A1C Calculator: Convert A1C to Estimated Average Glucose
Our free A1C calculator converts your hemoglobin A1C percentage into an estimated average glucose (eAG) value, and it works in both directions — you can also convert average blood sugar to A1C. Whether you are looking up a single result, estimating your A1C from glucose to A1C, or comparing your numbers to an A1C conversion chart, this A1C to eAG tool uses the validated ADAG formula to give you a result in seconds. It supports both mg/dL and mmol/L, so it works for anyone using a US or international glucose meter.
The A1C test measures how much glucose has attached to your hemoglobin over the past two to three months. Because red blood cells live about 90 days, the A1C percentage is the most reliable long-term snapshot of your blood sugar levels. The A1C to eAG conversion simply translates that percentage into the everyday numbers you see on your glucose meter, making it easier to understand what your A1C means in practice. This A1C to blood sugar conversion is the same approach used by the American Diabetes Association (ADA), and our free A1C calculator mirrors their published formula exactly.
Beyond the basic A1C to glucose conversion, this page doubles as a complete resource: it explains the A1C formula with worked examples, includes both a forward A1C to eAG table and a reverse mg/dL to A1C table, covers the Glucose Management Indicator (GMI) for CGM users, lists normal A1C levels by range, and answers nearly thirty frequently asked questions about A1C, eAG, and blood sugar. Everything on the page uses the same formulas, so the numbers always agree — whether you convert A1C to eAG or glucose to A1C, you get the same clinically validated result.
What Is an A1C Calculator and Why Use One?
An A1C calculator is a tool that converts between hemoglobin A1C percentages and estimated average glucose, or eAG. Some people call it a glucose to A1C calculator, an A1C converter, or an A1C conversion calculator — they all perform the same core conversion in one direction or both. Our A1C calculator goes a step further by also estimating your A1C from a running list of your own meter readings, which is the closest you can get to a home A1C estimate between lab tests.
You might want to use an A1C to eAG calculator if your doctor mentioned your A1C in a percentage but you think in blood sugar numbers, if your continuous glucose monitor (CGM) reports mean glucose and you want to know your approximate A1C, or if you simply want to track your estimated average glucose between quarterly lab visits. Because the A1C to average glucose conversion uses a single published formula, any accurate A1C conversion calculator will give you the same numbers — what matters is a clean interface, both unit systems, and a chart for quick reference.
There is also a very practical reason to convert blood sugar to A1C at home: it gives you feedback in weeks rather than months. Instead of waiting three months for your next lab draw, you can enter your recent glucose readings and see roughly where your A1C is trending. That early signal can motivate lifestyle changes — or reassure you that what you are doing is working — long before your next doctor's appointment.
Below we explain exactly how the A1C formula works, show worked examples for the A1C to glucose conversion and the glucose to A1C conversion, include a full A1C to eAG table and a reverse mg/dL to A1C table, and answer the most common questions about A1C, eAG, and GMI.
How to Calculate A1C: The A1C Formula Explained
The question "how is A1C calculated?" has two answers depending on what you mean. In the lab, A1C is measured directly: a technician separates glycated hemoglobin from unmodified hemoglobin and reports it as a percentage. But when you want to estimate A1C from average glucose — or convert A1C back to glucose — you use the ADAG formula, named after the A1c-Derived Average Glucose study. This is the formula behind the A1C calculator on this page, and it is the standard used by the American Diabetes Association.
The A1C to eAG formula (A1C to glucose conversion)
To convert A1C to blood sugar, take your A1C percentage, multiply it by 28.7, then subtract 46.7. The result is your estimated average glucose in mg/dL. To get mmol/L, divide that number by 18.0182. This A1C to blood sugar conversion lets you translate any A1C result into the same units you see on your glucose meter, which is why so many people look up an A1C to glucose chart before an appointment.
The glucose to A1C formula (reverse conversion)
To convert blood sugar to A1C, add 46.7 to your average glucose and divide by 28.7. If your glucose is in mmol/L, multiply it by 18.0182 first. This is the calculation behind "mg/dL to A1C" lookups — for example, an average of 140 mg/dL converts to an A1C of about 6.5%. The two formulas are exact inverses, so you can always check your work by converting back the other way.
