A1C Calculator
With a1c 7 %, a1c comes to 154 mg/dL — average glucose. It is reached in 6 steps, the last of which is 28.7 * 7 - 46.7, and each one is printed on the page with its numbers filled in. The formula is the one published by Nathan et al., not an approximation fitted to it.
A1C converted to estimated average glucose in both units, by the ADAG regression, with the wide individual scatter that regression hides.
Formula and sources checked · How we check
A1C 7
154 mg/dL
Average glucose for the example below. Editing a field recomputes the calculator below; this figure holds the answer the page was loaded with.
It is written into the HTML rather than drawn by a script, so a search engine reading this page without running JavaScript still finds an answer.
- Estimated average glucose
28.7 * 7 - 46.7154.2 mg/dL- The same in mmol/L
154.2 / 18.01828.558 mmol/L- A1C in IFCC units
(7 - 2.15) * 10.92953.006 mmol/mol- Lower end of the 95% interval
(28.7 * 7 - 46.7) - 0.115 * (28.7 * 7 - 46.7)136.467 mg/dL- Upper end of the 95% interval
(28.7 * 7 - 46.7) + 0.115 * (28.7 * 7 - 46.7)171.933 mg/dL- Points above the usual 7% target
7 - 70 %
Ask about this in the chatA1C to Blood Glucose Chart
Worked example
An A1C of 7% works out to an estimated average glucose of 154 mg/dL, or 8.56 mmol/L. The regression came from 507 people, and the 95% interval around that 154 runs from roughly 136 to 172 — the same A1C in two people can mean averages 36 mg/dL apart.
How to work it out yourself
- 1.Multiply the A1C percentage by 28.7 and subtract 46.7. The answer is milligrams per decilitre.
- 2.Divide by 18.0182 for mmol/L, the unit used outside the United States.
- 3.For the IFCC number reported in much of Europe, subtract 2.15 and multiply by 10.929.
- 4.Read the interval, not the point. The regression fits a population, and individuals scatter around it.
A1C to estimated average glucose
| A1C (%) | Average glucose | The same in mmol/L |
|---|---|---|
| 5 | 97 mg/dL | 5.37 mmol/L |
| 6 | 125 mg/dL | 6.97 mmol/L |
| 7 | 154 mg/dL | 8.56 mmol/L |
| 8 | 183 mg/dL | 10.15 mmol/L |
| 9 | 212 mg/dL | 11.74 mmol/L |
| 10 | 240 mg/dL | 13.34 mmol/L |
| 12 | 298 mg/dL | 16.52 mmol/L |
By the ADAG regression, eAG = 28.7 × A1C − 46.7.
The formula
- Estimated average glucose
28.7 * 7 - 46.7 - The same in mmol/L
154.2 / 18.0182 - A1C in IFCC units
(7 - 2.15) * 10.929 - Lower end of the 95% interval
(28.7 * 7 - 46.7) - 0.115 * (28.7 * 7 - 46.7) - Upper end of the 95% interval
(28.7 * 7 - 46.7) + 0.115 * (28.7 * 7 - 46.7) - Points above the usual 7% target
7 - 7
Source: Nathan et al. — Translating the A1C assay into estimated average glucose values, Diabetes Care 2008, CDC — all about your A1C
Questions people actually ask
- What blood sugar is an A1C of 7?
- An estimated average of 154 mg/dL, or 8.56 mmol/L. "Estimated average" is the whole phrase: it is the mean glucose over roughly three months that best fits an A1C of 7 across a population, not a reading you would see on a meter at any particular moment.
- What is the A1C formula?
- eAG in mg/dL = 28.7 × A1C − 46.7, from the ADAG study published in Diabetes Care in 2008. It is a linear regression fitted to 507 participants whose glucose was measured continuously, not a chemical conversion — which is why it comes with a confidence interval rather than an exact answer.
- Why can two people with the same A1C have different average glucose?
- Because A1C measures how much glucose has stuck to haemoglobin, and that depends on how long red cells live as well as how much sugar they met. Anaemia, recent blood loss, pregnancy, kidney disease and some haemoglobin variants all shift the relationship, and the 95% interval around the fitted line is roughly ±11% for that reason.
- What is the difference between DCCT and IFCC units?
- DCCT reports A1C as a percentage — the number used in the US. IFCC reports millimoles of glycated haemoglobin per mole of total, used across much of Europe. 7% DCCT is 53 mmol/mol IFCC. They measure the same thing on different scales; the conversion is above.
- How long does it take for A1C to change?
- About three months to settle, but not evenly: roughly half of an A1C reflects the most recent month, because older red cells are steadily replaced. A month of tight control moves the number well before the full three months have passed.
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