# eAG Calculator

> Free eAG calculator. Convert your HbA1c to estimated average glucose (mg/dL and mmol/L) using the ADAG study formula. See the ADA diagnostic categories.

*Source: [https://www.health3.app/tools/eag-calculator](https://www.health3.app/tools/eag-calculator)*

Convert your HbA1c into estimated average glucose (eAG), the same mg/dL or mmol/L units shown on a home glucose meter, using the ADAG study formula. This makes your A1c easier to relate to your day-to-day readings. For full bidirectional unit conversion, see the linked HbA1c converter. Informational reference, not a diagnostic test.

 Tracking your HbA1c? **See your glucose trend over time** and get personalized ranges in the Health3 app.

## What eAG Is

Estimated average glucose (eAG) translates your HbA1c, a percentage, into the everyday glucose units you see on a meter or continuous glucose monitor: mg/dL or mmol/L. The point is intuition. An HbA1c of "7.0%" is abstract; an eAG of "154 mg/dL" or "8.6 mmol/L" connects directly to the numbers you check at home.

The conversion comes from the **A1c-Derived Average Glucose (ADAG) study** (Nathan et al., 2008, *Diabetes Care* 31:1473–1478), which used continuous glucose monitoring and frequent fingerstick readings in 507 people across 10 international centres to fit a linear relationship between HbA1c and average glucose.

 **ADAG formulas (Nathan et al., 2008):**
 `eAG (mg/dL) = 28.7 × HbA1c% − 46.7`
 `eAG (mmol/L) = 1.59 × HbA1c% − 2.59`

### HbA1c and ADA Diagnostic Categories

The table pairs HbA1c with its eAG and the American Diabetes Association diagnostic categories. These are **published reference thresholds**; a single abnormal result is usually confirmed before any clinical diagnosis.

| Category (ADA) | HbA1c % | eAG mg/dL | eAG mmol/L |
| --- | --- | --- | --- |
| Normal | Below 5.7 | Below 117 | Below 6.5 |
| Prediabetes | 5.7 – 6.4 | 117 – 137 | 6.5 – 7.6 |
| Diabetes | 6.5 and above | 140 and above | 7.8 and above |

### Why Your Real Average May Differ

- **Individual variation.** eAG is a population average; your personal value can differ by about ±15–20 mg/dL because glycation rates and red-cell lifespan vary.
- **Conditions that affect red cells.** Anaemia, haemoglobinopathies, recent transfusion, chronic kidney disease, and pregnancy can make HbA1c (and therefore eAG) an unreliable mirror of true average glucose.
- **GMI is different.** The Glucose Management Indicator from a CGM uses a different equation and often differs from lab HbA1c in the same person.

### Explore Related Tools and Topics

 [HbA1c to Average Glucose Converter](https://www.health3.app/tools/hba1c-glucose-converter) [HOMA-IR Calculator](https://www.health3.app/tools/homa-ir-calculator) [Blood Glucose](https://www.health3.app/biomarkers/bloodgluco) [Metabolic Health](https://www.health3.app/topics/metabolic-health) [Tracking for Prediabetes](https://www.health3.app/use-cases/blood-test-tracking-for-prediabetes)

## Frequently Asked Questions

 What is eAG (estimated average glucose)? eAG translates your HbA1c into the mg/dL or mmol/L units shown on a glucose meter, so your A1c is easier to relate to daily readings. The formula comes from the ADAG study (Nathan et al., Diabetes Care 2008): eAG (mg/dL) = 28.7 x HbA1c% - 46.7, and eAG (mmol/L) = 1.59 x HbA1c% - 2.59. Is eAG the same as my actual average glucose? Not exactly. eAG is a population-average estimate, so your real average can differ by roughly plus or minus 15 to 20 mg/dL because glycation rates and red-cell lifespan vary between people. It is a useful translation of HbA1c, not a measurement of your specific average. How is eAG different from the GMI on my CGM? The Glucose Management Indicator (GMI) is calculated from continuous glucose monitor data using a different equation, while eAG is derived from HbA1c. The two often differ by 0.5% or more in the same person because they measure related but distinct things. Neither is simply more accurate. Do I need this if I have the HbA1c converter? This tool focuses specifically on turning HbA1c into average glucose. If you also need to convert HbA1c between % (NGSP) and mmol/mol (IFCC), or start from an eAG value, use the HbA1c to Average Glucose Converter, which handles all four values at once. What HbA1c corresponds to a normal average glucose? An HbA1c below 5.7% is the ADA normal category, corresponding to an eAG below about 117 mg/dL (6.5 mmol/L). Prediabetes is 5.7 to 6.4% and diabetes is 6.5% or higher. These are published diagnostic thresholds, and a single result is usually confirmed before any clinical diagnosis. **Medical Disclaimer:** eAG is a statistical estimate from the ADAG study (Nathan DM, et al. *Diabetes Care*. 2008;31(8):1473–1478) and may differ from your true average glucose by about ±15–20 mg/dL. HbA1c can be unreliable in anaemia, haemoglobinopathies, recent transfusion, chronic kidney disease, and pregnancy. The ADA categories shown are published thresholds, not a diagnosis. This tool is for informational and educational use only. Always consult a qualified healthcare provider to interpret your results.