Worked A1C calculation examples
Your A1C is 7.0%. eAG = 28.7 × 7.0 − 46.7 = 154 mg/dL. In mmol/L: 154 ÷ 18.0182 = 8.6 mmol/L. So a 7.0% A1C means an estimated average glucose of about 154 mg/dL — a common treatment target.
Your average glucose is 180 mg/dL. A1C = (180 + 46.7) ÷ 28.7 = 7.9%. So an average blood sugar of 180 mg/dL corresponds to an A1C of roughly 7.9%, which is above the 7.0% goal for most adults.
Your average glucose is 10.0 mmol/L. Convert to mg/dL: 10.0 × 18.0182 = 180 mg/dL. Then A1C = (180 + 46.7) ÷ 28.7 = 7.9%. The calculator handles this unit conversion automatically, so you never need to do the extra step.
This is the most searched A1C to eAG conversion because 6.5% is the diabetes diagnostic threshold. eAG = 28.7 × 6.5 − 46.7 = 140 mg/dL, or 7.8 mmol/L. If your A1C is 6.5%, your average blood sugar is about 140 mg/dL.
A1C to eAG Conversion Chart
The table below shows the most common A1C to glucose conversion values using the ADAG formula. For the complete reference, open the full A1C to eAG conversion chart, which covers every A1C from 4.0% to 14.0% in both mg/dL and mmol/L. Bookmark it as your personal A1C to blood sugar conversion chart and refer to it whenever you get a new A1C result.
| A1C (%) | eAG (mg/dL) | eAG (mmol/L) |
|---|---|---|
| 5.0% | 97 mg/dL | 5.4 mmol/L |
| 5.7% | 117 mg/dL | 6.5 mmol/L |
| 6.0% | 126 mg/dL | 7.0 mmol/L |
| 6.5% | 140 mg/dL | 7.8 mmol/L |
| 7.0% | 154 mg/dL | 8.6 mmol/L |
| 7.5% | 169 mg/dL | 9.4 mmol/L |
| 8.0% | 183 mg/dL | 10.2 mmol/L |
| 9.0% | 212 mg/dL | 11.8 mmol/L |
| 10.0% | 240 mg/dL | 13.3 mmol/L |
Reading the chart is simple: find your A1C percentage in the first column and look across for your estimated average glucose. Notice how the values climb steadily — because the formula is linear, every 28.7 mg/dL of average glucose moves the A1C by exactly one percentage point. That linear relationship is what makes the A1C to eAG conversion so predictable and easy to reason about.
Glucose to A1C Conversion: mg/dL to A1C Table
If you know your average blood sugar and want the reverse conversion, use this mg/dL to A1C reference table. These values answer the popular "125 glucose to A1C," "140 mg/dL to A1C," and similar long-tail questions — the exact A1C to eAG formula applied backwards. The interactive A1C calculator above converts any value, including ones not listed here, using the same glucose to A1C calculation.
| Glucose (mg/dL) | A1C (%) | Glucose (mmol/L) |
|---|---|---|
| 80 | 4.4% | 4.4 |
| 100 | 5.1% | 5.6 |
| 110 | 5.5% | 6.1 |
| 120 | 5.8% | 6.7 |
| 125 | 6.0% | 6.9 |
| 130 | 6.2% | 7.2 |
| 140 | 6.5% | 7.8 |
| 150 | 6.9% | 8.3 |
| 160 | 7.2% | 8.9 |
| 170 | 7.6% | 9.4 |
| 180 | 7.9% | 10.0 |
| 200 | 8.6% | 11.1 |
| 220 | 9.3% | 12.2 |
| 240 | 10.0% | 13.3 |
| 260 | 10.7% | 14.4 |
| 280 | 11.4% | 15.5 |
| 300 | 12.1% | 16.6 |
Notice how the conversion behaves: because the ADAG formula is linear, each 28.7 mg/dL of average glucose changes the A1C by one full percentage point. That is why an average of 126 mg/dL sits at 6.0%, 154 mg/dL at 7.0%, and 183 mg/dL at 8.0%. Knowing this pattern makes the A1C to blood sugar conversion easy to sanity-check even without a calculator — if you remember the 140 mg/dL → 6.5% anchor, you can estimate any nearby value.
