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FitnessConvert between A1C and average blood sugar, both directions.
This tool is for general information only and is not medical advice. Talk to a healthcare professional about results that concern you.
What A1C Measures
A1C (also written HbA1c) measures the percentage of your red blood cells that have sugar attached to their hemoglobin. Because red blood cells live about three months, A1C reflects your average blood sugar over roughly the past 90 days, which makes it far more informative than a single finger prick that only shows this moment.
This converter uses the ADAG study formula adopted by the American Diabetes Association: estimated average glucose (eAG) in mg/dL = 28.7 x A1C – 46.7. It works in both directions, so you can turn a lab A1C into an everyday glucose number or estimate your A1C from your meter’s average.
A1C Ranges
| A1C | Range | Average glucose |
|---|---|---|
| Below 5.7% | Normal | below 117 mg/dL |
| 5.7% to 6.4% | Prediabetes | 117 to 137 mg/dL |
| 6.5% and above | Diabetes range | 140 mg/dL and up |
For people already managing diabetes, the common treatment target is an A1C below 7 percent, though your doctor may set a different goal based on age, medications, and history. Prediabetes deserves attention precisely because it responds so well: modest weight loss and regular activity cut progression to type 2 diabetes by more than half in major trials. Our calorie calculator and step counter can help you start.
Frequently Asked Questions
Why does my meter average not match my lab A1C?
Meters sample the moments you test, usually mornings and before meals, while A1C captures all 24 hours including post-meal spikes and nights. Anemia, kidney disease, and some hemoglobin variants can also shift A1C independent of sugar levels.
How fast can A1C come down?
Because it reflects three months of blood sugar, meaningful change shows in 8 to 12 weeks. A drop of 0.5 to 1.0 points over three months from diet, activity, and medication changes is a realistic, strong result.
Do I need to fast for an A1C test?
No. A1C is unaffected by your last meal, which is one reason clinicians like it. Fasting is needed for a fasting glucose test, not for A1C.
Is A1C the same as blood sugar?
Related but different. Blood sugar is a snapshot in mg/dL or mmol/L that moves hour to hour. A1C is a three month average expressed as a percentage. The converter above translates between the two.
Sources
- Translating the A1C Assay Into Estimated Average Glucose Values (Nathan et al., Diabetes Care 2008) · PubMed Central (PMC)
- Diabetes Diagnosis & Tests | ADA · American Diabetes Association
- The A1C Test & Diabetes – NIDDK · NIH / NIDDK
- Hemoglobin A1C (HbA1c) Test: MedlinePlus Medical Test · MedlinePlus
This converter is educational. Diagnosis and treatment decisions require lab testing and a doctor.