Works both ways
Convert A1C to estimated average glucose, or start from your meter or CGM average to estimate A1C.
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A1C Calculator Convert HbA1c to Average Blood Sugar (eAG) and Back
Enter your A1C to see your estimated average glucose in mg/dL and mmol/L, or start from your average glucose to estimate A1C. This free A1C calculator also shows where your result sits on the normal, prediabetes and diabetes ranges.
- ADAG eAG formula
- %, mmol/mol, mg/dL, mmol/L
- Nothing leaves your device
A1C calculator
Convert
A1C unit
Glucose unit
4%14%
A1C reflects your average blood sugar over roughly the past two to three months. Enter the value from your lab report.
Estimated average glucoseDiabetes range
154mg/dLThat is about 8.6 mmol/L on average.
NormalPrediabetesDiabetes
- A1C (NGSP)
- 7.0%
- A1C (IFCC)
- 53mmol/mol
- Average glucose
- 154mg/dL
- Average glucose
- 8.6mmol/L
This is in the diabetes range (6.5% or higher). A diagnosis must be confirmed by a doctor, usually with a repeat test. For many adults with diabetes a common goal is below 7%, but your own target may differ.
My A1C log
Saved only in this browserAdd two or more results to see your A1C trend over time.
Features
A clearer way to read your A1C
Lab reports give you a single number. This calculator turns it into an everyday blood sugar figure, places it on a simple range, and lets you follow it over time.
Every common unit
Use A1C in % or mmol/mol and glucose in mg/dL or mmol/L, so it works with lab reports from any country.
Clear range gauge
See instantly whether a result falls in the normal, prediabetes or diabetes range used by the American Diabetes Association.
CGM-friendly GMI
Using a continuous glucose monitor? Enter your average glucose to get both the ADAG estimate and the GMI.
Personal trend log
Record each lab result with its date and watch your trend on a chart, with the change since your last test.
Private by design
All calculations and your log stay in your browser. There is no account, no upload and no tracking of your results.
How to use
How to use the A1C calculator
Pick a direction
Choose A1C to blood sugar, or blood sugar to A1C if you know your average glucose.
Match your units
Select % or mmol/mol for A1C, and mg/dL or mmol/L for glucose, as shown on your report.
Enter your number
Type it, use the + and − buttons, or drag the slider. Results update instantly.
Read and save
Check the range gauge and explanation, then add the result to your log to track it.
Chart
A1C chart: A1C to average blood sugar
Estimated average glucose for common A1C values, calculated with the ADAG formula. The row closest to your current result is highlighted.
| A1C (%) | A1C (mmol/mol) | eAG (mg/dL) | eAG (mmol/L) | Range |
|---|---|---|---|---|
| 4.0% | 20 | 68 | 3.8 | Normal |
| 4.5% | 26 | 82 | 4.6 | Normal |
| 5.0% | 31 | 97 | 5.4 | Normal |
| 5.5% | 37 | 111 | 6.2 | Normal |
| 6.0% | 42 | 126 | 7.0 | Prediabetes |
| 6.5% | 48 | 140 | 7.8 | Diabetes |
| 7.0% | 53 | 154 | 8.6 | Diabetes |
| 7.5% | 58 | 169 | 9.4 | Diabetes |
| 8.0% | 64 | 183 | 10.2 | Diabetes |
| 8.5% | 69 | 197 | 10.9 | Diabetes |
| 9.0% | 75 | 212 | 11.7 | Diabetes |
| 9.5% | 80 | 226 | 12.5 | Diabetes |
| 10.0% | 86 | 240 | 13.3 | Diabetes |
| 10.5% | 91 | 255 | 14.1 | Diabetes |
| 11.0% | 97 | 269 | 14.9 | Diabetes |
| 11.5% | 102 | 283 | 15.7 | Diabetes |
| 12.0% | 108 | 298 | 16.5 | Diabetes |
| 12.5% | 113 | 312 | 17.3 | Diabetes |
| 13.0% | 119 | 326 | 18.1 | Diabetes |
| 13.5% | 124 | 341 | 18.9 | Diabetes |
| 14.0% | 130 | 355 | 19.7 | Diabetes |
Ranges
A1C levels: what your result means
These are the diagnostic ranges used by the American Diabetes Association. Only a clinician can diagnose diabetes, usually after a repeat or second test.
