Free HbA1c Unit Converter
Enter one value only (HbA1c %, IFCC mmol/mol, eAG mg/dL, or eAG mmol/L), then click Convert.
Tip: This A1c calculator supports both A1c to mmol/mol conversion and average glucose conversion.
What this HbA1c conversion calculator does
This tool helps you quickly convert between the most common diabetes lab reporting formats: HbA1c percentage (%) used in the U.S., HbA1c mmol/mol used in many other countries, and estimated average glucose (eAG) in both mg/dL and mmol/L.
If you are reading international lab reports, comparing research papers, or trying to understand your own trends over time, having an accurate A1c converter can save a lot of confusion.
HbA1c units explained
1) NGSP/DCCT (%)
This is the familiar U.S. style, where results are shown as a percentage such as 5.7%, 6.5%, or 7.2%.
2) IFCC (mmol/mol)
This is the international standard. A value of 48 mmol/mol is equivalent to about 6.5%. Some countries report only mmol/mol, so conversion is often needed.
3) Estimated Average Glucose (eAG)
eAG translates A1c into a glucose value that looks similar to meter readings: mg/dL (common in U.S.) or mmol/L (common internationally). It is an estimate, not a replacement for daily glucose checks.
Formulas used in this calculator
- IFCC (mmol/mol) = (HbA1c% − 2.15) × 10.929
- HbA1c% = (0.09148 × IFCC) + 2.152
- eAG (mg/dL) = (28.7 × HbA1c%) − 46.7
- eAG (mmol/L) = eAG (mg/dL) ÷ 18
How to use the calculator correctly
- Enter one known value in any single field.
- Leave the other fields blank.
- Click Convert.
- Read all equivalent values and the basic interpretation shown below the calculator.
Quick interpretation guide (HbA1c %)
| HbA1c % | General Category | Approx IFCC (mmol/mol) |
|---|---|---|
| Below 5.7% | Typical non-diabetes range | Below 39 |
| 5.7% to 6.4% | Prediabetes range | 39 to 46 |
| 6.5% and above | Diabetes range (diagnostic threshold) | 48 and above |
Why A1c and daily glucose numbers may not match perfectly
HbA1c reflects average glucose exposure over roughly 2-3 months, while fingerstick or CGM values show current or short-term glucose. Because of this, a person can have "good looking" fasting readings but still have a higher A1c from post-meal spikes.
Factors that can affect HbA1c reliability
- Anemia or recent blood loss
- Hemoglobin variants
- Chronic kidney disease
- Pregnancy (specific trimester-related considerations)
- Conditions changing red blood cell lifespan
Frequently asked questions
Is this calculator accurate?
Yes, it uses widely accepted conversion equations from standard clinical references. Small differences may occur due to rounding in reports.
Can I convert A1c to average blood sugar?
Yes. Enter HbA1c % and this tool gives estimated average glucose in both mg/dL and mmol/L.
What is 6.5% A1c in mmol/mol?
Approximately 48 mmol/mol.
Bottom line
This HbA1c conversion calculator is designed for fast, practical use: A1c percent to mmol/mol, mmol/mol to A1c, and A1c to estimated average glucose. It is ideal for patients, clinicians, researchers, and anyone comparing international diabetes lab results.