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A1C Calculator Convert HbA1c to Average Blood Sugar (eAG) and Back

Enter your A1C to see your estimated average glucose in mg/dL and mmol/L, or start from your average glucose to estimate A1C. This free A1C calculator also shows where your result sits on the normal, prediabetes and diabetes ranges.

  • ADAG eAG formula
  • %, mmol/mol, mg/dL, mmol/L
  • Nothing leaves your device

A1C calculator

Convert
A1C unit
4%14%

A1C reflects your average blood sugar over roughly the past two to three months. Enter the value from your lab report.

Estimated average glucoseDiabetes range
154mg/dLThat is about 8.6 mmol/L on average.

NormalPrediabetesDiabetes

A1C (NGSP)
7.0%
A1C (IFCC)
53mmol/mol
Average glucose
154mg/dL
Average glucose
8.6mmol/L

This is in the diabetes range (6.5% or higher). A diagnosis must be confirmed by a doctor, usually with a repeat test. For many adults with diabetes a common goal is below 7%, but your own target may differ.

My A1C log

Saved only in this browser

Add two or more results to see your A1C trend over time.

    Features

    A clearer way to read your A1C

    Lab reports give you a single number. This calculator turns it into an everyday blood sugar figure, places it on a simple range, and lets you follow it over time.

    Works both ways

    Convert A1C to estimated average glucose, or start from your meter or CGM average to estimate A1C.

    Every common unit

    Use A1C in % or mmol/mol and glucose in mg/dL or mmol/L, so it works with lab reports from any country.

    Clear range gauge

    See instantly whether a result falls in the normal, prediabetes or diabetes range used by the American Diabetes Association.

    CGM-friendly GMI

    Using a continuous glucose monitor? Enter your average glucose to get both the ADAG estimate and the GMI.

    Personal trend log

    Record each lab result with its date and watch your trend on a chart, with the change since your last test.

    Private by design

    All calculations and your log stay in your browser. There is no account, no upload and no tracking of your results.

    How to use

    How to use the A1C calculator

    1. Pick a direction

      Choose A1C to blood sugar, or blood sugar to A1C if you know your average glucose.

    2. Match your units

      Select % or mmol/mol for A1C, and mg/dL or mmol/L for glucose, as shown on your report.

    3. Enter your number

      Type it, use the + and − buttons, or drag the slider. Results update instantly.

    4. Read and save

      Check the range gauge and explanation, then add the result to your log to track it.

    Chart

    A1C chart: A1C to average blood sugar

    Estimated average glucose for common A1C values, calculated with the ADAG formula. The row closest to your current result is highlighted.

    A1C (%)A1C (mmol/mol)eAG (mg/dL)eAG (mmol/L)Range
    4.0%20683.8Normal
    4.5%26824.6Normal
    5.0%31975.4Normal
    5.5%371116.2Normal
    6.0%421267.0Prediabetes
    6.5%481407.8Diabetes
    7.0%531548.6Diabetes
    7.5%581699.4Diabetes
    8.0%6418310.2Diabetes
    8.5%6919710.9Diabetes
    9.0%7521211.7Diabetes
    9.5%8022612.5Diabetes
    10.0%8624013.3Diabetes
    10.5%9125514.1Diabetes
    11.0%9726914.9Diabetes
    11.5%10228315.7Diabetes
    12.0%10829816.5Diabetes
    12.5%11331217.3Diabetes
    13.0%11932618.1Diabetes
    13.5%12434118.9Diabetes
    14.0%13035519.7Diabetes
    Ranges

    A1C levels: what your result means

    These are the diagnostic ranges used by the American Diabetes Association. Only a clinician can diagnose diabetes, usually after a repeat or second test.

    Normal

    Below 5.7%

    Below 39 mmol/mol, or an average glucose under about 117 mg/dL (6.5 mmol/L).

    Prediabetes

    5.7% to 6.4%

    39 to 47 mmol/mol. Blood sugar is higher than normal, and lifestyle changes can lower the risk of type 2 diabetes.

    Diabetes

    6.5% or higher

    48 mmol/mol or more, about 140 mg/dL (7.8 mmol/L) average. A doctor confirms the diagnosis.

    Common goal

    Below 7% for many adults

    For many adults with diabetes the ADA suggests below 7% (53 mmol/mol), but targets are set individually.

