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A1C Calculator: Estimated Average Glucose in mg/dL and mmol/L

Enter your hemoglobin A1C and get the estimated average glucose it corresponds to, in both mg/dL and mmol/L, using the ADAG study equation that the American Diabetes Association adopted. The result is read against the ADA's published A1C ranges, with the formula, its confidence interval and its limits stated on the page.

  • Calculator
  • About 3 min
  • ADAG equation, Nathan 2008
  • Runs in your browser, nothing is sent
  • Medical review: Medical review pending
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What this calculator works out

Hemoglobin A1C is the share of hemoglobin that has glucose attached, a slow-moving average of blood sugar over roughly the past two to three months. The calculation turns that percentage into the glucose number most people recognize from a meter, and shows the range the ADA uses to read it.

  1. 1

    Estimated average glucose in mg/dL

    The headline number: the average blood glucose that an A1C value corresponds to, from the regression published by the A1C-Derived Average Glucose (ADAG) study. An A1C of 7.0 percent maps to 154 mg/dL, the figure laboratories print next to the A1C on many US reports.

  2. 2

    The same number in mmol/L

    The ADAG study published a second equation in mmol/L for countries that report glucose in SI units. Both are shown, so a reading can be compared with a meter in the US or anywhere else without a separate conversion step.

  3. 3

    Where the value sits on the ADA ranges

    The result band reads the equivalent A1C against the American Diabetes Association's published ranges: below 5.7 percent, 5.7 to 6.4, 6.5 and above, and the under 7 percent goal that applies to many adults who already have diabetes. The band explains what the range means and what to ask for next; it is not a diagnosis.

How this compares with a typical online quiz

FeatureTypical free quizRegenerated.com
Equation named and sourcedSometimesADAG regression, Nathan et al. 2008, Diabetes Care
mg/dL and mmol/L both reportedOne or the otherBoth, from the two published equations
Confidence interval of the estimate explainedRarelyYes, the 95 percent interval from the study is quoted
Limits of A1C stated (anemia, hemoglobin variants, pregnancy)RarelyYes, in the methodology and the FAQ
ADA ranges cited to the current Standards of CareOften unsourcedYes, 2025 Standards of Care, Sections 2 and 6
Answers sent to a serverOftenNever; scored in your browser, counts-only events

Glucose to A1C: the reverse calculation

This page converts A1C to average glucose. To go the other way, rearrange the same equation: A1C in percent equals average glucose in mg/dL plus 46.7, divided by 28.7. In mmol/L it is average glucose plus 2.59, divided by 1.59. A meter average of 154 mg/dL gives (154 + 46.7) / 28.7 = 7.0 percent. A few anchor points: 100 mg/dL is about 5.1 percent, 126 mg/dL is 6.0, 140 mg/dL is 6.5, 183 mg/dL is 8.0, 212 mg/dL is 9.0 and 240 mg/dL is 10.0.

The reverse direction has a catch. The ADAG equation describes the average relationship across a study population; it was not designed to predict one person's next lab A1C from a meter average. A meter sampled at fasting and before meals also misses the after-meal peaks that a continuous monitor captures, so a meter average usually runs lower than the glucose that A1C reflects. Treat a glucose-to-A1C figure as a rough expectation, and let the laboratory A1C be the number of record.

When A1C can mislead

A1C depends on red blood cells living their normal span of around 120 days. Anything that shortens or lengthens that span moves A1C without any change in glucose. Iron deficiency and some other anemias push it up; hemolysis, recent blood loss, a transfusion, erythropoietin treatment and late pregnancy pull it down. Hemoglobin variants such as sickle trait can interfere with particular assay methods, advanced kidney disease and some HIV medicines also shift it, and the ADA advises using plasma glucose criteria instead when any of these apply.

There is also ordinary person-to-person variation. Two people with the same continuous-monitor average can differ by half a percentage point or more in A1C, a gap that seems to be partly inherited. That is why the ADAG study reported a wide confidence interval and why clinicians look at A1C alongside fasting glucose, a glucose tolerance test or a continuous monitor rather than relying on one number.

A1C in mmol/mol (IFCC units)

Outside the US, A1C is often reported in mmol/mol under the IFCC reference system rather than as a percentage. The conversion is linear: IFCC mmol/mol equals 10.93 times the NGSP percentage minus 23.5. So 5.7 percent is 39 mmol/mol, 6.5 percent is 48 mmol/mol and 7.0 percent is 53 mmol/mol. This calculator takes the percentage; divide a mmol/mol result by 10.93 after adding 23.5 to convert it first.

Methodology and sources

The calculator applies the regression from the A1C-Derived Average Glucose (ADAG) study published by Nathan and colleagues in Diabetes Care in 2008: estimated average glucose in mg/dL equals 28.7 times A1C minus 46.7, and in mmol/L equals 1.59 times A1C minus 2.59. The study followed 507 adults at ten centers in the US, Europe and Africa, 268 with type 1 diabetes, 159 with type 2 diabetes and 80 without diabetes, for twelve weeks. Each person wore a continuous glucose monitor for at least two days every four weeks and took seven-point fingerstick profiles on three days a week, giving around 2,700 glucose readings per person to compare with the A1C at the end. The fit was strong (R squared 0.84), the relationship was linear, and it did not differ by age, sex, diabetes type, ethnicity or smoking. The study excluded people with conditions that disturb red-cell turnover, so the equation does not describe them.

