A1C Calculator

A single A1C percentage can be hard to picture in everyday terms, which is where converting it to an estimated average glucose (eAG) helps. This tool moves in both directions: enter an A1C and see the matching eAG in mg/dL or mmol/L, or work backward from a glucose figure to an A1C. Because the result reflects roughly the past two to three months of blood sugar rather than a single morning reading, it offers a steadier view of long-term control and can flag prediabetes earlier. With 2026 guidance leaning toward proactive management, having that number in familiar units makes conversations with your provider more productive.

The math behind the conversion comes from a standardized formula built on a large body of clinical research. To get average glucose in conventional units, the tool applies eAG (mg/dL) = 28.7 × A1C - 46.7; for international units it uses eAG (mmol/L) = 1.59 × A1C - 2.59. Both equations approximate the glucose that has bonded to your red blood cells over their lifespan, which is what an A1C test actually measures.

Treat the eAG as an approximation rather than a precise reading. Things like an unusually short or long red blood cell lifespan, anemia, and certain other conditions can pull the real average away from the formula's output. The number this calculator produces is educational and is not a stand-in for a clinician's interpretation or a diagnosis, so bring your actual lab results to your doctor for guidance and any treatment decisions. It also helps to watch how your readings move across several tests, since one isolated value tells you far less than a trend shaped by your habits over time.