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    A1C Calculator (HbA1c to Average Glucose)

    Turn your HbA1c into an average blood sugar, or your average into an estimated A1C, in % or mmol/mol, and see which range it falls in.

    More options
    %
    mg/dL

    Type in either box and the other one fills in. Your lab report shows A1C as a % (US and most countries) or in mmol/mol (UK, Ireland, much of Europe).

    %

    Many adults with diabetes aim for below 7% (53 mmol/mol). Your own goal is one to agree with your care team.

    %

    Shows how much it has changed since then.

    Paste glucose readings in mg/dL, separated by commas, spaces or new lines. They are read in the unit chosen above.

    Readings come from
    mg/dL
    mg/dL

    ResultUpdates as you type—A1C in %—A1C in mmol/mol—Average glucose—Average glucoseADA (US) in %—NICE (UK) in mmol/mol—General information, not medical advice. Talk to your doctor about your results.
    A1C chart: % to mmol/mol and average glucose
    A1C %mmol/molmg/dLmmol/LADA (US)NICE (UK)
    4.020683.8NormalNorNormalNor
    4.526824.6NormalNorNormalNor
    5.031975.4NormalNorNormalNor
    5.5371116.2NormalNorNormalNor
    6.0421267.0PrediabetesPrePrediabetesPre
    6.5481407.7DiabetesDiaDiabetesDia
    7.0531548.5DiabetesDiaDiabetesDia
    7.5581699.3DiabetesDiaDiabetesDia
    8.06418310.1DiabetesDiaDiabetesDia
    8.56919710.9DiabetesDiaDiabetesDia
    9.07521211.7DiabetesDiaDiabetesDia
    9.58022612.5DiabetesDiaDiabetesDia
    10.08624013.3DiabetesDiaDiabetesDia
    10.59125514.1DiabetesDiaDiabetesDia
    11.09726914.9DiabetesDiaDiabetesDia
    11.510228315.7DiabetesDiaDiabetesDia
    12.010829816.5DiabetesDiaDiabetesDia
    12.511331217.3DiabetesDiaDiabetesDia
    13.011932618.1DiabetesDiaDiabetesDia
    13.512434118.9DiabetesDiaDiabetesDia
    14.013035519.7DiabetesDiaDiabetesDia

    Average glucose by the ADAG formula. Your result's nearest row is highlighted. Colours: green normal, amber prediabetes, red diabetes.

    How your A1C is worked out

    A1C % ↔ mmol/mol ↔ average glucose, with the ADAG and IFCC formulas.

    1. 1

      Your A1C in %

      You typed 7%= 7.0%

    2. 2

      In mmol/mol

      (7 − 2.15)× 10.929= 53 mmol/mol

    3. 3

      Average glucose

      28.7 × 7 − 46.7(≈ 8.5 mmol/L)= 154 mg/dL

    4. 4

      Which range

      ADA (US) 7.0%→ diabetesNICE (UK) 53→ diabetes

    Read more: the formulas, a worked example, ranges, the chart and when A1C can mislead

    A1C (also called HbA1c or glycated haemoglobin) is a blood test that shows how much sugar has stuck to the haemoglobin in your red blood cells. Red cells live for about three months, so A1C reflects your average blood sugar over the past two to three months, with the most recent weeks counting most. This page turns that number into an estimated average glucose (eAG), converts between the two ways labs report it, and shows which range it falls in. It is general information, not medical advice.

    The formula

    A1C in mmol/mol = (A1C % − 2.15) × 10.929
    A1C % = mmol/mol ÷ 10.929 + 2.15
    Average glucose (mg/dL) = 28.7 × A1C % − 46.7
    Average glucose (mmol/L) = 1.59 × A1C % − 2.59
    Estimated A1C % from an average = (mg/dL + 46.7) ÷ 28.7
    GMI % (sensor data) = 3.31 + 0.02392 × average mg/dL

    Worked example

    An A1C of 7%: in mmol/mol it is (7 − 2.15) × 10.929 = 4.85 × 10.929 = 53.006, so 53 mmol/mol. The estimated average glucose is 28.7 × 7 − 46.7 = 200.9 − 46.7 = 154.2 mg/dL (154), or 1.59 × 7 − 2.59 = 11.13 − 2.59 = 8.54 mmol/L (8.5). That is 6.5% or more, and 48 mmol/mol or more, so it sits in the diabetes range for both the ADA and NICE. For many adults who already have diabetes, 7% is a common treatment goal.

    Going the other way, an average of 154 mg/dL gives (154 + 46.7) ÷ 28.7 = 200.7 ÷ 28.7 = 6.99%, which rounds to 7.0%.

