A1c to Average Blood Glucose Calculator
Convert HbA1c percentage to estimated average glucose (eAG) in mg/dL and mmol/L using the ADA-referenced ADAG formula. Also converts eAG back to estimated A1c.
📊 A1c ↔ Average Glucose
Result
A1c Reference Table
| A1c (%) | eAG (mg/dL) | eAG (mmol/L) | ADA Category |
|---|
ADA targets: < 7% for most non-pregnant adults with diabetes; < 6.5% for some individuals; < 8% for older adults or those with hypoglycemia risk.
The ADAG Formula (ADA-Endorsed)
From: Nathan DM et al. "Translating the A1C assay into estimated average glucose values." Diabetes Care. 2008;31(8):1473–1478. The ADAG study validated this formula across 507 participants over 3 months.
What Estimated Average Glucose (eAG) Means
Your HbA1c reflects the percentage of hemoglobin with glucose attached, averaged over the roughly three-month lifespan of your red blood cells. The ADAG formula translates that percentage onto the same scale as your glucose meter — estimated average glucose (eAG) — so an abstract "7.0%" becomes a familiar "154 mg/dL (8.6 mmol/L)."
That makes an A1c result far easier to act on. If your meter or CGM usually reads well below your eAG, your highs — often overnight or after meals — may be pulling the average up more than you realize.
Why Your Meter Average Can Differ From eAG
eAG is a population estimate. Two people with the same A1c can have genuinely different true average glucose because of how their red blood cells turn over. eAG may not match your meter average when:
- Red blood cell lifespan is altered — anemia, recent blood loss, pregnancy, or hemolysis shorten or lengthen cell life and skew A1c.
- You test at biased times — checking mostly before meals understates your true average; eAG reflects the 24-hour picture.
- You have a hemoglobin variant that interferes with the A1c assay.
If your A1c and day-to-day readings consistently disagree, a CGM's glucose management indicator (GMI) and time-in-range may describe your control better than A1c alone.
Converting Average Glucose Back to A1c
This tool also runs the reverse direction (eAG → A1c) using A1c = (eAG + 46.7) ÷ 28.7. If you want the full HbA1c reference with ADA category bands and target guidance in one place, use the dedicated HbA1c Calculator.
Frequently Asked Questions
What is the average blood glucose for an A1c of 7%?
Using the ADA's ADAG formula (eAG = 28.7 × A1c − 46.7), an A1c of 7% equals an estimated average glucose of about 154 mg/dL, or 8.6 mmol/L.
How do you convert A1c to average glucose?
Multiply your A1c by 28.7 and subtract 46.7 to get eAG in mg/dL. For example, 8% → (28.7 × 8) − 46.7 = 183 mg/dL. Divide mg/dL by 18 to get mmol/L.
Is estimated average glucose the same as my meter average?
Not necessarily. eAG is a statistical estimate from A1c. Your true average can differ because of red blood cell turnover, anemia, pregnancy, or when you test mostly at one time of day.
What A1c is considered diabetes?
The ADA diagnoses diabetes at an A1c of 6.5% or higher, prediabetes at 5.7–6.4%, and normal below 5.7%. A diagnosis should be confirmed by a clinician, usually with a repeat test.
Sources
- Nathan DM et al. "Translating the A1C assay into estimated average glucose values." Diabetes Care. 2008;31(8):1473–1478.
- American Diabetes Association. Standards of Medical Care — 2024. Section 6.
Last reviewed: June 2025