π©Έ Estimated Average Glucose Calculator
A1C in, daily-average glucose out.
For informational purposes only, not medical advice. Consult a healthcare professional.
An A1C of 7.0% means an estimated average glucose of about 154 mg/dL (8.6 mmol/L). The ADAG formula behind it: eAG = 28.7 Γ A1C β 46.7. Every 1-point rise in A1C adds roughly 29 mg/dL to the average. Convert either direction above.
How to Use This Calculator
eAG translates the A1C percentage into the same units as your meter or CGM, so the lab number and the daily numbers speak the same language.
Enter your A1C percent from the lab report. The calculator converts it to estimated average glucose in mg/dL and mmol/L.
Or flip the direction: enter your meter or CGM average glucose to see the A1C it corresponds to. Useful when the lab result surprises you.
Compare the eAG against your actual meter average. A big gap between them is information, not an error: it points at red-cell or timing factors worth discussing.
The ADAG Formula
The formula comes from the ADAG study (Nathan et al., 2008), which paired continuous glucose monitoring with A1C in over 500 people with and without diabetes. The relationship is strikingly linear across the range, with a correlation near 0.92. The American Diabetes Association adopted eAG reporting so patients could map "my A1C is 8" to "my average sugar runs about 183," which is far more actionable. Note the intercept: an A1C of 5% gives eAG β 97 mg/dL, matching non-diabetic averages nicely.
Worked Example and Full Table
A1C 7.0%: 28.7 Γ 7 β 46.7 = 200.9 β 46.7 = 154.2 mg/dL, or 8.6 mmol/L. Reverse: an average glucose of 154 mg/dL gives (154 + 46.7)/28.7 = 6.99%, confirming the round trip.
| A1C | eAG mg/dL | eAG mmol/L |
|---|---|---|
| 5.0% | 97 | 5.4 |
| 5.7% | 117 | 6.5 |
| 6.0% | 126 | 7.0 |
| 6.5% | 140 | 7.8 |
| 7.0% | 154 | 8.6 |
| 8.0% | 183 | 10.2 |
| 9.0% | 212 | 11.8 |
| 10.0% | 240 | 13.3 |
The 5.7% and 6.5% rows are the prediabetes and diabetes diagnostic thresholds translated into averages: 117 and 140 mg/dL. I checked each row against the formula directly. The ADA's general A1C target of under 7% for most adults with diabetes is, in glucose terms, an average under 154 mg/dL.
When eAG and Your Meter Disagree
A gap between eAG and your meter average is common and meaningful. A1C reflects glucose attached to hemoglobin over the red cell's ~120-day life, weighted toward recent weeks. Anything that changes red-cell lifespan changes A1C independently of glucose: anemia, iron deficiency, and hemoglobin variants raise or lower it; blood loss, hemolysis, and erythropoietin treatment lower it by adding young red cells. Kidney disease, pregnancy, and recent transfusion all distort it. If your meter says 140 average and the lab says A1C 8.0% (eAG 183), believe the meter for day-to-day management and ask your clinician about alternative markers like fructosamine or CGM-derived time-in-range. The formula is right on average; individuals with red-cell quirks are the known exceptions. For the diagnostic side of the same number, our hemoglobin A1C interpreter covers what each A1C band means, and our diabetes risk calculator estimates risk before the lab work.
Using eAG With a CGM
CGM users get a measured average glucose, which makes eAG a cross-check rather than the main event. The modern metrics that matter alongside it: time in range (70-180 mg/dL), with targets of 70%+ for most adults, and the glucose management indicator (GMI), the CGM's own A1C estimate. When GMI and lab A1C disagree persistently, the red-cell factors above are usually why, and many clinicians then manage to time-in-range instead. eAG's real value is for people without CGM: it turns the quarterly lab number into a daily-average concept they can act on with food, activity, and medication timing.
Targets in Plain Numbers
Most nonpregnant adults with diabetes: A1C under 7%, average under 154 mg/dL. Tighter (under 6.5%) suits younger, healthier patients where hypoglycemia risk is low; looser (under 8%) suits older adults with limited life expectancy or hypoglycemia risk. Pregnancy targets are much tighter (A1C under 6-6.5% if achievable safely). These are starting points your clinician personalizes; the eAG translation just makes the target feel like a number you can steer with a meter rather than an abstract percent.
eAG and the Dawn Phenomenon
Many people find their meter average runs below their eAG, and the dawn phenomenon is a frequent reason: the liver releases glucose in the early morning hours, lifting fasting readings while daytime numbers look fine. Since A1C weights all hours equally but fingersticks sample waking hours, the lab sees what the meter misses. A CGM reveals the pattern directly: flat days with a 4-8 AM rise. If your eAG exceeds your meter average by more than ~15 mg/dL consistently, ask about overnight patterns before assuming the lab is wrong. Adjusting evening medication timing or addressing the dawn rise often closes the gap and lowers the next A1C.
For informational purposes only, not medical advice. Consult a healthcare professional.
Frequently Asked Questions
What is estimated average glucose?
The average blood glucose level corresponding to an A1C result, in mg/dL or mmol/L. It is calculated as eAG = 28.7 Γ A1C β 46.7 from the ADAG study, letting patients read their A1C in the same units as their glucose meter.
What is the eAG for an A1C of 7?
About 154 mg/dL (8.6 mmol/L). Each 1% of A1C equals roughly 29 mg/dL (1.6 mmol/L) of average glucose, so 6% is ~126, 8% is ~183, and 9% is ~212.
Is eAG the same as my meter average?
Usually close but not identical. eAG is estimated from A1C, which reflects ~3 months weighted toward recent weeks; your meter average covers only when you test. Consistent gaps suggest red-cell factors affecting A1C.
Why is my A1C high but my glucose readings normal?
Red-cell factors: iron deficiency, hemoglobin variants, and anything lengthening red-cell life raise A1C without raising glucose. Discuss fructosamine or CGM-based metrics with your clinician if the gap persists.
What is the ADAG study?
A1C-Derived Average Glucose: a 2008 study (Nathan et al.) that paired continuous glucose monitoring with A1C measurements in 507 people, establishing the linear formula relating A1C to average glucose with correlation ~0.92.
What eAG corresponds to the diabetes diagnosis threshold?
A1C 6.5% (the diabetes cutoff) equals eAG ~140 mg/dL (7.8 mmol/L). Prediabetes at 5.7% equals ~117 mg/dL. Normal under 5.7% is under ~117.
How do I convert mmol/L to mg/dL for glucose?
Multiply mmol/L by 18 (more precisely 18.015). So 8.6 mmol/L Γ 18 = 154.8 mg/dL. The US uses mg/dL; most of the rest of the world uses mmol/L.
Does eAG account for glucose swings?
No. Two people with eAG 154 can have very different variability: one steady near 154, another swinging 60 to 300. Time-in-range from a CGM captures what eAG misses, which is why both matter.
What A1C should I target?
The ADA suggests under 7% (eAG under 154 mg/dL) for most nonpregnant adults, personalized up or down. Tighter for young and healthy, looser where hypoglycemia risk is high. Your clinician sets your target.
Can eAG replace A1C testing?
No. eAG is derived from A1C, not a substitute measurement. It is a translation layer that makes the lab result interpretable in meter units. You still need the A1C blood test.