    Formulas

    How the A1C calculator works

    The conversions use published, widely accepted equations, so you can check every number yourself.

    A1C calculator range gauge showing normal below 5.7%, prediabetes 5.7 to 6.4% and diabetes 6.5% and above
    Example: an A1C of 7%28.7 × 7 − 46.7 = 154 mg/dL, which is about 8.6 mmol/L. In IFCC units the same result is (7 − 2.15) × 10.929 = 53 mmol/mol.

    A1C to eAG (mg/dL)

    The ADAG study formula links A1C to average glucose measured over three months.

    eAG = 28.7 × A1C − 46.7

    mg/dL to mmol/L

    Glucose in mmol/L is the mg/dL value divided by 18, based on glucose's molar mass.

    mmol/L = mg/dL ÷ 18.016

    % to mmol/mol (IFCC)

    Many countries report A1C in mmol/mol. This master equation converts between the two.

    mmol/mol = (A1C − 2.15) × 10.929

    GMI from CGM data

    The glucose management indicator estimates A1C from a CGM's mean glucose, usually over 14 days or more.

    GMI = 3.31 + 0.02392 × mg/dL
    Accuracy

    What can affect an A1C result

    A1C depends on how long red blood cells live, so anything that changes that can make it read higher or lower than your true average.

    • Anaemia and iron levels

      Iron deficiency can raise A1C, while some other anaemias can lower it.

    • Blood loss or transfusion

      Recent bleeding or a transfusion adds younger red cells and can lower the result.

    • Haemoglobin variants

      Traits such as sickle cell can interfere with some A1C test methods.

    • Pregnancy

      Red blood cell turnover changes in pregnancy, so A1C is often lower than expected.

    • Kidney or liver disease

      Advanced kidney or liver conditions can shift A1C away from true average glucose.

    • Some medicines

      Certain treatments, including some for HIV and anaemia, can affect the reading.

    FAQ

    A1C calculator FAQ

    What is A1C?

    A1C, also called HbA1c or glycated haemoglobin, measures the percentage of haemoglobin in your red blood cells that has glucose attached. Because red blood cells live for about three months, A1C reflects your average blood sugar over roughly the past two to three months.

    How do you convert A1C to average blood sugar?

    Use the ADAG formula: estimated average glucose (mg/dL) = 28.7 × A1C − 46.7. For example, an A1C of 7% gives 28.7 × 7 − 46.7 ≈ 154 mg/dL, which is about 8.6 mmol/L.

    What is a normal A1C level?

    For people without diabetes, a normal A1C is below 5.7% (39 mmol/mol). A result from 5.7% to 6.4% is in the prediabetes range, and 6.5% or higher is in the diabetes range, according to the American Diabetes Association.

    What A1C should people with diabetes aim for?

    For many adults with diabetes, the American Diabetes Association suggests an A1C below 7% (53 mmol/mol). Targets can be higher or lower depending on age, other health conditions and the risk of low blood sugar, so agree on yours with your care team.

    What is the difference between A1C and GMI?

    A1C is a lab blood test. GMI, the glucose management indicator, estimates A1C from the average glucose recorded by a continuous glucose monitor using GMI (%) = 3.31 + 0.02392 × mean glucose in mg/dL. The two often differ by a few tenths of a percent.

    How do I convert A1C from percent to mmol/mol?

    Subtract 2.15 from the percentage and multiply by 10.929. For example, 7% becomes (7 − 2.15) × 10.929 ≈ 53 mmol/mol, and 6.5% becomes about 48 mmol/mol.

    Can this A1C calculator diagnose diabetes?

    No. It converts and explains numbers for information only. Diabetes is diagnosed by a clinician using lab tests, usually confirmed with a repeat test, so always discuss your results with a doctor.

    Why does my A1C not match my glucose meter readings?

    Finger-stick readings capture single moments, while A1C reflects a three-month average. Conditions that change red blood cell lifespan, such as anaemia, recent blood loss, pregnancy, kidney disease or haemoglobin variants, can also make A1C read higher or lower than your true average.

    This calculator is for information and education only. It is not a diagnosis or medical advice. Always discuss your results and targets with a doctor or diabetes care team. For more background, see the CDC diabetes resources.

    Understand your numbers with confidence

    Use the A1C calculator whenever you get new lab results, keep a private log of your trend, and bring better questions to your next appointment. For more health tools, explore our free online tools.

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