Average Blood Sugar to A1C: From Your Meter Readings
The most practical use of a glucose to A1C calculator is converting your own average blood sugar to an estimated A1C between lab visits. Enter the readings from your glucose meter — fasting, before meals, and after meals — and the average glucose to A1C tool on this page calculates the mean and converts it with the ADAG formula. The more readings you log and the more days they cover, the closer the estimate will be to your next lab A1C.
For best results, sample readings across different times of day. Fasting values alone tend to run lower than your true 24-hour average, so include after-meal readings too. Over a two-to-three-week period, a mix of twenty to thirty readings gives a much more representative average than a handful of fasting checks. If you use a CGM, the mean glucose it already reports over 14 days is an excellent input for this same average glucose to A1C estimate.
Keep in mind that a true A1C test is weighted by the age of your red blood cells, so a single week of readings can only approximate the 3-month average. The A1C to average glucose numbers this calculator produces are estimates, not a diagnosis — treat them as a useful tracking signal, and rely on the lab test for clinical decisions. For the reverse direction, an estimated average glucose value converts back to A1C with the same formula, which is exactly what the "Glucose → A1C" tab does.
Why eAG Matters for Managing Diabetes
Estimated average glucose exists for a simple reason: most people do not think in percentages. If your doctor tells you your A1C is 7.0%, it is not immediately obvious how that relates to the 140 mg/dL number on your meter. The A1C to eAG conversion bridges that gap, giving you a single number you can compare against your daily readings. Many clinics now print eAG right next to A1C on lab reports for exactly this reason.
Tracking eAG between appointments also gives you a more intuitive way to see progress. Instead of waiting three months to see whether your A1C dropped, you can watch your running average glucose month by month. Because eAG and A1C move together — a 10 mg/dL change in average glucose is roughly a 0.35% change in A1C — improving your average glucose by 20 mg/dL translates to roughly a 0.7% drop in A1C. That is a meaningful change that shows up long before your next lab test.
GMI to A1C: The Glucose Management Indicator
If you wear a continuous glucose monitor (CGM), your device likely reports a metric called the Glucose Management Indicator, or GMI. GMI is a newer, A1C-like percentage derived from your CGM's mean glucose over 10–14 days. GMI and A1C both estimate average glucose, so they are closely related — but they are not identical, and GMI can differ from a lab A1C by about 0.5% for reasons like red blood cell lifespan or calibration.
To convert a GMI percentage back to a glucose number, or to compare GMI to A1C, use our dedicated GMI to A1C calculator with its own conversion chart. The GMI to A1C calculator and the GMI to A1C chart on that page help CGM users understand how their sensor's mean glucose maps to both GMI and estimated A1C, so the numbers on your phone and the number from your lab tell a consistent story.
Normal A1C Levels and Blood Sugar Ranges
Understanding where your number falls is just as important as converting it. The clinical ranges below are the standard A1C levels used for diagnosis and monitoring. The result panel of our A1C calculator highlights your range automatically — green for normal, amber for prediabetes, and red for the diabetes range — so you instantly see the category your estimated average glucose lands in.
| Category | A1C | eAG (mg/dL) | What it means |
|---|---|---|---|
| Normal | Below 5.7% | Below 117 | No diabetes; keep up healthy habits |
| Prediabetes | 5.7 – 6.4% | 117 – 140 | At risk; lifestyle changes can help reverse it |
| Diabetes | 6.5% or higher | 140 or higher | Diabetes range; follow your care plan |
These A1C levels are used by the American Diabetes Association and most clinicians. If your estimated average glucose or A1C to eAG result sits at a boundary, remember that a single conversion is an estimate — diagnosis requires a formal A1C blood test, usually repeated to confirm. For normal blood sugar targets, most people without diabetes fast between 70 and 99 mg/dL, which corresponds to an A1C well below 5.7%.
