10.3 | 249 | 13.8 |
| 10.4 | 252 | 14 |
| 10.5 | 255 | 14.2 |
| 10.6 | 258 | 14.3 |
| 10.7 | 260 | 14.4 |
| 10.8 | 263 | 14.6 |
| 10.9 | 266 | 14.8 |
| 11 | 269 | 14.9 |
| 11.1 | 272 | 15.1 |
| 11.2 | 275 | 15.3 |
| 11.3 | 278 | 15.4 |
| 11.4 | 280 | 15.6 |
| 11.5 | 283 | 15.7 |
| 11.6 | 286 | 15.9 |
| 11.7 | 289 | 16.1 |
| 11.8 | 292 | 16.2 |
| 11.9 | 295 | 16.4 |
| 12 | 298 | 16.6 |
The exact formula to convert A1C to eAG (mg/dl) is: 28.7 x A1c – 46.7. The formula to converting mg/dl to mmol/l is: mg/dl / 18.