---
title: A1c to Estimated Average Glucose (eAG) Calculator
type: tool
url: "https://www.test-well.com/tools/eag-calculator"
date_published: 2026-09-26
free: true
---

# A1c to Estimated Average Glucose (eAG) Calculator

> Enter a hemoglobin A1c in percent or mmol/mol and the calculator returns the estimated average glucose (eAG) in mg/dL and mmol/L using the ADAG study equation, 28.7 × A1c − 46.7. It also places the A1c in the American Diabetes Association categories: under 5.7% normal, 5.7–6.4% prediabetes, 6.5% and above diabetes when confirmed.

## Key facts

| Fact | Value |
| --- | --- |
| Input | A1c % or mmol/mol |
| Equation | ADAG (Nathan 2008) |
| Outputs | mg/dL · mmol/L |
| Cost | Free |

## For agents

See https://www.test-well.com/developers for the agent endpoints.

## Frequently asked questions

### Why does my meter average not match the eAG?

eAG is a population regression from the ADAG study, and glycation rates differ between people, so true mean glucose at a given A1c varies by 20–30 mg/dL either way. Meter averages also skew toward the times you test (often fasting), which are lower than the all-day mean.

### What A1c is normal, prediabetes and diabetes?

The American Diabetes Association uses under 5.7% as normal, 5.7–6.4% as prediabetes and 6.5% or higher as the laboratory criterion for diabetes, confirmed on a second test. For most adults with diabetes the treatment target is under 7%, an eAG of about 154 mg/dL.

### When is A1c unreliable?

Anything that changes red-cell lifespan or hemoglobin: iron-deficiency or hemolytic anemia, hemoglobin variants such as HbS or HbC, recent transfusion, pregnancy, advanced kidney disease and some HIV medications. In those situations fasting glucose or a fructosamine test is used instead.

## Related

- [hemoglobin a1c](https://www.test-well.com/biomarkers/hemoglobin-a1c)
- [glucose](https://www.test-well.com/biomarkers/glucose)
- [fasting insulin](https://www.test-well.com/biomarkers/fasting-insulin)
- [hemoglobin a1c](https://www.test-well.com/tests/hemoglobin-a1c)
- [glucose fasting](https://www.test-well.com/tests/glucose-fasting)
- [diabetes screening panel](https://www.test-well.com/tests/diabetes-screening-panel)
- [general wellness panel](https://www.test-well.com/tests/general-wellness-panel)

---

Canonical page: https://www.test-well.com/tools/eag-calculator
Machine-readable catalog: https://www.test-well.com/api/catalog.json · MCP server: https://www.test-well.com/mcp · Overview for agents: https://www.test-well.com/llms.txt

Prices are cash-pay, in USD, and include physician authorization; every order adds one flat $6 lab processing fee. Educational content is not a diagnosis — discuss results with a clinician.