It is also worth understanding the two standard ways blood sugar is measured. Milligrams per deciliter (mg/dL) is the convention in the United States, while millimoles per liter (mmol/L) is used in most other countries. The relationship between them is fixed: 1 mmol/L equals 18.0182 mg/dL. Whether you convert A1C to eAG or glucose to A1C, always keep the unit system in mind — mixing them up is the most common mistake people make with conversion charts.
A1C Levels by Age and Special Populations
The diagnostic ranges in the table above apply to most healthy adults regardless of age — a normal A1C is below 5.7% for a 25-year-old and a 70-year-old alike. Where age becomes relevant is the treatment target for people who already have diabetes. Many adults aim for an A1C of 7.0% or lower, but younger people with new-onset diabetes and long life expectancy are often given stricter targets like 6.5%, while older adults or those with other health conditions may have individualized goals of 7.5% or higher to avoid the risks of overtreatment, such as hypoglycemia.
Special situations can also change how A1C should be interpreted. Pregnancy lowers the normal A1C range because red blood cell turnover increases, so most clinicians use separate pregnancy-specific targets. People with anemia, recent blood loss, iron deficiency, or kidney disease may have A1C results that do not match their true average glucose, and clinicians sometimes turn to alternative markers or CGM data instead. If your A1C to eAG result seems out of line with how you feel or with your meter readings, bring it up with your doctor — there may be more going on than the formula can capture.
Limitations of the A1C to eAG Conversion
The ADAG formula is remarkably consistent for most people, but it is not perfect. Because it is a population average, individual A1C to glucose relationships can vary. Red blood cell lifespan is the biggest factor: if your cells live longer or shorter than average, your A1C can run higher or lower than your true average glucose would predict. This is why some conditions — anemia, recent blood loss, kidney disease, or certain hemoglobin variants — can make A1C less reliable.
That does not mean the A1C to eAG conversion is not useful. For the vast majority of people, it is accurate enough for tracking and communication, and it is the exact approach used by the American Diabetes Association's official eAG tables. Just treat the numbers as estimates, and if your A1C and your meter readings disagree by more than expected, mention it to your clinician — it can point to one of the factors above or a calibration problem.
In practice, the conversion is also directionally safe. Even when an individual result is off by half a percent, the A1C to eAG and glucose to A1C formulas still rank people correctly: someone at 8.0% will reliably estimate a higher average glucose than someone at 6.0%. So whether you are using the calculator to convert A1C to eAG, check a specific mg/dL to A1C value, or track your average glucose to A1C trend over time, the relative signal is dependable even when the absolute number needs a grain of salt.
Tips for an Accurate A1C Test and Better Results
A few habits keep your A1C lab result meaningful. First, consistency matters: schedule your test at a similar time of day and let your clinic know about any recent illnesses, blood transfusions, or iron supplements, all of which can skew results. Second, be honest with your meter — skip-logging high readings only makes your average glucose to A1C estimate look better than reality, which hides problems.
If you are working to lower A1C, focus on sustainable changes: replace sugary drinks with water, add a short walk after meals, build muscle with resistance training, and prioritize sleep, since poor sleep is linked to higher morning glucose. Most people see a roughly 1% A1C improvement within three months of consistent changes. Use the A1C calculator to convert every lab result and every home average into the same comparable number, and you will have a clean trend line to share with your care team.
A1C to eAG — Frequently Asked Questions
Below are the most common questions about the A1C to eAG conversion, the glucose to A1C formula, and how these numbers relate to your daily blood sugar management. If your exact question is about a specific value, plug it into the A1C calculator above — it converts any A1C or glucose number instantly.
What does A1C stand for?
A1C stands for hemoglobin A1C (HbA1c) — the percentage of your hemoglobin that has glucose attached to it. Because red blood cells live about three months, A1C reflects your average blood sugar over the past 2–3 months and is the standard test for diagnosing and monitoring diabetes.
How is A1C calculated from average glucose?
Using the ADAG formula: A1C = (eAG + 46.7) ÷ 28.7. For example, an average glucose of 140 mg/dL converts to an A1C of about 6.5%. This glucose to A1C calculation is the reverse of the A1C to eAG formula and is what the "Glucose → A1C" tab performs instantly.
How to convert A1C to average blood sugar?
