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A1C Calculator

Convert between HbA1c and average blood glucose levels

Normal: <4.0% | Prediabetes: 5.7-6.4% | Diabetes: ≥6.5%
Normal fasting: 70-100 mg/dL

A1C to Average Glucose Chart

A1C % eAG (mg/dL) eAG (mmol/L) Status
4% 68 mg/dL 3.8 mmol/L Normal
5% 97 mg/dL 5.4 mmol/L Normal
5.7% 117 mg/dL 6.5 mmol/L Prediabetes
6% 126 mg/dL 7.0 mmol/L Prediabetes
6.5% 140 mg/dL 7.8 mmol/L Diabetes
7% 154 mg/dL 8.6 mmol/L Diabetes (Goal for many)
8% 183 mg/dL 10.2 mmol/L Diabetes (Poor control)
9% 212 mg/dL 11.8 mmol/L Diabetes (Poor control)
10% 240 mg/dL 13.4 mmol/L Diabetes (Very poor control)
Export Results
What is A1C?

HbA1c (Hemoglobin A1c) measures your average blood sugar over the past 2-3 months.

It shows the percentage of hemoglobin proteins in your blood that are coated with sugar (glycated).

A1C Targets
  • Normal: Below 5.7%
  • Prediabetes: 5.7% - 6.4%
  • Diabetes: 6.5% or higher
  • Treatment Goal: Below 7% (for most diabetics)
  • Tight Control: Below 6.5% (if achievable without hypoglycemia)
How Often to Test
  • Well-controlled diabetes: Every 6 months
  • Poorly controlled or changing treatment: Every 3 months
  • No diabetes: Screening every 3 years (age 45+)
  • Prediabetes: Annual testing
Learn More

Diabetes Management:

Understanding A1C Testing

How A1C Works

When glucose enters your bloodstream, it binds to hemoglobin (the protein in red blood cells that carries oxygen). This process is called glycation. The more glucose in your blood, the more glycated hemoglobin you have.

Since red blood cells live for about 2-3 months, the A1C test reflects your average blood sugar during that time period. It's not affected by short-term changes like what you ate before the test.

The A1C Formula

The relationship between A1C and average glucose is:

eAG (mg/dL) = 28.7 × A1C - 46.7

For example, an A1C of 7% corresponds to an estimated average glucose (eAG) of approximately 154 mg/dL or 8.6 mmol/L.

A1C vs. Daily Blood Sugar Testing

Aspect A1C Test Daily Glucose Testing
Time Frame 2-3 months average Moment-in-time snapshot
Frequency Every 3-6 months Multiple times daily
Fasting Required No Depends on type of test
What It Shows Overall diabetes control Impact of food, medication, activity
Limitations Doesn't show daily fluctuations Doesn't show long-term trends
Best For Assessing treatment effectiveness Day-to-day management decisions

A1C Targets by Population

General Adult Target

< 7%

American Diabetes Association (ADA) recommendation for most adults with diabetes

Stricter Control

< 6.5%

For younger people with recent diagnosis, no cardiovascular disease, if achievable without hypoglycemia

Relaxed Target

< 8%

For older adults, those with complications, limited life expectancy, or history of severe hypoglycemia

Factors That Can Affect A1C Results

Conditions That May Increase A1C

  • Iron deficiency anemia: Can falsely elevate A1C
  • Vitamin B12 deficiency: May increase A1C
  • Kidney disease: Can affect red blood cell lifespan
  • Alcohol consumption: Heavy drinking may increase A1C

Conditions That May Decrease A1C

  • Hemolytic anemia: Shortened red blood cell lifespan
  • Recent blood loss or transfusion: Younger red blood cells
  • Chronic liver disease: May lower A1C
  • Pregnancy: Can affect red blood cell turnover

How to Lower Your A1C

Lifestyle Changes

  • Healthy diet: Focus on whole grains, vegetables, lean protein, healthy fats. Limit refined carbs and sugars.
  • Regular exercise: 150 minutes/week of moderate activity. Exercise helps cells use insulin better.
  • Weight loss: Losing 5-10% of body weight can significantly improve A1C.
  • Portion control: Managing carbohydrate intake at each meal.
  • Stress management: Chronic stress raises blood sugar. Try meditation, yoga, or deep breathing.
  • Sleep quality: Aim for 7-9 hours. Poor sleep affects insulin sensitivity.

