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A1C Calculator 2026 — A1C to eAG and eAG to A1C Converter

Convert A1C % to estimated average glucose (eAG) in mg/dL or mmol/L, or convert a blood sugar reading back to an estimated A1C. Includes pre-diabetic risk ranges and CGM context.

For informational purposes only. This tool does not diagnose or treat diabetes. Always consult a qualified healthcare professional for medical advice and blood sugar management.
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eAG (mg/dL)
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eAG (mmol/L)
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Estimated A1C
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Clinical Range
A1C (%)eAG (mg/dL)eAG (mmol/L)Classification
Below 5.7%Below 117Below 6.5Normal
5.7% – 6.4%117 – 1376.5 – 7.6Pre-diabetes
6.5% and above140 and above7.8 and aboveDiabetes

How the A1C Converter Works

  1. A1C to eAG: Uses the ADA formula — eAG (mg/dL) = (28.7 × A1C) − 46.7. Converts to mmol/L by dividing by 18.015.
  2. eAG to A1C: Rearranges the formula — A1C = (eAG + 46.7) / 28.7. Syncs mg/dL and mmol/L fields as you type.
  3. Risk ranges: Based on American Diabetes Association (ADA) 2025 Standards of Care: Normal <5.7%, Pre-diabetes 5.7–6.4%, Diabetes ≥6.5%.
This converter uses the ADA formula — eAG (mg/dL) = (28.7 × A1C) − 46.7 — to translate your HbA1c percentage into estimated average glucose and vice versa, with normal, pre-diabetic (5.7–6.4%), and diabetic (≥6.5%) reference ranges shown automatically.

eAG to A1C — Convert Blood Sugar Readings Back to A1C

The eAG to A1C reverse conversion is useful when you have an average blood sugar reading from your CGM or finger-prick log and want to estimate the corresponding A1C. The formula is: A1C (%) = (eAG + 46.7) ÷ 28.7, where eAG is in mg/dL.

Examples: an eAG of 154 mg/dL gives an estimated A1C of roughly 7.0%; an eAG of 183 mg/dL corresponds to approximately 8.0%; an eAG of 126 mg/dL suggests an A1C of about 6.0%. Use the eAG input field in the calculator above to run this conversion automatically.

eAG (mg/dL)eAG (mmol/L)Estimated A1CRange
975.45.0%Normal
1176.55.7%Pre-diabetes threshold
1377.66.4%Top of pre-diabetes
1548.67.0%Diabetes (managed)
18310.28.0%Diabetes (elevated)

This eAG to A1C conversion is especially helpful for CGM users (Dexcom Stelo, Abbott Lingo, Freestyle Libre) who want to understand their sensor averages in the same units their doctor uses. If your eAG is in mmol/L, multiply by 18.015 first to get mg/dL before applying the formula.

A1C and Blood Sugar: What the Numbers Mean

The HbA1c test (commonly called just "A1C") measures the percentage of haemoglobin in your blood that has glucose attached to it. Because red blood cells live for about 2–3 months, the test reflects your average blood sugar over that period — giving a much more reliable picture than a single fasting glucose reading.

For informational purposes only. A1C is a screening and management tool, not a standalone diagnosis. Always consult a qualified healthcare professional for medical advice, diagnosis, or treatment.

The Rise of Consumer CGMs

Continuous glucose monitors (CGMs) were once available only for people with diabetes by prescription. In 2024, the FDA cleared the first OTC devices — the Dexcom Stelo and Abbott Lingo — for adults without diabetes. These wearable sensors read blood sugar every few minutes for up to 15 days, enabling wellness-focused users to see how meals, exercise, sleep, and stress affect glucose levels in real time. The estimated average glucose (eAG) bridges CGM readings and A1C: it expresses your A1C as a number your CGM can relate to.

Pre-Diabetes: The Window for Intervention

An A1C of 5.7%–6.4% (eAG 117–137 mg/dL) indicates pre-diabetes — a state where blood sugar is elevated but not yet high enough for a diabetes diagnosis. Lifestyle changes (diet improvements, regular aerobic exercise, modest weight loss) can reduce A1C by 0.5%–2% and reverse pre-diabetes in many people. This makes early identification especially valuable.

For metabolic health tracking alongside blood sugar, see our BMI calculator and macro calculator.

Frequently Asked Questions

What is a normal A1C level?
A normal A1C is below 5.7%. Pre-diabetes is diagnosed at 5.7%–6.4%, and diabetes at 6.5% or higher. Most people without diabetes have A1C levels between 4.5% and 5.6%.
How is A1C converted to estimated average glucose (eAG)?
The ADA formula is: eAG (mg/dL) = (28.7 × A1C) − 46.7. For example, an A1C of 7% equals an eAG of about 154 mg/dL (8.6 mmol/L). To convert mg/dL to mmol/L, divide by 18.015.
What is a CGM and how does it relate to A1C?
A CGM (continuous glucose monitor) measures real-time blood sugar every few minutes. Devices like the Dexcom Stelo and Abbott Lingo are now available over the counter for non-diabetics. CGM readings show moment-to-moment glucose, while A1C reflects your 3-month average. The eAG helps bridge the two: it's your A1C expressed as a blood sugar reading your CGM can relate to.
What A1C level requires medication?
The decision to start medication depends on your doctor's clinical assessment, not just the A1C number. Many people with A1C between 6.5% and 8% initially try lifestyle changes (diet, exercise, weight loss) before medication. A1C above 10% is typically treated aggressively with medication. Always consult your doctor or endocrinologist.
Can A1C be inaccurate?
Yes. A1C can be falsely elevated or lowered by conditions that affect red blood cell turnover: hemolytic anemia, iron deficiency anemia, kidney disease, and certain genetic hemoglobin variants. In these cases, your doctor may rely on other glucose measures (fructosamine or continuous glucose monitoring) instead.
How quickly can A1C change?
A1C reflects average glucose over the past 2–3 months (the lifespan of red blood cells). Significant dietary changes or new medication can lower A1C by 0.5%–2% within one testing cycle (3 months). Very rapid changes in the final 4 weeks before the test have the largest impact.
How do I convert eAG (estimated average glucose) back to A1C?
To convert eAG to A1C, use: A1C (%) = (eAG + 46.7) ÷ 28.7, where eAG is in mg/dL. For example, an eAG of 154 mg/dL gives an estimated A1C of about 7.0%. If your eAG is in mmol/L, multiply by 18.015 first to convert to mg/dL. The calculator above handles this eAG to A1C conversion automatically — enter your eAG value in the bottom input field.

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