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A1C Calculator

Convert an A1C result to estimated average glucose (eAG) in mg/dL and mmol/L, or estimate A1C from your average blood sugar, using the ADA formula.

Results

ItemValue
Uses the American Diabetes Association formula eAG = 28.7 × A1C − 46.7. Ranges follow the CDC. This is for information only and is not a diagnosis. Talk to your doctor about your results and targets.

Quick Answer

Estimated average glucose (eAG) = 28.7 × A1C − 46.7. An A1C of 7% equals an average glucose of about 154 mg/dL (8.6 mmol/L). The CDC says an A1C below 5.7% is normal, 5.7% to 6.4% is prediabetes, and 6.5% or above is diabetes.

Last updated: 2 November 2026 ·How we calculate this: the ADA eAG formula

Table of Contents

How This A1C Calculator Works

Choose what you want to convert, and enter your A1C or your average blood glucose. The calculator uses the formula from the American Diabetes Association, based on the A1C-Derived Average Glucose (ADAG) study, to convert between them. It also shows the matching CDC range.

Quick explanation: A1C shows your average blood sugar over about the past 2 to 3 months.

  • A1C: the percent of hemoglobin with sugar attached.
  • eAG: the same result as an average glucose number, like a meter reading.
  • mg/dL and mmol/L: two units for glucose. Divide mg/dL by 18 for mmol/L.

How to Use the A1C Calculator

  1. Choose to convert A1C to glucose, or glucose to A1C.
  2. Enter your A1C percent, or your average glucose in mg/dL or mmol/L.
  3. Press Calculate.
  4. Read the converted value in both glucose units.
  5. See which CDC range the result falls in, and discuss it with your doctor.

Core Formulas

  • eAG (mg/dL): 28.7 × A1C − 46.7
  • A1C from eAG: (eAG + 46.7) ÷ 28.7
  • mg/dL to mmol/L: mg/dL ÷ 18.0

Key Terms

  • A1C: a blood test showing the percent of hemoglobin coated with sugar, reflecting about 2 to 3 months.
  • eAG: estimated average glucose, the A1C shown in glucose units.
  • Prediabetes: blood sugar higher than normal but not in the diabetes range.
  • mg/dL: milligrams per deciliter, the US unit for blood glucose.
  • mmol/L: millimoles per liter, the unit used in many other countries.

Worked Example

Your A1C test result is 8%.

  • eAG = 28.7 × 8 − 46.7 = 182.9 mg/dL
  • In mmol/L: 182.9 ÷ 18 = 10.2 mmol/L
  • An A1C of 8% is in the diabetes range

Real-Life Examples

  • Understanding a lab report: an A1C of 6.5% equals about 140 mg/dL.
  • Comparing with a meter or CGM: an average of 154 mg/dL matches an A1C of about 7.0%.
  • Setting goals: lowering A1C from 9% to 7% means an average glucose drop of about 57 mg/dL.
  • Metric readings: an average of 8.6 mmol/L is an A1C of about 7.0%.

A1C vs Fasting Glucose

  • A1C: a 2 to 3-month average. No fasting needed.
  • Fasting glucose: a single reading after not eating for at least 8 hours.
  • eAG vs your meter: your average from finger sticks can differ from eAG, because checks are often taken at certain times of day.

A1C to Average Glucose Chart

A1CeAG (mg/dL)eAG (mmol/L)CDC range
5%975.4Normal
5.5%1116.2Normal
5.7%1176.5Prediabetes range
6%1257.0Prediabetes range
6.5%1407.8Diabetes range
7%1548.6Diabetes range
7.5%1699.4Diabetes range
8%18310.2Diabetes range
8.5%19710.9Diabetes range
9%21211.7Diabetes range
10%24013.3Diabetes range
11%26914.9Diabetes range
12%29816.5Diabetes range

What Can Affect A1C

  • Anemia and blood loss: can make A1C read lower or higher than true.
  • Hemoglobin variants: some inherited types affect certain A1C tests.
  • Kidney and liver disease: can change results.
  • Pregnancy: doctors may use other tests during pregnancy.

Common Mistakes to Avoid

  • Diagnosing yourself. Only a doctor can diagnose diabetes, usually with repeat tests.
  • Mixing units. Check whether your meter shows mg/dL or mmol/L.
  • Expecting meter averages to match exactly. Timing of checks changes the average.
  • Ignoring conditions that affect A1C. Anemia and some hemoglobin types can skew results.
  • Changing medicine on your own. Talk to your care team first.

Frequently Asked Questions

Below 5.7%, according to the CDC.

5.7% to 6.4%.

6.5% or above, usually confirmed with a second test.

About 154 mg/dL, or 8.6 mmol/L.

With the ADA formula: eAG = 28.7 × A1C − 46.7.

It depends on your health. Your doctor will advise, often every 3 to 6 months for people with diabetes.

Many adults with diabetes aim for below 7%, but goals are set individually with your doctor.

Meters show readings at the times you check, while A1C reflects all hours of the day and night.

Yes. Diet, activity, weight loss and medicines can all help, under your doctor's care.

No. A1C does not require fasting.

Higher A1C means higher risk of complications. Very high results need prompt medical advice.

No. It converts numbers for information only.

From the A1C-Derived Average Glucose (ADAG) study, which compared A1C results with frequent glucose readings in hundreds of people with and without diabetes. The ADA uses this formula to report A1C as an average glucose.

Red blood cells live for about 120 days. Sugar attaches to their hemoglobin over that time, so the test reflects the past 2 to 3 months, with recent weeks counting the most.

Multiply mmol/L by about 18. For example, 7.0 mmol/L is about 126 mg/dL. To go the other way, divide mg/dL by 18.

Yes. Enter your CGM average in mg/dL or mmol/L to estimate A1C. Many CGM apps call a similar number the glucose management indicator (GMI), which uses a slightly different formula, so the two may not match exactly.

References & Sources

SourceUsed ForLink
American Diabetes Association, eAG/A1C Conversion Calculator The formula eAG = 28.7 × A1C − 46.7. https://professional.diabetes.org/glucose_calc
CDC, A1C Test for Diabetes and Prediabetes Normal, prediabetes and diabetes ranges. https://www.cdc.gov/diabetes/diabetes-testing/prediabetes-a1c-test.html