How the number is produced: the A1C you enter is multiplied by 28.7 and 46.7 is subtracted. For an A1C of 7.0 percent, 28.7 x 7.0 = 200.9 and 200.9 minus 46.7 = 154.2 mg/dL. The mmol/L figure comes from the second published equation: 1.59 x 7.0 = 11.13, minus 2.59 gives 8.54 mmol/L. The two equations are not exact unit conversions of each other because each was fitted separately, which is why 154.2 divided by 18 (8.57) differs slightly from 8.54. The result is an average with a spread: the study's 95 percent prediction interval at an A1C of 7.0 percent ran from 123 to 185 mg/dL. Your real average glucose most likely lies somewhere inside that interval, not exactly on the headline number.

The result bands use the American Diabetes Association's A1C criteria from the 2025 Standards of Care: below 5.7 percent is the range the ADA calls normal, 5.7 to 6.4 percent is the prediabetes range, and 6.5 percent or higher on a standardized assay, confirmed by a repeat test or a second abnormal measure, meets the ADA's diagnostic criterion for diabetes. For many nonpregnant adults who already have diabetes, the ADA's general glycemic goal is an A1C below 7 percent, individualized up or down for age, hypoglycemia risk and other conditions. The bands translate those cut-offs into average glucose using the same equation; the equivalent thresholds are 117 mg/dL (5.7 percent), 140 mg/dL (6.5 percent) and 183 mg/dL (8.0 percent). Reference ranges differ between laboratories and the ADA criteria assume an NGSP-certified assay.

Medical review: Medical review pending. Last updated .

References

  1. Nathan DM, Kuenen J, Borg R, Zheng H, Schoenfeld D, Heine RJ; A1c-Derived Average Glucose Study Group. Translating the A1C assay into estimated average glucose values. Diabetes Care. 2008;31(8):1473-1478. doi:10.2337/dc08-0545
  2. American Diabetes Association Professional Practice Committee. 2. Diagnosis and classification of diabetes: Standards of Care in Diabetes-2025. Diabetes Care. 2025;48(Suppl 1):S27-S49. doi:10.2337/dc25-S002
  3. American Diabetes Association Professional Practice Committee. 6. Glycemic goals and hypoglycemia: Standards of Care in Diabetes-2025. Diabetes Care. 2025;48(Suppl 1):S128-S145. doi:10.2337/dc25-S006
  4. Hanas R, John G; International HbA1c Consensus Committee. 2010 consensus statement on the worldwide standardization of the hemoglobin A1C measurement. Diabetes Care. 2010;33(8):1903-1904. doi:10.2337/dc10-0953

A1C Calculator: Estimated Average Glucose in mg/dL and mmol/L FAQ

Rearrange the ADAG equation: A1C percent = (average glucose in mg/dL + 46.7) / 28.7. In mmol/L: (average glucose + 2.59) / 1.59. For example, a 90-day meter average of 140 mg/dL gives (140 + 46.7) / 28.7 = 6.5 percent. Quick table: 100 mg/dL is about 5.1 percent, 126 is 6.0, 154 is 7.0, 183 is 8.0, 212 is 9.0, 240 is 10.0, 269 is 11.0 and 298 is 12.0. A meter average usually under-samples after-meal peaks, so the laboratory A1C can come back higher than this arithmetic predicts.

eAG is the A1C result expressed in the same units a glucose meter uses. The ADA introduced it in 2008 after the ADAG study, so that a person comparing their meter readings with a lab report would be looking at one kind of number. It is an estimate of the average over roughly the past two to three months, weighted toward the most recent four to six weeks, not a reading at any single moment.

In the 2025 Standards of Care, below 5.7 percent is the range the ADA calls normal, 5.7 to 6.4 percent is the prediabetes range, and 6.5 percent or above, confirmed, is a diagnostic criterion for diabetes. For many nonpregnant adults who already have diabetes, the general treatment goal is an A1C under 7 percent, individualized by a clinician. In mmol/mol those cut-offs are 39, 48 and 53.

Three reasons are common. A meter sampled at fasting and before meals misses after-meal peaks, so its average runs low. A1C also reflects the whole red-cell lifespan, weighted toward the past month, while a meter average covers only the days you tested. And people differ in how much glucose attaches to hemoglobin at the same average glucose, a gap of half a percentage point or more that the ADAG confidence interval reflects. A continuous glucose monitor closes most of the first gap but not the third.

When red blood cells are not living a normal lifespan. Iron deficiency and some other anemias raise A1C; hemolysis, recent blood loss, transfusion, erythropoietin treatment and the second and third trimesters of pregnancy lower it. Hemoglobin variants such as sickle cell trait can interfere with some assay methods, and advanced kidney disease and certain HIV medicines also shift it. The ADA advises using plasma glucose criteria in these situations. Ask your clinician which applies to you.

Yes. Your answers and the numbers you enter are scored in your browser and are never sent to us. They stay in this browser tab so you can return to your result, and closing the tab clears them. The only thing the page sends us is a counts-only event: which test was started or completed, the result band and the headline number, with no answers, no entered values and no account. There is nothing to sign up for.

Find clinics that run metabolic programs with proper labs

Browse US clinics offering peptide therapy, where GLP-1 and metabolic programs are usually listed. Look for physician oversight, an A1C and fasting insulin repeated on a schedule, and risks explained before anything is prescribed. A listing on Regenerated.com is not an endorsement.

Browse peptide therapy clinics

A listing is not a treatment endorsement. Read each clinic's published checks and talk to your clinician before starting any treatment.

Important: This calculator is educational arithmetic on a number you enter. It converts A1C to an estimated average glucose with a published equation; it does not diagnose diabetes or prediabetes and it is not a treatment recommendation. The ADA criteria require a standardized laboratory assay and, for a diagnosis, confirmation by repeat testing. Only a clinician who knows your history can interpret your result. If your symptoms are severe or sudden, seek urgent medical care.