Convert an A1C percentage to an estimated average glucose (eAG) with the standard linear formula — 28.7 × A1C − 46.7 in mg/dL. Useful for relating lab values to daily readings.
The example
An A1C of 7%.
| A | B | |
|---|---|---|
| 1 | Item | Value |
| 2 | A1C 7% | — |
| 3 | eAG | → 154 mg/dL |
The formula
The formula:
How it works
How it works:
- Enter A1C as a whole number percentage (7, not 0.07) for this formula.
- Multiply by 28.7 and subtract 46.7 for estimated average glucose in mg/dL.
- For mmol/L, divide the mg/dL result by 18.
- Rearrange to go the other way:
(eAG + 46.7) / 28.7gives A1C from average glucose.
Educational use only. These are general Excel formulas for learning spreadsheet techniques — not medical advice or a substitute for clinical judgment, professional guidelines, or verified dosing references. Always confirm calculations against authoritative sources and institutional protocols.
Try it: interactive demo
A1C (%).
Variations
To mmol/L
Divide by 18:
A1C from glucose
Reverse:
Category lookup
Band the A1C:
Pitfalls & errors
A1C as a percent number. Use 7, not 0.07, in this formula.
mg/dL vs mmol/L. Divide by 18 to convert; don’t mix units.
Estimate only. eAG is a population average, not an individual’s exact mean glucose.
Practice workbook
Frequently asked questions
How do I convert A1C to average glucose in Excel?
How do I get mmol/L?
Can I go from glucose back to A1C?
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