How to read this chart
Each row represents one A1C percentage and its statistically corresponding average glucose, calculated with the ADAG-derived formula (eAG mg/dL = 28.7 × A1C − 46.7) and the NGSP–IFCC master equation (IFCC mmol/mol = (A1C − 2.15) × 10.929). Rows are shaded by ADA diagnostic category so you can see at a glance whether a value falls in the normal, prediabetes, or diabetes range. Use the filter buttons to narrow the table to just one category, or scroll to find your own lab result and read across.
Remember: eAG is a statistical estimate from a population study, not a substitute for the number your lab actually reports. Use this chart to build intuition about what your A1C means in everyday glucose terms — not to override a lab result.
The full chart
| A1C % | IFCC mmol/mol | eAG mg/dL | eAG mmol/L | Category |
|---|
Commonly searched A1C values, explained
A few specific percentages come up constantly in questions and lab reports. Here's what each one means in context:
- 5.7% (≈ 117 mg/dL / 6.5 mmol/L / 39 mmol/mol) — the ADA's prediabetes threshold. Crossing this line doesn't mean a diabetes diagnosis; it's a signal that lifestyle changes now measurably reduce future risk.
- 6.0% (≈ 126 mg/dL / 7.0 mmol/L / 42 mmol/mol) — solidly within the prediabetes range, often prompting a more structured conversation about diet, activity, and annual retesting.
- 6.5% (≈ 140 mg/dL / 7.7 mmol/L / 48 mmol/mol) — the shared ADA/WHO/NICE diabetes diagnostic threshold, generally requiring confirmation on a second occasion or with a second test.
- 7.0% (≈ 154 mg/dL / 8.6 mmol/L / 53 mmol/mol) — a commonly cited treatment target for many adults with diabetes, though individual targets vary.
- 8.0% (≈ 183 mg/dL / 10.2 mmol/L / 64 mmol/mol) — above most general targets, though it may be an appropriate, deliberately relaxed target for some older adults or those with a history of severe hypoglycemia.
- 10.0%+ (≈ 240 mg/dL / 13.3 mmol/L / 86 mmol/mol) — reflects sustained high average glucose and typically prompts a more active review of treatment with a care team.
These reference points are exactly what the full table above calculates for every tenth of a percent, so you can look up your own lab value the same way.
How diagnostic thresholds compare across guidelines
Nearly every major diabetes body — the American Diabetes Association (ADA), the World Health Organization (WHO), and the UK's National Institute for Health and Care Excellence (NICE) — anchors on the same underlying threshold, just expressed in different units. That consistency is a direct result of the international NGSP/IFCC standardization work described on our formula page.
| Category | ADA (NGSP %) | NICE/WHO (IFCC mmol/mol) |
|---|---|---|
| Normal | Below 5.7% | Below 39 mmol/mol |
| Prediabetes / non-diabetic hyperglycaemia | 5.7% – 6.4% | 39 – 47 mmol/mol |
| Diabetes | 6.5% and above | 48 mmol/mol and above |
A diagnosis in any system generally requires either two abnormal results on separate occasions, or one abnormal A1C/HbA1c confirmed by a second test method, such as fasting plasma glucose or an oral glucose tolerance test — a single borderline number is a prompt for retesting, not an automatic diagnosis.
Chart limits for special populations
Pregnancy and gestational diabetes
This chart, and A1C testing generally, is not used to diagnose gestational diabetes mellitus (GDM). Pregnancy shortens red blood cell turnover and increases plasma volume, both of which distort the A1C-to-glucose relationship this chart is built on. GDM screening instead relies on a glucose challenge test or oral glucose tolerance test with direct glucose measurements. Women with pre-existing diabetes who become pregnant typically work with their care team toward a tighter individualized A1C target, often in the 6.0–6.5% range, rather than reading results off a general population chart.
Children, teens, and type 1 diabetes
The eAG relationship in this chart was derived primarily from adult participants. Children and teens with type 1 diabetes can have a different average glucose-to-A1C relationship, and pediatric endocrinology guidelines set age-specific targets that balance long-term risk reduction against the greater danger of hypoglycemia in young children. Use this chart for general orientation with a pediatric patient, but rely on a pediatric endocrinologist's individualized targets rather than the adult categories shown above.
Older adults and relaxed targets
For older adults with a long diabetes history, multiple coexisting conditions, or a history of severe hypoglycemia, many guidelines — including the ADA's — explicitly endorse a relaxed target above 7.0%, sometimes as high as 8.0–8.5%, because the risks of tight control (falls, hypoglycemic events) can outweigh the marginal benefit of a lower number in a shorter remaining lifespan. The "lower is always better" reading of this chart doesn't apply uniformly across every age and health context.
Using this chart alongside your own glucose data
If you track glucose with a meter or continuous glucose monitor, you can use this chart in reverse: take your device's reported average over 2–3 months, find the closest eAG value in the mg/dL or mmol/L column, and read across to see the A1C that average would predict. This is exactly what the glucose-to-A1C calculator on our homepage automates. It's a useful sanity check between lab visits, but treat it as a planning estimate rather than a confirmed result — only a laboratory draw produces a certified A1C.
For the statistical reasoning behind every number in this table, including why an individual result can reasonably sit ±15–20 mg/dL off the line, see our full formula breakdown.