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A1C Calculator — A1C to Average Glucose (eAG) Converter

Convert A1C to estimated average glucose (eAG) in mg/dL or mmol/L, or IFCC mmol/mol. Bidirectional conversion with ADA normal/prediabetes/diabetes ranges.

Diabetes range
7.0% A1C
Estimated Avg. Glucose
154 mg/dL
Estimated Avg. Glucose
8.6 mmol/L
IFCC Units
53 mmol/mol

eAG uses the ADAG study formula (eAG mg/dL = 28.7 × A1C − 46.7). IFCC units use the NGSP/IFCC master equation. This tool estimates the relationship between A1C and average glucose — it is not a diagnosis. A1C can be affected by anemia, hemoglobin variants, pregnancy, and kidney or liver disease. Confirm any diabetes or prediabetes result with a healthcare provider and a lab-drawn test.
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Reference Values

Last verified:
Category Range What It Means Status
Normal ★ Below 5.7% (eAG below 117 mg/dL) No indication of diabetes or prediabetes based on A1C alone. Routine re-screening intervals depend on individual risk factors. ★ Best
Prediabetes 5.7% – 6.4% (eAG 117–137 mg/dL) Elevated risk of developing type 2 diabetes. The ADA recommends lifestyle intervention and re-testing at least annually. Okay
Diabetes 6.5% or higher (eAG 154+ mg/dL) Meets the ADA diagnostic threshold for diabetes when confirmed by a repeat test (unless symptoms plus a random glucose ≥200 mg/dL are already present). Poor
Typical treatment target (adults with diabetes) Below 7.0% (eAG below 154 mg/dL) The ADA's general A1C target for most non-pregnant adults with diabetes. Individual targets vary — older adults or those with hypoglycemia risk may have a higher target; some are managed to below 6.5%. Good

Source: American Diabetes Association Standards of Care; NGSP/ADAG A1C-to-eAG correlation study (Nathan et al., Diabetes Care 2008)

Worked Examples

A1C 7.0% — Typical Diabetes Management Target

A1C
7.0%
eAG 154.2 mg/dL (8.56 mmol/L) · IFCC 53.0 mmol/mol

28.7 × 7.0 − 46.7 = 154.2 mg/dL. This is the ADA's commonly cited general target for adults with diabetes, though individual targets vary.

A1C 5.5% — Normal Range

A1C
5.5%
eAG 111.1 mg/dL (6.17 mmol/L) · IFCC 36.6 mmol/mol

28.7 × 5.5 − 46.7 = 111.1 mg/dL. Below the 5.7% prediabetes threshold.

A1C 6.0% — Prediabetes Range

A1C
6.0%
eAG 125.5 mg/dL (6.97 mmol/L) · IFCC 42.1 mmol/mol

28.7 × 6.0 − 46.7 = 125.5 mg/dL. Falls in the 5.7%–6.4% prediabetes range — ADA recommends annual re-testing and lifestyle intervention.

Reverse: Average Glucose 170 mg/dL → A1C

Average Glucose
170 mg/dL
A1C ≈ 7.55%

(170 + 46.7) / 28.7 = 7.55%. Useful when you have a CGM or meter average and want an estimated lab A1C equivalent — not a substitute for an actual lab draw.

How to Use This Calculator

  1. 1

    Choose what value you're starting from

    Select A1C percentage, average glucose in mg/dL, average glucose in mmol/L, or IFCC mmol/mol — whichever value you already have.

  2. 2

    Enter the value

    Type in your known number. The calculator validates it against a realistic physiological range.

  3. 3

    Read all converted formats at once

    The result shows A1C%, estimated average glucose in both mg/dL and mmol/L, and IFCC mmol/mol simultaneously, along with the ADA category (normal, prediabetes, or diabetes range).

What Each Value Means

A1C (HbA1c) (percent (%))
A blood test measuring the percentage of hemoglobin that is glycated (bound to glucose), reflecting average blood glucose over the prior 2–3 months. Reported as a percentage in the US (NGSP/DCCT standard).
Estimated Average Glucose (eAG) (mg/dL or mmol/L)
The average blood glucose level that corresponds to a given A1C, calculated from the ADAG study's linear regression formula. Reported in the same units patients see on a home glucose meter (mg/dL in the US, mmol/L in most other countries), making A1C results easier to relate to day-to-day readings.
IFCC (mmol/mol) (mmol/mol)
The International Federation of Clinical Chemistry's HbA1c reporting unit, used as the primary or sole unit in the UK, much of Europe, and other countries. Measures the same glycated hemoglobin as the US percentage format but on a different numeric scale.

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Frequently Asked Questions

How do you convert A1C to estimated average glucose (eAG)?
eAG (mg/dL) = 28.7 × A1C − 46.7. This formula comes from the ADAG (A1C-Derived Average Glucose) study published in Diabetes Care in 2008, and is the formula the American Diabetes Association and NGSP use to report eAG alongside A1C results. For example, an A1C of 7.0% converts to 28.7 × 7.0 − 46.7 = 154.2 mg/dL.
How do you convert average glucose back to an estimated A1C?
A1C (%) = (eAG in mg/dL + 46.7) / 28.7. This is the reverse of the standard ADAG formula and is commonly used to estimate what a lab A1C might read based on a continuous glucose monitor (CGM) or meter average — it is an estimate, not a substitute for an actual lab-drawn A1C test.
What are the A1C ranges for normal, prediabetes, and diabetes?
According to the American Diabetes Association: below 5.7% is normal, 5.7%–6.4% is prediabetes, and 6.5% or higher is diabetes (confirmed by a repeat test on a separate day, unless clear symptoms plus a random glucose of 200 mg/dL or higher are already present). A typical general treatment target for adults already diagnosed with diabetes is below 7.0%, though individual targets vary by age, health status, and hypoglycemia risk.
What is IFCC and how does it relate to A1C percentage?
IFCC (International Federation of Clinical Chemistry) reports HbA1c in mmol/mol rather than the percentage (NGSP/DCCT) format most commonly used in the US. The conversion is IFCC (mmol/mol) = (A1C% − 2.15) × 10.929. Many countries outside the US, including the UK, report HbA1c in IFCC units — this calculator converts between all three formats (A1C%, eAG, and IFCC) automatically.
Can A1C be inaccurate for some people?
Yes. A1C measures glycated hemoglobin, so anything affecting red blood cells or hemoglobin can skew results — including anemia, certain hemoglobin variants (sickle cell trait, thalassemia), recent blood transfusion, pregnancy, and chronic kidney or liver disease. In these situations, a healthcare provider may rely more on direct glucose measurements (fasting glucose, oral glucose tolerance test, or CGM data) rather than A1C alone.