Diabetes Basics
Article
A1C vs Random Blood Sugar: Two Tests, Two Completely Different Jobs
A random glucose reading and an A1C answer different questions. When each is used for diagnosis, and what a single high reading actually proves.
Read articleA1C to estimated average glucose
A1C Calculator: Turn Results into Actionable Daily Decisions
Convert your A1C to estimated average glucose instantly, compare it with CGM patterns, and use the result to plan the next step in care.
A1C conversion tool
Enter your A1C
%
Accepted range: 4.0% to 15.0%
Common values
Your estimated result
eAGEstimated Average Glucose
mg/dL
A1C screening range
Diabetes
This estimate helps compare A1C with daily glucose units. It does not replace a laboratory result or diagnosis.
ADAG Study Standard
Our calculations use the ADAG (A1C-Derived Average Glucose) formula validated by the American Diabetes Association and the EASD. The formula is: **eAG (mg/dL) = 28.7 × A1C − 46.7**.
01
Published Formulas
Each calculator identifies its equation, required input, output unit, and practical limitations.
02
Fast Comparison
Check A1C, eAG, GMI, and Time in Range without jumping between multiple tools.
03
Clear Boundaries
Calculated estimates are separated from laboratory results, diagnosis, and treatment decisions.
Understanding the result
A1C, eAG, GMI, and TIR Are Not the Same Metric
The numbers are related, but each begins with a different source and answers a different question. Keep the metric name and unit attached to every result.
% or mmol/mol
A1C
Laboratory blood test
Longer-term glucose exposure
mg/dL or mmol/L
eAG
Calculated from A1C
A1C expressed as estimated glucose
%
GMI
CGM mean glucose
CGM-derived glucose indicator
% or time/day
Time in Range
CGM readings
Time within stated glucose limits
Calculator directory
Choose the Right A1C Tool
01
Conversion
A1C to Blood Sugar
- Input
- A1C (%)
- Output
- eAG
02
Reverse conversion
Blood Sugar to A1C
- Input
- Average glucose
- Output
- Estimated A1C
03
CGM estimate
GMI Calculator
- Input
- CGM average
- Output
- GMI (%)
04
CGM analysis
Time in Range
- Input
- CGM range data
- Output
- Range summary
05
Unit conversion
A1C to mmol/mol
- Input
- A1C (%)
- Output
- IFCC mmol/mol
| A1C | eAG (mg/dL) | eAG (mmol/L) |
|---|---|---|
| 5.0% | 97 | 5.4 |
| 5.7% | 117 | 6.5 |
| 6.5% | 140 | 7.8 |
| 7.0% | 154 | 8.6 |
| 8.0% | 183 | 10.2 |
Before calculating
Common A1C Calculator Mistakes
Most incorrect results start with the wrong metric or unit—not difficult arithmetic. Check these four points before using an output.
01
A single reading is not an average
Do not enter fasting glucose, a current meter value, or one CGM reading into a field that asks for mean glucose.
02
mmol/mol is not mmol/L
HbA1c uses mmol/mol internationally. Glucose concentration uses mmol/L; the two units cannot be swapped.
03
GMI is not laboratory A1C
GMI comes from CGM mean glucose and may differ from an A1C measured from a blood sample.
04
A screening range is not a personal target
Diagnosis, confirmation, and an individual management goal are separate clinical questions.
Continue with the original data
A1C Reference Resources
Use the chart, testing guide, or methodology page that matches your next question.
Reader feedback
What People Say About the Calculator
Comments shared by people using our A1C conversion tools.
From the A1C learning center
Latest A1C Articles
Common Questions
Everything you need to know about A1C Testing
An A1C calculator converts a laboratory A1C percentage into estimated average glucose (eAG). It helps express a longer-term A1C result in the same mg/dL or mmol/L units commonly used by glucose meters and CGM reports.