An A1C percentage and a daily glucose number speak different dialects. One is a laboratory result shaped by roughly the last two to three months; the other may be a meter or CGM reading from one particular moment. This A1C to eAG calculator translates between them, giving estimated average glucose in both mg/dL and mmol/L.
Translation is the whole job here. The calculator cannot tell you whether a result is safe for you, diagnose diabetes, replace a laboratory report, or choose a treatment target. It gives a number that can make a lab result easier to discuss with a care team. The calculation runs in your browser, so values entered here stay on your device.
A1C and eAG calculator
Convert an A1C percentage to estimated average glucose, or estimate the A1C linked to an eAG value.
What A1C and eAG mean
A1C, also called hemoglobin A1C or HbA1c, measures the percentage of hemoglobin in red blood cells with glucose attached to it. Because red blood cells live for about three months, the result gives a longer view than one finger-stick reading. The CDC describes it as a picture of average glucose over roughly the past three months. A higher percentage generally reflects higher average glucose over that period.
Estimated average glucose, shortened to eAG, converts the A1C percentage into the units commonly shown on glucose meters. In the United States that is usually mg/dL. Many other countries use mmol/L. The word estimated earns its place. eAG is a mathematical estimate based on the A1C result. It is not a new blood sample, a replacement for a glucose log, or proof that every hour of every day looked the same.
A person can have an eAG of 154 mg/dL from an A1C of 7.0%, for example, while still seeing individual readings well below or above 154. Food, activity, illness, sleep, medication timing and the ordinary tides of the day all leave their marks on real-life glucose values. An average smooths those marks out.
How the A1C to eAG conversion works
The American Diabetes Association’s eAG calculator uses this relationship from the A1C-Derived Average Glucose study:
eAG in mg/dL = 28.7 x A1C percentage – 46.7
The calculator then divides the mg/dL value by 18 to show mmol/L. Working backwards, it uses A1C percentage = (eAG in mg/dL + 46.7) / 28.7. The math is useful for checking a number in a report or preparing a question for an appointment. It is not a dosing calculation. Never change insulin, other diabetes medicines, food plans or activity because of a conversion alone.
For an A1C of 7.0%, the formula gives about 154 mg/dL or 8.6 mmol/L. Those are the values in the ADA chart. A1C is usually reported with one decimal place, and eAG is normally rounded for readability. A few tenths in either direction often reflect rounding rather than a meaningful clinical shift. Decimals can look alarmingly authoritative. They are still decimals.
A1C to eAG quick-reference chart
These values are calculated with the ADA formula. They help translate units. They are not personal glucose targets and do not diagnose prediabetes or diabetes.
| A1C | eAG mg/dL | eAG mmol/L |
|---|---|---|
| 5.0% | 97 | 5.4 |
| 5.5% | 111 | 6.2 |
| 6.0% | 125 | 7.0 |
| 6.5% | 140 | 7.8 |
| 7.0% | 154 | 8.6 |
| 7.5% | 169 | 9.4 |
| 8.0% | 183 | 10.2 |
| 8.5% | 197 | 11.0 |
| 9.0% | 212 | 11.8 |
| 9.5% | 226 | 12.6 |
| 10.0% | 240 | 13.4 |
| 11.0% | 269 | 14.9 |
| 12.0% | 298 | 16.5 |
Keep the original result. When you save an eAG calculation, record the A1C percentage, laboratory date and the unit used. A later conversation is clearer when everyone can see the original result instead of an isolated converted number.
Why A1C and daily readings can feel out of sync
A glucose meter answers a narrow question: what was the glucose concentration in this small sample at this moment? A continuous glucose monitor estimates glucose in fluid between cells and may lag behind a rapid change. A1C takes a long view. Those tools overlap, yet they are built for different kinds of questions.
That distinction matters after a frustrating week. A run of high readings during an infection may be very relevant to your care, even though one week will not define a three-month A1C. The reverse also happens. A person may have several reassuring readings at the times they usually test and still have a higher A1C because glucose rises at other times. A carefully kept log adds timing, meals, symptoms, medication changes and activity. That context gives the number somewhere to stand.
The CDC and ADA both recommend discussing individual glucose goals with a care team. Targets vary with diabetes type, pregnancy, age, medication, risk of hypoglycemia, other health conditions and personal priorities. An eAG conversion does not settle those choices. It may make the next conversation less cryptic.
When A1C needs careful interpretation
A1C can be less reliable when red blood cells are affected by something other than typical turnover. The CDC lists severe anemia, kidney failure, liver disease, some hemoglobin disorders such as sickle cell disease or thalassemia, blood loss or transfusion, some medicines, and early or late pregnancy among factors that can falsely raise or lower an A1C result. Let a clinician or laboratory team know if one of these situations applies.
That is also why a surprising mismatch deserves a question rather than a verdict. If your A1C and glucose readings appear far apart, bring the meter or CGM report, testing routine, medication list and any recent illness or transfusion to a visit. A clinician may check technique, look at a different time window, or choose another test. The calculator cannot resolve the discrepancy on its own.
A1C ranges and medical care
For diagnosis in most nonpregnant adults, CDC materials list A1C below 5.7% as the usual reference range, 5.7% to 6.4% as the prediabetes range, and 6.5% or higher as the diabetes range. Diagnosis normally requires appropriate clinical testing and interpretation. Symptoms, a single home reading or a converted eAG should not be used to diagnose diabetes yourself.
For people already living with diabetes, the ADA says an A1C target below 7% is common for many nonpregnant adults, yet personal targets can be higher or lower. A target that suits one person can be unsafe for another, especially where severe lows, pregnancy, advanced complications or other conditions are involved. Follow the plan made with your own care team.
Seek urgent medical help for severe confusion, seizure, fainting, inability to swallow safely, trouble breathing, chest pain, or a person who cannot stay awake. For repeated out-of-range glucose readings, a laboratory result you do not understand, or symptoms such as marked thirst, frequent urination, vomiting, shakiness or sweating, contact a clinician or follow your diabetes care plan. A web calculator is a poor place to wait out an emergency.
Frequently asked questions
What eAG does an A1C of 7% equal?
An A1C of 7.0% converts to about 154 mg/dL or 8.6 mmol/L using the ADA eAG formula. This is an estimated long-term average, not a target or a current glucose reading.
Can eAG replace checking my blood sugar?
No. eAG is calculated from A1C. Home meter or CGM data can show timing, highs, lows and day-to-day patterns that a three-month estimate cannot show.
Why is my eAG different from my meter average?
Your meter may capture only selected times of day, while eAG is derived from A1C. Monitoring frequency, timing, glucose swings and factors that affect A1C can all contribute. Discuss a large or persistent difference with a clinician.
Can I enter HbA1c in mmol/mol?
No. This calculator accepts A1C reported as a percentage. HbA1c values in mmol/mol use a separate conversion and should not be entered as though they were percentages.
Sources reviewed
- American Diabetes Association: Understanding A1C
- American Diabetes Association: eAG/A1C conversion calculator
- NIDDK: The A1C test and diabetes
- CDC: A1C test for diabetes and prediabetes
- CDC: Monitoring your blood sugar