Below 5.7%
Below 39 mmol/mol, or an average glucose under about 117 mg/dL (6.5 mmol/L).
5.7% to 6.4%
39 to 47 mmol/mol. Blood sugar is higher than normal, and lifestyle changes can lower the risk of type 2 diabetes.
6.5% or higher
48 mmol/mol or more, about 140 mg/dL (7.8 mmol/L) average. A doctor confirms the diagnosis.
Below 7% for many adults
For many adults with diabetes the ADA suggests below 7% (53 mmol/mol), but targets are set individually.
Formulas
How the A1C calculator works
The conversions use published, widely accepted equations, so you can check every number yourself.
A1C to eAG (mg/dL)
The ADAG study formula links A1C to average glucose measured over three months.
eAG = 28.7 × A1C − 46.7mg/dL to mmol/L
Glucose in mmol/L is the mg/dL value divided by 18, based on glucose's molar mass.
mmol/L = mg/dL ÷ 18.016% to mmol/mol (IFCC)
Many countries report A1C in mmol/mol. This master equation converts between the two.
mmol/mol = (A1C − 2.15) × 10.929GMI from CGM data
The glucose management indicator estimates A1C from a CGM's mean glucose, usually over 14 days or more.
GMI = 3.31 + 0.02392 × mg/dLAccuracy
What can affect an A1C result
A1C depends on how long red blood cells live, so anything that changes that can make it read higher or lower than your true average.
Anaemia and iron levels
Iron deficiency can raise A1C, while some other anaemias can lower it.
Blood loss or transfusion
Recent bleeding or a transfusion adds younger red cells and can lower the result.
Haemoglobin variants
Traits such as sickle cell can interfere with some A1C test methods.
Pregnancy
Red blood cell turnover changes in pregnancy, so A1C is often lower than expected.
Kidney or liver disease
Advanced kidney or liver conditions can shift A1C away from true average glucose.
Some medicines
Certain treatments, including some for HIV and anaemia, can affect the reading.
FAQ
A1C calculator FAQ
What is A1C?
A1C, also called HbA1c or glycated haemoglobin, measures the percentage of haemoglobin in your red blood cells that has glucose attached. Because red blood cells live for about three months, A1C reflects your average blood sugar over roughly the past two to three months.
How do you convert A1C to average blood sugar?
Use the ADAG formula: estimated average glucose (mg/dL) = 28.7 × A1C − 46.7. For example, an A1C of 7% gives 28.7 × 7 − 46.7 ≈ 154 mg/dL, which is about 8.6 mmol/L.
What is a normal A1C level?
For people without diabetes, a normal A1C is below 5.7% (39 mmol/mol). A result from 5.7% to 6.4% is in the prediabetes range, and 6.5% or higher is in the diabetes range, according to the American Diabetes Association.
What A1C should people with diabetes aim for?
For many adults with diabetes, the American Diabetes Association suggests an A1C below 7% (53 mmol/mol). Targets can be higher or lower depending on age, other health conditions and the risk of low blood sugar, so agree on yours with your care team.
What is the difference between A1C and GMI?
A1C is a lab blood test. GMI, the glucose management indicator, estimates A1C from the average glucose recorded by a continuous glucose monitor using GMI (%) = 3.31 + 0.02392 × mean glucose in mg/dL. The two often differ by a few tenths of a percent.
How do I convert A1C from percent to mmol/mol?
Subtract 2.15 from the percentage and multiply by 10.929. For example, 7% becomes (7 − 2.15) × 10.929 ≈ 53 mmol/mol, and 6.5% becomes about 48 mmol/mol.
Can this A1C calculator diagnose diabetes?
No. It converts and explains numbers for information only. Diabetes is diagnosed by a clinician using lab tests, usually confirmed with a repeat test, so always discuss your results with a doctor.
Why does my A1C not match my glucose meter readings?
Finger-stick readings capture single moments, while A1C reflects a three-month average. Conditions that change red blood cell lifespan, such as anaemia, recent blood loss, pregnancy, kidney disease or haemoglobin variants, can also make A1C read higher or lower than your true average.
This calculator is for information and education only. It is not a diagnosis or medical advice. Always discuss your results and targets with a doctor or diabetes care team. For more background, see the CDC diabetes resources.
Understand your numbers with confidence
Use the A1C calculator whenever you get new lab results, keep a private log of your trend, and bring better questions to your next appointment. For more health tools, explore our free online tools.
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