    A1C ranges: US and UK

    RangeADA (US), %NICE / Diabetes UK, mmol/mol
    Normalbelow 5.7below 42
    Prediabetes5.7–6.442–47
    Diabetes6.5 or more48 or more

    The two agree on diabetes (6.5% is 48 mmol/mol) but not on where prediabetes starts. 42 mmol/mol is 6.0%, so 5.7–5.9% (39–41 mmol/mol) is prediabetes in the US and normal in the UK. The WHO also uses 6.5% (48 mmol/mol) for diabetes. One high result is usually repeated before a diagnosis, unless you also have clear symptoms.

    How much the average can vary

    The ADAG formula comes from a 2008 study that compared A1C with continuous and finger-prick glucose in about 500 people. It is an average: people with the same A1C can have quite different glucose levels. The study's 95% ranges:

    A1CAverage glucose95% of people between
    5%97 mg/dL (5.4 mmol/L)76–120 mg/dL
    6%126 mg/dL (7.0 mmol/L)100–152 mg/dL
    7%154 mg/dL (8.5 mmol/L)123–185 mg/dL
    8%183 mg/dL (10.1 mmol/L)147–217 mg/dL
    9%212 mg/dL (11.7 mmol/L)170–249 mg/dL
    10%240 mg/dL (13.3 mmol/L)193–282 mg/dL
    11%269 mg/dL (14.9 mmol/L)217–314 mg/dL
    12%298 mg/dL (16.5 mmol/L)240–347 mg/dL

    Estimating A1C from your readings

    In Advanced mode you can paste your glucose readings. The calculator averages them and gives two estimates. The glucose management indicator (GMI) is made for continuous glucose monitor (CGM) data covering at least 14 days. The ADAG estimate uses the same formula as above, turned around. A handful of finger-prick readings, often taken before meals, can give an average quite different from your true one, so treat it as a rough guide. A GMI and a lab A1C often differ by a few tenths of a percent; that is normal.

    It also shows time in range: the share of readings inside your target range. For most adults with type 1 or type 2 diabetes, an international consensus suggests more than 70% of time between 70 and 180 mg/dL (3.9–10.0 mmol/L), less than 4% below 70 mg/dL and less than 25% above 180 mg/dL. The coefficient of variation (CV = standard deviation ÷ average) shows how much your readings swing; 36% or less is usually seen as stable. Time in range from sensor data is worked out from time, so with readings taken at random times it is only an estimate.

    When A1C can mislead

    • Anaemia, recent blood loss or a blood transfusion, and some haemoglobin variants (such as sickle cell trait) can make A1C read too high or too low.
    • Pregnancy, advanced kidney or liver disease, and some medicines can change it too.
    • A big change in your blood sugar in the last few weeks will only partly show up yet.
    • If your A1C and your home readings don't match, tell your doctor; they may use other tests.

    Sources

    This calculator gives general information, not medical advice, and it can't diagnose diabetes. Only a lab test, usually repeated, can do that. Talk to your doctor or diabetes team about your results and your own A1C goal; goals are often higher for older adults or people prone to low blood sugar, and lower in pregnancy.

    Common questions

    What average blood sugar is an A1C of 7%?

    An A1C of 7% matches an estimated average glucose of about 154 mg/dL, or 8.5 mmol/L, using the ADAG formula: 28.7 × 7 − 46.7 = 154.2 mg/dL. In the UK the same result is written as 53 mmol/mol. People with the same A1C can still have quite different averages: in the ADAG study the middle 95% ranged from about 123 to 185 mg/dL.

    How do I convert A1C % to mmol/mol?

    Take 2.15 away from the percentage and multiply by 10.929. For example, (7 − 2.15) × 10.929 = 53 mmol/mol. To go back, divide by 10.929 and add 2.15: 48 ÷ 10.929 + 2.15 = 6.5%. The UK, Ireland, New Zealand and much of Europe report A1C in mmol/mol; the US and many other countries use %.

    What A1C level means prediabetes or diabetes?

    The American Diabetes Association uses below 5.7% as normal, 5.7% to 6.4% as prediabetes and 6.5% or more as diabetes. NICE and Diabetes UK in the UK use mmol/mol: below 42 is normal, 42 to 47 is prediabetes and 48 or more is diabetes. A diagnosis usually needs a second test, so talk to your doctor about any result.

    Why do the US and UK ranges disagree at 5.7% to 5.9%?

    Prediabetes starts at 5.7% for the ADA but at 42 mmol/mol (6.0%) for NICE. So 5.7%, 5.8% and 5.9% (39 to 41 mmol/mol) count as prediabetes in the US and normal in the UK. Both start diabetes at the same point: 6.5% is 48 mmol/mol.

    Can I work out my A1C from my glucose readings?

    Roughly. Paste your readings into Advanced mode to get the average, then an estimated A1C from the ADAG formula and the glucose management indicator (GMI = 3.31 + 0.02392 × average mg/dL). GMI is meant for at least 14 days of sensor (CGM) data. A few finger-prick readings give a rough guess only, and neither replaces a lab A1C test.

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