Hemoglobin A1c Calculator - A1c to eAG Conversion

The hemoglobin a1c calculator turns a Hemoglobin A1c percent into an estimated average glucose (eAG) in mg/dL and mmol/L, classifies the reading against the American Diabetes Association thresholds, and shows the target A1c range. It also accepts an average glucose value to recover the A1c.

• • Diabetes screening: A person with a new A1c result reads the classification and the eAG in the units the clinic uses.
• • Diabetes management: A person on therapy compares the current A1c with the adult target of below 7%.
• • CGM-to-lab translation: A CGM user who knows a 90-day average recovers the A1c the lab would report.

The conversion uses the ADAG linear regression, and the diagnostic bands follow the ADA Standards of Care 2024. The calculator is informational; it is not a substitute for a clinician's interpretation.

When the A1c reading has come back in the prediabetes band and the next step is a per-meal blood-sugar plan, Glycemic Index Calculator pairs the daily A1c-derived eAG with the per-meal glycemic load that a diet change can move.

The calculator applies the ADAG regression to convert between A1c and estimated average glucose, then maps the resulting A1c to one of the ADA diagnostic bands.

• A1c (%): The lab-reported A1c in NGSP percent. Valid from 3 to 20.
• Average glucose: An optional 90-day average from a meter or CGM.
• Glucose unit: Selects mg/dL (US standard) or mmol/L (SI standard used by most CGM apps).

The hemoglobin a1c calculator uses the ADAG linear regression. According to Nathan and the ADAG Study Group, the regression has a slope of 28.7 mg/dL per 1% A1c and an intercept of -46.7 mg/dL. The SI-unit form is the same regression divided by 18.0182.

According to Nathan et al. - ADAG study (Diabetes Care, 2008), the linear regression between A1c and estimated average glucose is eAG (mg/dL) = 28.7 * A1c (%) - 46.7, with the SI-unit form eAG (mmol/L) = 1.59 * A1c (%) - 2.59.

According to ADA Standards of Care in Diabetes 2024, Section 2 (Diagnosis and Classification), ADA diagnostic thresholds for diabetes (A1c >= 6.5%) and prediabetes (A1c 5.7-6.4%)

When the A1c reading crosses the diabetes threshold and the next conversation is about starting or adjusting insulin, Insulin Dosage Calculator supports the pre-meal and correction-bolus math that often follows the A1c visit.

Four ideas carry the meaning behind an A1c reading.

The boundary at 5.7% is a population risk threshold, not a personal target. A single mid-range reading usually triggers a conversation about lifestyle, and a reading above 6.5% is a strong signal, not a verdict.

Because diabetes and cardiovascular risk travel together, the cholesterol ratio reported on the same lipid panel is the natural second read after the A1c, and Cholesterol Ratio Calculator gives that ratio side by side with the A1c classification.

Use the calculator with a recent A1c lab result, a recent CGM or fingerstick average, or both.

1. 1 Enter the A1c percent from the lab: Type the A1c percent in the first field. If you have a glucose average, leave the A1c blank and enter the glucose value instead.
2. 2 Pick the matching glucose unit: Choose the unit your meter or CGM uses: mg/dL or mmol/L.
3. 3 Read the A1c, the eAG, and the classification: The result panel shows the A1c, the eAG in both units, the ADA classification, and the target A1c range.
4. 4 Compare the classification to the diagnostic band: Match the classification to the diagnostic band and the target A1c range.
5. 5 Decide on the next step: Use the result to plan a follow-up if the reading is at or above the prediabetes band.

When the A1c sits in the prediabetes band and the next step is a daily carbohydrate target for a low-carb or Mediterranean eating pattern, Carbohydrate Calculator provides the gram-per-day range that pairs with the A1c-derived eAG.

An A1c calculator pairs a single percent reading with the three numbers a person has to talk about in a clinic visit. The hemoglobin a1c calculator does this in both directions.

• • Bidirectional: The same form works with an A1c percent or an average glucose value.
• • ADA-aligned classification: The Normal, Prediabetes, and Diabetes bands match the ADA Standards of Care 2024.
• • Target band tied to the classification: The calculator shows the target A1c range for each band.
• • One form, two glucose units: The result shows eAG in mg/dL and in mmol/L.
• • Built on a published regression: The eAG number uses the ADAG linear regression, which ADA cites in Standards of Care.

The calculator does not give medical advice, does not adjust medications, and does not replace confirmatory testing for diabetes.

Because weight and A1c track together in most prediabetes and type 2 diabetes protocols, the A1c visit is often paired with a BMI review, and BMI Calculator provides the BMI band that the A1c classification is compared with.

Several factors shift the A1c reading or the calculator output.

• • The ADAG regression was derived in adults with stable type 1 or type 2 diabetes and is not validated in children, in pregnancy, or in patients on dialysis.
• • A single A1c reading is not enough for a clinical diabetes diagnosis; the ADA requires confirmation with a repeat A1c, a fasting plasma glucose, or an oral glucose tolerance test on a different day.
• • The result is a calculation, not a measurement. A calculator output cannot replicate the laboratory quality control of an actual A1c assay.

According to the NIH NIDDK, the A1c test can be unreliable in iron-deficiency anemia, recent blood loss, and pregnancy.

According to National Institute of Diabetes and Digestive and Kidney Diseases - A1c Test, A1c test limitations related to anemia, blood loss, transfusion, and pregnancy

Because hypertension and diabetes share a treatment plan in most guidelines, the A1c visit is often the same visit that reviews the latest blood pressure reading, and Blood Pressure Calculator provides the classification and target band the A1c visit depends on.