Multiply your A1C by 28.7 and subtract 46.7. An A1C of 7.0 converts to an estimated average glucose of about 154 mg/dL (8.6 mmol/L). This A1C to blood sugar conversion is the same formula used by the American Diabetes Association.
What is a normal A1C level?
Normal is below 5.7%. An A1C of 5.7–6.4% indicates prediabetes, and 6.5% or higher indicates diabetes. Below 5.7% corresponds to an estimated average glucose under 117 mg/dL, which matches a fasting blood sugar range of 70–99 mg/dL.
What does a 6.5 A1C mean in blood sugar?
An A1C of 6.5% corresponds to an estimated average glucose of about 140 mg/dL (7.8 mmol/L). An A1C of 6.5% or higher, confirmed on a second test, is used to diagnose diabetes.
What is 140 mg/dL glucose to A1C?
An average blood glucose of 140 mg/dL converts to an A1C of about 6.5% using the ADAG formula: (140 + 46.7) ÷ 28.7 = 6.5%. This is one of the most searched glucose to A1C conversions because 140 mg/dL marks the diabetes diagnostic threshold.
What is 125 mg/dL glucose to A1C?
An average glucose of 125 mg/dL converts to an A1C of about 6.0%. Values around 125–126 mg/dL sit right at the diagnostic threshold for diabetes, so knowing the exact A1C equivalent is especially useful.
What is 100 mg/dL to A1C?
An average blood sugar of 100 mg/dL converts to an A1C of about 5.1%, which falls comfortably in the normal range below 5.7%. Many people search "100 mg/dl to a1c" to confirm that a fasting reading of 100 mg/dL is on the upper end of normal.
What is 150 mg/dL glucose to A1C?
An average glucose of 150 mg/dL converts to an A1C of about 6.9%, which places you in the diabetes range. Use the glucose-to-A1C direction of the calculator to convert any value you encounter on your meter.
How to convert mg/dL to A1C?
Add 46.7 to your mg/dL value and divide by 28.7. For example, 180 mg/dL: (180 + 46.7) ÷ 28.7 = 7.9%. Our free A1C calculator does this instantly, and the mg/dL to A1C table above lists the most common values.
What is the A1C to eAG conversion formula?
The ADAG formula is eAG (mg/dL) = 28.7 × A1C − 46.7. To convert to mmol/L, divide by 18.0182. For example, 6.5% A1C → 28.7 × 6.5 − 46.7 = 140 mg/dL (7.8 mmol/L).
What is the difference between A1C and average blood sugar?
A1C is a percentage of glycated hemoglobin that reflects your 3-month glucose average, while blood sugar (glucose) is the real-time concentration in your blood. A1C converts to estimated average glucose (eAG) so the two can be compared directly.
What is a normal blood sugar level?
For most people without diabetes, fasting blood sugar is 70–99 mg/dL (3.9–5.5 mmol/L). A normal A1C below 5.7% corresponds to an estimated average glucose under 117 mg/dL. Post-meal blood sugar typically rises but returns to baseline within two hours.
What is the GMI to A1C conversion?
GMI (Glucose Management Indicator) converts your CGM mean glucose into an A1C-like percentage using the formula GMI (%) = 3.31 + 0.02392 × mean glucose in mg/dL. Because GMI and A1C use different formulas, compare them with the dedicated GMI to A1C calculator rather than assuming they are equal.
What does 7.0 A1C mean in blood sugar?
An A1C of 7.0% converts to an estimated average glucose of about 154 mg/dL (8.6 mmol/L). It is the common treatment target for many people with diabetes and is a common benchmark on A1C to eAG charts.
What does 8.0 A1C mean in blood sugar?
An A1C of 8.0% converts to an estimated average glucose of about 183 mg/dL (10.2 mmol/L). At this level, your care team may adjust medication, diet, or exercise plans to bring glucose down.
What does 9.0 A1C mean in blood sugar?
An A1C of 9.0% converts to an estimated average glucose of about 212 mg/dL (11.8 mmol/L). Consistently high A1C levels above this point increase the risk of diabetes complications and warrant a review of your treatment plan.
How accurate is the A1C to eAG conversion?
