About this tool
The A1C to Glucose Converter is a free, in-browser tool that translates between the four common ways of expressing long-term blood glucose: HbA1c percent (NGSP), estimated average glucose (eAG) in mg/dL and in mmol/L, and the IFCC unit mmol/mol. Enter any one of them and the other three are calculated instantly, along with the standard ADA band (normal, prediabetes or diabetes range) for the corresponding A1C.
The conversions use the internationally standardized formulas: the ADAG study relationship eAG (mg/dL) = 28.7 × A1C − 46.7, mmol/L = mg/dL ÷ 18.016, and IFCC (mmol/mol) = (A1C − 2.15) × 10.929. Note that eAG is a statistical estimate — your meter or CGM average can legitimately differ from it. Everything is computed locally in your browser.
This tool is informational only — it is not medical advice.
Frequently asked questions
What formulas are used?
The ADAG study regression eAG = 28.7 × A1C − 46.7 (mg/dL), division by 18.016 for mmol/L, and the NGSP↔IFCC master equation IFCC = (A1C − 2.15) × 10.929 in mmol/mol — the same relationships the ADA and IFCC publish.
Why doesn't eAG match my meter average?
eAG is a population-level estimate: red-cell lifespan, glycation rate and when you test all vary between people, so a real 90-day meter or CGM average often differs somewhat from the eAG for the same A1C.
What are the ADA bands shown?
For a laboratory A1C, below 5.7% is considered normal, 5.7–6.4% prediabetes, and 6.5% or higher is in the diabetes range — diagnosis additionally requires confirmed lab testing, not a converted estimate.
Is this a diagnosis or medical advice?
No. This is a unit conversion for information only; it cannot diagnose or rule out diabetes, and treatment decisions should be based on lab results interpreted by your clinician.
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