Medical Management

  • Medication adherence: Take diabetes medications as prescribed.
  • Regular monitoring: Check blood sugar as recommended by your doctor.
  • Insulin optimization: Work with your doctor to adjust doses.
  • New medications: GLP-1 agonists, SGLT2 inhibitors may help.
  • Continuous glucose monitoring (CGM): Provides detailed glucose patterns.
  • Regular checkups: Work closely with your healthcare team.

Realistic expectations: A 1% reduction in A1C typically takes 2-3 months of consistent effort.

A1C and Diabetes Complications

Why A1C Matters

High A1C levels over time increase the risk of diabetes complications:

  • Eye damage (retinopathy): Leading cause of blindness
  • Kidney disease (nephropathy): Can lead to kidney failure
  • Nerve damage (neuropathy): Pain, numbness, digestive issues
  • Heart disease: 2x higher risk of heart attack, stroke
  • Foot problems: Ulcers, infections, possible amputation
  • Skin conditions: Infections, slow wound healing
  • Hearing impairment: Nerve damage can affect hearing
  • Cognitive decline: Increased risk of dementia

Good news: The DCCT study showed that reducing A1C by 1% reduces complication risk by 25-40%.

Real-World Statistics

37M

Americans have diabetes

96M

Have prediabetes

50%

Diabetics at A1C goal

58%

Prediabetes can be prevented

Frequently Asked Questions

For most adults with diabetes, the American Diabetes Association recommends an A1C below 7%. However, targets should be individualized. Younger people with recent diagnosis and no complications may aim for <6.5%, while older adults or those with severe hypoglycemia history might target <8%. Your doctor will help determine the right goal based on your age, overall health, complications, and how long you've had diabetes.

Yes. While an A1C below 5.7% is considered normal for people without diabetes, for those taking diabetes medications (especially insulin), very low A1C levels can indicate frequent hypoglycemia (low blood sugar), which is dangerous. Severe hypoglycemia can cause confusion, seizures, loss of consciousness, or even death. If you have diabetes and your A1C is very low but you're experiencing frequent lows, your doctor may adjust your treatment plan. The goal is stable blood sugar, not just a low number.

Since A1C reflects your average blood sugar over 2-3 months, it takes at least that long to see significant changes. Most people can expect to lower their A1C by 0.5-1% in 2-3 months with consistent lifestyle changes or medication adjustments. A reduction of 1-2% is realistic over 3-6 months. Rapid drops are possible with major interventions (starting insulin, dramatic diet changes), but sustainable change typically requires patience. Focus on daily blood sugar control—the A1C will follow.

No, A1C testing does not require fasting. You can have the test done at any time of day regardless of when you last ate. This is one of the major advantages of A1C testing over fasting blood glucose tests. However, your doctor may order both A1C and fasting glucose tests on the same visit—in that case, you would need to fast for the glucose test, but not specifically for the A1C. The A1C measures long-term average, so a recent meal won't affect the result.

In rare cases, yes. A1C can be falsely normal in conditions that shorten red blood cell lifespan (like hemolytic anemia) or after recent blood loss/transfusion. Some people also have highly variable blood sugars—normal most of the time but with dangerous spikes after meals—resulting in a misleadingly normal A1C. This is why doctors sometimes use additional tests like fasting glucose, oral glucose tolerance test (OGTT), or continuous glucose monitoring (CGM). If you have diabetes symptoms but normal A1C, discuss additional testing with your doctor.

A1C is reported as a percentage (e.g., 7%), while eAG (estimated average glucose) converts that percentage into the same units you see on your home glucose meter—mg/dL or mmol/L. They represent the same thing, just in different units. eAG was introduced to help people better understand their A1C in terms they're already familiar with from daily testing. For example, an A1C of 7% equals an eAG of approximately 154 mg/dL. Many lab reports now include both A1C and eAG to make results more meaningful.
Medical Disclaimer

This A1C calculator is for educational purposes only and should not replace professional medical advice. A1C targets should be individualized based on your age, health status, diabetes duration, and other factors. Always consult with your healthcare provider to determine the appropriate A1C goal for you and to interpret your test results. If you have diabetes or prediabetes, work with your medical team to develop a comprehensive treatment plan.