For educational purposes only. Consult your doctor for diagnosis and medical advice.
A1C Conversion ToolFree · Instant
Understanding Your A1C
The A1C test is one of the most important tools for managing diabetes and assessing risk. Unlike daily blood glucose readings, A1C gives your healthcare provider a picture of how your blood sugar has been trending over the past 2-3 months, making it a more reliable indicator of long-term control.
This formula was established through the ADA-sponsored ADAG study and is the standard conversion used by the American Diabetes Association, the American College of Endocrinology, and the European Association for the Study of Diabetes.
Who Is This Calculator For?
This tool is for anyone who wants to understand the relationship between daily blood glucose readings and A1C, or who has received a lab result and wants to see it in different units.
People with type 2 diabetes
Track whether your average glucose readings are on target between doctor visits.
Prediabetes patients
Watch how lifestyle changes affect your estimated A1C over time.
Concerned about family history
Understand what your glucose meter readings mean for long-term risk.
Patients before a doctor visit
Convert a lab A1C figure into the same mg/dL units your glucose meter shows.
Caregivers
Help a family member understand their lab results and what the numbers mean practically.
Students and educators
Use the ADA formula directly for coursework or patient education.
When Should You Use It?
When you receive an A1C lab result and want to see what it means in your meter's units
To estimate your A1C from a running average of your daily glucose readings
Before a diabetes check-up to prepare questions for your doctor
When comparing readings after a diet or medication change
To understand a family member's lab result before their next appointment
How to Use the Calculator
Mode 1: Glucose to A1C
1
Select the Glucose → A1C tab
This mode estimates your A1C from your average blood glucose reading.
2
Enter your average blood glucose
Use your average from your glucose meter or continuous glucose monitor over the past 2-3 months. A single reading is less reliable than a true average.
3
Choose your unit
Select mg/dL if you are in the United States. Select mmol/L if you are in Canada, the UK, or most other countries.
4
Read the result
Your estimated A1C percentage and the Normal, Prediabetes, or Diabetes range label appear instantly below.
Mode 2: A1C to eAG
1
Select the A1C → eAG tab
Use this mode when you already have an A1C percentage from a lab test and want to see the equivalent in glucose meter units.
2
Enter your A1C percentage
Type the number exactly as shown on your lab report (e.g. 6.8).
3
Read the eAG
The result shows your estimated average glucose in both mg/dL and mmol/L, along with the A1C range category.
Example Calculations
Example 1: Glucose → A1C
Your glucose monitor shows an average of 154 mg/dL over the past 3 months.
A1C = (154 + 46.7) ÷ 28.7
A1C = 200.7 ÷ 28.7
A1C = 7.0% (Diabetes range)
Example 2: A1C → eAG
Your lab report shows an A1C of 5.5%.
eAG = (28.7 × 5.5) - 46.7
eAG = 157.85 - 46.7
eAG = 111 mg/dL (Normal range)
What Does the Result Mean?
Below 5.7% - Normal
Blood glucose control is healthy. No intervention needed, though annual checks remain important.
5.7% to 6.4% - Prediabetes
Higher than normal but not yet at the diabetes threshold. Diet, exercise, and weight changes can bring this back to the normal range.
6.5% and above - Diabetes range
Consistent with type 2 diabetes when confirmed on two separate tests. Most doctors aim for below 7% in managed diabetes to reduce complication risk.
Common Mistakes to Avoid
!
Using a single glucose reading
A1C reflects your average over 2-3 months. Using one reading gives a misleading result. Use the average from your device's history or CGM report.
!
Entering mmol/L values in mg/dL mode
The units differ by a factor of about 18. If your meter shows 8.5 mmol/L and you enter that in the mg/dL field, the estimated A1C will be far too low. Always match the unit selector to your reading.
!
Treating this as a replacement for a lab test
This calculator estimates A1C from self-monitored glucose. Actual A1C lab tests measure glycated hemoglobin directly and account for factors this calculator cannot, including anemia and certain genetic variants.
!
Confusing A1C with fasting glucose
Fasting glucose is a snapshot. A1C is a 2-3 month average. They measure related but different things. High fasting glucose does not always mean a high A1C and vice versa.
!
Ignoring the range context
A drop from 8.0% to 7.5% is a meaningful improvement even if 7.5% is still in the diabetes range. Use trends over time, not just single data points.
Frequently Asked Questions
A1C (also called HbA1c or glycated hemoglobin) measures the percentage of hemoglobin in your blood that has glucose attached to it. Because red blood cells live about 2–3 months, A1C reflects your average blood sugar over that period. Higher A1C means higher average blood sugar.
Nathan DM et al. (2008) - Translating the A1C Assay into Estimated Average Glucose Values
Published in Diabetes Care, vol. 31, no. 8. This is the source of the ADAG formula used in this calculator: eAG (mg/dL) = 28.7 × A1C - 46.7.
2
American Diabetes Association - Standards of Medical Care in Diabetes (2025)
Source for the diagnostic thresholds: normal below 5.7%, prediabetes 5.7-6.4%, diabetes 6.5% and above.
3
American Diabetes Association - eAG/A1C Conversion Calculator methodology
Confirms the ADA's official endorsement of the ADAG formula for converting between A1C and eAG values.
S
Dr. Sarah Kim, MD
Endocrinologist, 10 years in diabetes care and metabolic medicine
Dr. Kim reviewed the ADA formula implementation, the diagnostic thresholds, and the clinical context used on this page. She practices at an academic medical center and specializes in type 1 and type 2 diabetes management.
Reviewed: March 2025Last updated: April 2025Formula: ADA ADAG 2008
A1C Reference Table
A1C
mg/dL
mmol/L
5%
97
5.4
5.5%
111
6.2
6%
126
7
6.5%
140
7.8
7%
154
8.6
7.5%
169
9.4
8%
183
10.2
9%
212
11.8
10%
240
13.4
Medical Disclaimer
This calculator is for educational purposes only and does not constitute medical advice. Always consult your physician or endocrinologist for diagnosis and treatment decisions.