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A1C calculator — convert A1C and glucose both ways
Free online A1C calculator and converter: turn your A1C into estimated average glucose (eAG) in mg/dL or mmol/L, or convert glucose/eAG back to A1C. It uses the American Diabetes Association's ADAG formula and shows where your result falls across the normal, prediabetes, and diabetes ranges — no app install required.
eAG means estimated average glucose. Choose the conversion direction, then enter the value and units from your report.
Estimated average glucose
140mg/dL
≈ 7.8 mmol/L
Diabetes rangeA single A1C is one data point. Vero reads your lab history and Apple Health data together, so it can tell you how your A1C is trending and what's moving it.
Understand your A1C with VeroA1C to average glucose chart
A1C measures the percentage of your hemoglobin coated in sugar, reflecting your average blood glucose over the previous 2–3 months. The estimated average glucose (eAG) puts that number into the mg/dL units you see on a glucose meter. Here's how the standard diagnostic ranges line up:
| A1C | Estimated average glucose | Category |
|---|---|---|
| Below 5.7% | Below 117 mg/dL (6.5 mmol/L) | Normal |
| 5.7% – 6.4% | 117–137 mg/dL (6.5–7.6 mmol/L) | Prediabetes |
| 6.5% or higher | 140 mg/dL (7.8 mmol/L) and up | Diabetes |
Diabetes is diagnosed at an A1C of 6.5% or higher, typically confirmed on a second test. Reference ranges and personal targets vary — always use the interpretation on your own lab report and your clinician's guidance.
The formula
The conversion comes from the A1C-Derived Average Glucose (ADAG) study:
To convert mg/dL to mmol/L, divide by 18.0182. The calculator reverses the same equation when you enter an average glucose to estimate the matching A1C.
Glucose to A1C conversion
If you know an estimated average glucose — from a meter, CGM average, or eAG on a lab report — you can estimate the matching A1C. This is an eAG-to-A1C conversion, not a diagnosis from one reading.
Example: 140 mg/dL average glucose ≈ 6.5% A1C. If your average is in mmol/L, multiply by 18.0182 first, or switch the calculator to mmol/L. Conditions that change red-blood-cell lifespan can make this estimate less reliable — use the interpretation on your own lab report.
Frequently asked questions
How do you convert A1C to average blood sugar?
Use the ADA-endorsed ADAG formula: estimated average glucose (mg/dL) = 28.7 × A1C − 46.7. For example, an A1C of 6.5% works out to about 140 mg/dL (7.8 mmol/L). To get mmol/L, divide the mg/dL value by 18.0182. The calculator above does both directions for you.
How do I convert eAG to A1C?
Rearrange the same ADAG equation: A1C = (eAG + 46.7) ÷ 28.7, where eAG is in mg/dL. Example: an average glucose of 154 mg/dL converts to about 7.0% A1C. Enter your eAG in the calculator above (mg/dL or mmol/L) and it returns the matching A1C instantly — useful when you know your meter average but not your lab A1C.
How do I convert glucose to A1C?
Use your estimated average glucose, not a single fingerstick. In mg/dL the ADAG reverse formula is A1C = (glucose + 46.7) ÷ 28.7. In mmol/L, convert to mg/dL first (multiply by 18.0182) or enter mmol/L in the calculator. Example: a 154 mg/dL average is about 7.0% A1C. A one-time reading cannot replace a lab A1C.
Is there an A1C calculator app?
You can use this free A1C calculator directly in your browser, with no download. It converts A1C and estimated average glucose (eAG) in either direction, using mg/dL or mmol/L. The separate Vero iPhone app can organize uploaded A1C results alongside your medications and nutrition for educational follow-up questions. An estimate does not replace a measured lab A1C or a clinician’s interpretation.
Is AIC the same as A1C?
Yes — "AIC" is a common misspelling of A1C (also written HbA1c or hemoglobin A1c). It is the same blood test that estimates your average blood glucose over about 2–3 months. An AIC converter and an A1C calculator use the same conversion.
What is a normal A1C level?
For most adults without diabetes, an A1C below 5.7% is considered normal. 5.7–6.4% falls in the prediabetes range, and 6.5% or higher on two tests is used to diagnose diabetes. Targets are individualized — many people with diabetes aim for under 7%, but your doctor may set a different goal based on age and health.
What is estimated average glucose (eAG)?
eAG translates your A1C into the same mg/dL (or mmol/L) units you see on a home glucose meter, making the number easier to relate to daily readings. It reflects your average blood sugar over roughly the previous 2–3 months, not a single moment.
Why doesn't my A1C match my daily glucose readings?
A1C is a 2–3 month average, so it can differ from recent meter readings. It can also be skewed by conditions that change red blood cell lifespan — anemia, recent blood loss or transfusion, pregnancy, and certain hemoglobin variants — which make the eAG estimate less reliable. Discuss any mismatch with your doctor.
How much can A1C change in 3 months?
Because A1C reflects roughly 3 months of average glucose, meaningful change shows up over that window. With consistent diet, activity, and medication changes, drops of 0.5–1.0 percentage points over 3 months are common, and larger drops are possible from higher starting points. Rapid, very large drops should be supervised by a clinician.
Keep exploring
Sources
This page draws on the following authoritative references.
- Translating the A1C Assay Into Estimated Average Glucose Values — Diabetes Care
- The A1C Test & Diabetes — National Institute of Diabetes and Digestive and Kidney Diseases
Medically reviewed by Antonieta Rueda, MD and Kyle R. Toth, MD · Last reviewed July 22, 2026
This calculator provides general estimates for informational purposes only and is not a substitute for personalized advice from a doctor. The A1C-to-glucose conversion is an estimate and may be less accurate in anemia, pregnancy, recent blood loss, and certain hemoglobin variants. Diabetes should be diagnosed and managed by a clinician.