eAG Calculator
Estimated values are not a direct glucose measurement. HbA1c and measured glucose can differ because of biological variation or medical conditions affecting red blood cells. Do not change medication or treatment based on this estimate alone; discuss results with your healthcare professional.
What Is an eAG Calculator?
An eag calculator estimates your average blood glucose level using a Hemoglobin A1c (HbA1c) test result. It converts an HbA1c percentage into estimated average glucose (eAG), expressed in mg/dL or mmol/L.
HbA1c reflects average blood sugar exposure over approximately the previous two to three months. The calculation helps explain laboratory results using the same glucose units commonly displayed by blood glucose meters. The result is an estimate, not a direct measurement of your blood sugar.
You can also use this Pension Calculator.
How Is Estimated Average Glucose Calculated?
The calculation uses a mathematical relationship between HbA1c and average glucose established by the A1c-Derived Average Glucose (ADAG) study.
eAG Calculator Formula
For glucose in mg/dL:
\[ \text{eAG (mg/dL)}=28.7\times\text{HbA1c}-46.7 \]
For glucose in mmol/L:
\[ \text{eAG (mmol/L)}=\frac{\text{eAG (mg/dL)}}{18.0182} \]
These formulas estimate average glucose from an HbA1c value expressed as a percentage.
Example Calculation
Suppose your HbA1c test result is 7%.
Step 1: Multiply HbA1c by 28.7.
\[ 7\times28.7=200.9 \]
Step 2: Subtract 46.7.
\[ 200.9-46.7=154.2 \]
Step 3: Convert the result into mmol/L.
\[ 154.2\div18.0182\approx8.56 \]
Estimated average glucose for HbA1c of 7%
154.2 mg/dL
Approximately 8.56 mmol/L
This represents an estimated average across the measurement period, not your glucose level at a particular moment.
How to Use the Calculator
The online tool requires only your HbA1c percentage.
- Enter the HbA1c value from your laboratory report.
- Calculate to convert the percentage into average glucose.
- Review the result in mg/dL or mmol/L.
- Compare the estimate with your glucose monitoring records, where available.
You do not need your date of birth to perform this conversion. The formula uses HbA1c rather than age, although age and medical circumstances can influence how a clinician interprets results.
HbA1c to Estimated Average Glucose Chart
The following table shows approximate glucose values calculated using the standard ADAG formula.
| HbA1c (%) | eAG (mg/dL) | eAG (mmol/L) |
|---|---|---|
| 4 | 68 | 3.8 |
| 5 | 97 | 5.4 |
| 5.7 | 117 | 6.5 |
| 6 | 126 | 7.0 |
| 6.5 | 140 | 7.8 |
| 7 | 154 | 8.6 |
| 8 | 183 | 10.2 |
| 9 | 212 | 11.8 |
| 10 | 240 | 13.3 |
| 11 | 269 | 14.9 |
| 12 | 298 | 16.5 |
Values are rounded for readability. Individual glucose patterns may differ considerably from these estimates.
Understanding HbA1c Reference Ranges
HbA1c measures the percentage of hemoglobin with glucose attached to it. Higher percentages generally indicate greater average glucose exposure.
Common diagnostic categories for nonpregnant adults are:
Below 5.7%
Normal range
5.7%–6.4%
Prediabetes range
6.5% or higher
Diabetes range
These categories refer to HbA1c laboratory results, not separate diagnostic ranges for estimated average glucose. Diabetes diagnosis generally requires confirmation when there is no unequivocal hyperglycemia.
Individual treatment targets may differ based on health conditions, pregnancy, medications, and other clinical factors.
Why eAG May Differ From Glucose Meter Readings
An estimated average does not capture every rise or fall in blood sugar. A finger-stick meter shows glucose at one moment, while HbA1c reflects a longer period.
For example, glucose may increase after meals and decrease overnight. Two people can have similar average glucose levels but very different daily patterns.
Several conditions can also affect HbA1c accuracy, including:
- Iron-deficiency anemia and certain other blood disorders.
- Recent blood loss or transfusion.
- Conditions affecting red blood cell lifespan.
- Some hemoglobin variants.
- Advanced kidney disease and certain other medical conditions.
If your HbA1c-based estimate differs significantly from glucose meter or continuous glucose monitor readings, discuss the difference with your healthcare professional.
eAG vs Glucose Management Indicator
Estimated average glucose and glucose management indicator (GMI) are related but different measurements. eAG is calculated from a laboratory HbA1c result. GMI is calculated from average glucose measured by a continuous glucose monitor (CGM).
GMI provides an HbA1c-like percentage based on CGM data. It is not the same as a laboratory HbA1c measurement, and the two values may disagree. When HbA1c is unreliable, healthcare professionals may consider CGM information or alternative laboratory markers such as fructosamine or glycated albumin.
Who Uses This Calculation?
Converting HbA1c into average glucose can help people understand laboratory reports and compare results with everyday glucose measurements.
Common uses include:
- People managing diabetes: Understanding the approximate glucose average represented by an HbA1c result.
- Healthcare professionals: Explaining laboratory results in familiar glucose units.
- Caregivers: Understanding glucose reports when helping someone manage their condition.
- Patients using glucose monitors: Comparing long-term laboratory estimates with recorded glucose patterns.
- Students: Learning the relationship between HbA1c percentages and glucose concentrations.
The conversion is intended to support understanding, not replace clinical assessment or treatment decisions.
Frequently Asked Questions
What does eAG mean in a blood test?
eAG stands for estimated average glucose. It is calculated from HbA1c and represents an approximate average blood sugar level over the previous two to three months.
What is the estimated average glucose for an HbA1c of 6%?
An HbA1c of 6% corresponds to approximately 126 mg/dL, or 7.0 mmol/L, using the ADAG formula.
Can I calculate HbA1c from eAG?
Yes. Rearranging the standard formula gives HbA1c (%) = (eAG in mg/dL + 46.7) ÷ 28.7.
Is eAG the same as fasting blood sugar?
No. Fasting glucose measures blood sugar at a particular time after fasting, while eAG estimates average glucose over a longer period.
Does age affect the eAG formula?
Age is not an input in the standard formula. However, age and individual health circumstances may affect the interpretation of HbA1c results and appropriate glucose targets.
Calculate Your Estimated Average Glucose
Enter your HbA1c percentage in the calculator above to see its estimated equivalent in mg/dL and mmol/L. Use the result alongside laboratory reports and glucose monitoring records. This calculation is for educational purposes and does not diagnose diabetes or replace medical advice.