Free · Clinical measurement relationships

A1C and Estimated Average Glucose

Evaluate the ADAG regression in either direction and convert NGSP percent to IFCC mmol/mol.

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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Use the result with context

Health results are educational estimates, not a diagnosis or treatment recommendation. A qualified clinician can interpret measurements in the context of your health.

Formula and method

A1C of 7% gives estimated average glucose of 154.2 mg/dL.

Estimated glucose (mg/dL) = 28.7 × A1C (%) − 46.7.

Worked example

Enter these known values and leave the other values blank.

Hemoglobin A1c
7 %
Average blood sugar
154.2 mg/dL

Assumptions and limitations

  • The ADAG regression is a population estimate, not a direct glucose measurement. Use stable adult A1C values within the 4–15% modeled range; pregnancy, altered red-cell survival, anemia, hemoglobin variants and recent transfusion can invalidate interpretation. An inverse estimate does not replace a laboratory A1C test.
  • Local arithmetic preserves captured unit controls and supported inverses. Clear the unknown field and enter sufficient independent measurements; a zero denominator cannot identify a unique inverse.

Common questions

How is this result calculated?

Estimated glucose (mg/dL) = 28.7 × A1C (%) − 46.7.

What limits apply to this model?

The ADAG regression is a population estimate, not a direct glucose measurement. Use stable adult A1C values within the 4–15% modeled range; pregnancy, altered red-cell survival, anemia, hemoglobin variants and recent transfusion can invalidate interpretation. An inverse estimate does not replace a laboratory A1C test.

References

Bookify adds independently reviewed bounds: Use A1C between 4 and 15 percent for the ADAG regression.

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