Why this tool exists
Most A1C converters online are buried inside diabetes portals, ask for an email address, or quietly claim formulas that do not match the standard. This site exists to give one number, the conversion between A1C and estimated average glucose, as plainly and accurately as possible, with the formula stated on the page and no signup in the way.
It is built for the people who actually look these up: someone just diagnosed who wants to understand a 6.5% result in everyday blood sugar terms, a CGM user comparing sensor data to a lab draw, and caregivers translating a doctor's notes. None of them need an account. They need a reliable conversion and a clear explanation.
Who runs this site
GlycoLab is a small independent health-tools project, not a hospital, lab, or pharmaceutical company, and it is not affiliated with the American Diabetes Association or any device maker. The calculators run entirely in your browser. Nothing you type is uploaded, stored, or sold.
The site is maintained by a small editorial team that reviews the underlying formulas and reference ranges when clinical standards change, typically annually or on any major guideline update. Corrections and questions are welcome through the contact page.
How the numbers are verified
Every conversion on this site uses the ADAG formula published by the international ADAG study and adopted by the American Diabetes Association: eAG (mg/dL) = 28.7 × A1C − 46.7, with mmol/L found by dividing by 18.0182. Reference ranges follow the standard classification: normal below 5.7%, prediabetes from 5.7% to 6.4%, and diabetes at 6.5% or higher.
The full method, including every formula and assumption, is documented on the methodology page. The editorial standards that govern corrections and sourcing are on the editorial policy page.
What this tool is not
An A1C estimate is not a diagnosis, and a converter does not replace a lab test or a clinician. Red blood cell lifespan, anemia, kidney disease, and pregnancy can all move the true relationship between glucose and A1C. Use this tool to understand your numbers and to talk to your care team, never to decide treatment on your own.
You can start with the A1C calculator, read what A1C measures, or browse the full conversion chart.