HbA1c / eAG Converter
Enter one value below, then click Calculate. The tool converts between HbA1c (%) and estimated average glucose (eAG).
What is HbA1c?
HbA1c (also called A1c, glycated hemoglobin, or hemoglobin A1c) is a blood test that reflects your average blood glucose over roughly the past 2 to 3 months. Unlike a single fingerstick reading, HbA1c gives a longer-term view of glucose trends and is commonly used for diabetes screening, diagnosis, and ongoing management.
This ha1c calculator helps you quickly convert between HbA1c (%) and estimated average glucose (eAG) in both mg/dL and mmol/L, which can make lab numbers easier to understand.
How to use this ha1c calculator
- Type a value in one field only (HbA1c %, eAG mg/dL, or eAG mmol/L).
- Click Calculate.
- Review converted values and a quick interpretation category.
- Click Clear to start over.
Conversion formula used
The calculator uses the ADAG relationship commonly seen in clinical references:
- eAG (mg/dL) = 28.7 × HbA1c − 46.7
- HbA1c (%) = (eAG mg/dL + 46.7) ÷ 28.7
- eAG (mmol/L) = eAG (mg/dL) ÷ 18
Because real biology varies person-to-person, this should be treated as a practical estimate rather than an exact personal prediction.
How to interpret HbA1c levels
| HbA1c (%) | General Interpretation | Estimated Average Glucose (mg/dL) |
|---|---|---|
| Below 5.7% | Typical non-diabetes range | Below about 117 |
| 5.7% to 6.4% | Prediabetes range | About 117 to 137 |
| 6.5% or higher | Diabetes range (diagnostic context needed) | About 140 or higher |
Important context for diabetes management
If you already have diabetes, your personal target may be different from someone else’s. Many adults are advised to target around 7% or lower, but age, medications, risk of hypoglycemia, pregnancy, kidney disease, and other factors can change goals. Always use your clinician’s individualized target.
What can make HbA1c less accurate?
HbA1c is useful, but not perfect. Results can be affected by conditions that alter red blood cells or hemoglobin, such as:
- Anemia (iron deficiency or other types)
- Recent blood loss or transfusion
- Kidney disease or liver disease
- Pregnancy
- Certain hemoglobin variants
In these situations, your healthcare provider may rely more heavily on continuous glucose monitoring (CGM), self-monitoring logs, fructosamine, or other markers.
Practical ways to improve HbA1c over time
- Track glucose trends, not just isolated numbers.
- Take medications consistently and review dosing with your clinician.
- Build meals around protein, fiber, and lower-glycemic carbohydrates.
- Move your body regularly (even short post-meal walks help).
- Sleep adequately and reduce chronic stress where possible.
- Schedule routine follow-up and repeat labs as recommended.
Frequently asked questions
Is HbA1c the same as daily blood sugar?
No. Daily readings show your glucose at specific moments. HbA1c reflects a broader average over about 8 to 12 weeks.
How often should HbA1c be checked?
Many people with stable control test every 6 months, while those adjusting treatment or not at goal may test every 3 months. Follow your care plan.
Can this calculator diagnose diabetes?
No. This tool is educational and for quick conversion. Diagnosis should come from qualified medical professionals using proper clinical criteria.