The ADAG formula is the standard validated conversion used by the ADA. For most people it is within roughly 1% of true average glucose, though individual variation exists due to red blood cell lifespan, hemoglobin variants, and other factors. Treat results as estimates, not laboratory measurements.
How often should A1C be checked?
People with diabetes typically have A1C checked every 3 months. Those with stable, well-controlled glucose may be checked every 6 months, per clinical guidelines. Between lab visits, an average glucose to A1C estimate from your meter readings can help you track progress.
How to lower your A1C?
Lowering A1C involves reducing refined carbohydrates and added sugar, increasing physical activity, managing stress, improving sleep, staying hydrated, and following your clinician's medication plan. A1C typically improves by about 1% over three months of consistent change. Ask your doctor before making changes.
What is a good A1C for a diabetic?
Many adults with diabetes aim for an A1C of 7.0% or lower, which equals an estimated average glucose of about 154 mg/dL. Targets are individualized based on age, health, and history — some people safely target higher, others lower. Your clinician sets the right number for you.
What is 6.0 A1C in blood sugar?
An A1C of 6.0% converts to an estimated average glucose of about 126 mg/dL (7.0 mmol/L). It sits within the prediabetes range of 5.7–6.4%.
What is 5.7 A1C in blood sugar?
An A1C of 5.7% converts to an estimated average glucose of about 117 mg/dL (6.5 mmol/L). This is the upper edge of the normal range and the start of prediabetes, so it is an important number to know on any A1C to eAG chart.
How to calculate A1C from a single blood sugar reading?
A single reading is not a reliable basis for an A1C estimate. The average glucose to A1C calculator works best when you enter many readings over several weeks, ideally including fasting and post-meal values. Your doctor's A1C blood test remains the gold standard.
What is eAG in the A1C test?
eAG stands for estimated average glucose. It is the average blood sugar your A1C result corresponds to, calculated with the ADAG formula so patients can relate the A1C percentage to everyday glucose readings. Many lab reports now display eAG next to A1C.
Does A1C to eAG conversion work for mmol/L?
Yes. Compute eAG in mg/dL first using eAG = 28.7 × A1C − 46.7, then divide by 18.0182 to get mmol/L. Our calculator outputs both units automatically, so you never need to convert manually.
Can I convert eAG back to A1C?
Yes — use the reverse formula A1C = (eAG + 46.7) ÷ 28.7. Switch the calculator to the "Glucose → A1C" tab to do this instantly, or use the mg/dL to A1C table for common values.
What is an A1C conversion chart?
An A1C conversion chart (also called an A1C to eAG chart, A1C to glucose chart, or glucose to A1C chart) lists A1C percentages alongside their estimated average glucose in mg/dL and mmol/L. View the full chart for every A1C from 4.0% to 14.0%.
Sources & Methodology
The conversions on this page use the A1c-Derived Average Glucose (ADAG) study formula — eAG (mg/dL) = 28.7 × A1C − 46.7 — the standard equation adopted by the American Diabetes Association for translating A1C into estimated average glucose. Diagnostic ranges (normal below 5.7%, prediabetes 5.7–6.4%, diabetes 6.5% or higher) follow current ADA criteria, and the GMI formula (GMI = 3.31 + 0.02392 × mean glucose) comes from the published CGM literature.
- Nathan et al., "Translating the A1C Assay Into Estimated Average Glucose Values" — New England Journal of Medicine (ADAG study)
- NIDDK — The A1C Test & Diabetes
- American Diabetes Association — Understanding A1C
Content last reviewed: August 3, 2026. All tools provide educational estimates only and are not medical advice, diagnosis, or treatment — always confirm results with a qualified healthcare professional.
Related Tools and Charts
Explore the rest of GlycoLab to get the full picture: learn the basics in our what is A1C guide, reference every value in the complete A1C to eAG conversion chart, or convert sensor data with the GMI to A1C calculator. All of our A1C tools use the same ADAG formula, so the numbers always agree.
Remember that every tool on this site is free to use and provides educational estimates only — they are not a substitute for medical advice, diagnosis, or treatment. Always discuss your A1C, eAG, and blood sugar results with a qualified healthcare professional, and follow the care plan they develop for you.