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A1C → eAG — ADAG 2008

Enter one number — your A1C percentage — and get your estimated average glucose in both mg/dL and mmol/L, using the ADAG study formula clinicians use.

Free interactive tool

A1C to Blood Sugar Converter

Enter your HbA1c percentage to see your estimated average glucose (eAG) in both mg/dL and mmol/L.

Normal< 5.7%
Prediabetes5.7–6.4%
Diabetes≥ 6.5%
Rule of thumb+1% ≈ +29 mg/dL

Educational estimate. eAG is a 2–3 month average and can diverge from a single meter reading, especially with anemia, kidney disease, or certain hemoglobin variants. Interpret results with a clinician.

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A1C to average blood sugar chart

Every A1C percentage maps to an estimated average glucose (eAG). The calculator above is exact for any value you type; the chart below covers the common reference points, from optimal through the diabetes range.

A1C 5.0% — 97 mg/dL (5.4 mmol/L)
Optimal
A1C 5.7% — 117 mg/dL (6.5 mmol/L)
Prediabetes starts
A1C 6.0% — 126 mg/dL (7.0 mmol/L)
Prediabetes
A1C 6.5% — 140 mg/dL (7.8 mmol/L)
Diabetes threshold
A1C 7.0% — 154 mg/dL (8.6 mmol/L)
Common treatment target
A1C 8.0% — 183 mg/dL (10.2 mmol/L)
Above target

Why A1C and average glucose tell different stories

A1C measures the fraction of your hemoglobin that has sugar attached to it, which reflects your average glucose over the 2–3 month lifespan of a red blood cell. A fasting glucose reading, by contrast, is a single morning snapshot. eAG bridges the two: it restates A1C in the mg/dL units your meter shows, so a lab result and a home reading finally speak the same language. When the two diverge sharply, it is worth looking at red-blood-cell turnover — anemia and recent blood loss can move A1C on their own.

Frequently asked questions

How do you convert A1C to average blood sugar?
The ADAG study formula is: estimated average glucose (eAG) in mg/dL = 28.7 × A1C − 46.7. To get mmol/L, divide the mg/dL result by 18. For example, an A1C of 5.7% works out to about 117 mg/dL (6.5 mmol/L).
What is estimated average glucose (eAG)?
eAG translates your A1C percentage into the same mg/dL (or mmol/L) units your glucose meter uses. It represents your average blood sugar over the previous 2–3 months — the lifespan of a red blood cell — so it smooths out the day-to-day spikes a single fasting reading can't capture.
What blood sugar is an A1C of 5.7, 6.0, or 6.5?
Using the ADAG formula: 5.7% ≈ 117 mg/dL (6.5 mmol/L), the start of the prediabetes range; 6.0% ≈ 126 mg/dL (7.0 mmol/L); 6.5% ≈ 140 mg/dL (7.8 mmol/L), the diabetes threshold. The calculator above gives the exact number for any A1C you enter.
Why doesn't my eAG match my fasting glucose?
eAG is a 2–3 month average across all hours of the day, while a fasting reading is a single morning snapshot. eAG includes post-meal peaks, so it is usually higher than fasting glucose. A large gap between the two can also point to unusual red-blood-cell turnover (anemia, recent blood loss), which affects A1C independently of glucose.
Does Merios store these numbers?
No. The calculator runs entirely in your browser. Your inputs never leave your device and are not sent to a server.

Reference: Nathan DM, Kuenen J, Borg R, Zheng H, Schoenfeld D, Heine RJ. Translating the A1C assay into estimated average glucose values. Diabetes Care 2008;31(8):1473-1478.

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One A1C is a number. A trend line is a warning — or an all-clear.

Merios converts every A1C you upload to eAG automatically and plots it against your fasting glucose, weight, and sleep — so you can see whether the line is bending the right way.

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