A1c Calculator & Blood Sugar Converter
Convert HbA1c to average glucose and blood sugar between mg/dL and mmol/L, with diagnostic ranges.
Enter an HbA1c result to see the result.
Converts an HbA1c result between percent and mmol/mol and into the average blood sugar it stands for, and converts a blood sugar reading between mg/dL and mmol/L. Each result is placed in the diagnostic bands of the guideline you choose: the American Diabetes Association (ADA), the World Health Organization (WHO), NICE in the UK, or the Indian Council of Medical Research (ICMR). Every calculation runs in your browser.
Understanding the result
HbA1c reflects average blood sugar over roughly the last 3 months, so it changes slowly; a single blood sugar reading is a moment. The bands are for adults who are not pregnant. With Pregnant ticked, or an age under 18 saved by another health tool on this device, the tool converts the result but shows no band.
- ADA 2026 — prediabetes from an HbA1c of 5.7% (39 mmol/mol) or a fasting sugar of 100 mg/dL (5.6 mmol/L); the diabetes range from 6.5% (48), 126 mg/dL (7.0), or 200 mg/dL (11.1) two hours into a glucose tolerance test.
- WHO — the same diabetes lines, but impaired fasting glucose starts higher, at 6.1 mmol/L (110 mg/dL). WHO accepts an HbA1c of 6.5% as diabetes and sets no band below it: a lower result does not rule diabetes out.
- NICE — "high risk" of type 2 diabetes for a fasting sugar of 5.5 to 6.9 mmol/L or an HbA1c of 42 to 47 mmol/mol (6.0–6.4%). Above that the tool gives WHO's diabetes range.
- ICMR 2018 — prints both fasting lines: 100 to 109 mg/dL is prediabetes under ADA's criteria and normal under WHO's, and 110 to 125 is prediabetes under both.
A result in the diabetes range is not a diagnosis on its own. ADA, WHO and ICMR all ask for a second abnormal test unless blood sugar is unequivocally high. A random reading is only placed in the diabetes range at 200 mg/dL (11.1 mmol/L) or more with classic symptoms; from 140 mg/dL, ICMR recommends a glucose tolerance test. A reading after a meal has no diagnostic band, and the tool gives ADA's after-meal goal for people with diabetes instead.
How it works
Glucose converts with its molar mass, 180.16 g/mol: 1 mmol/L is 18.0156 mg/dL. Readings show as whole mg/dL and mmol/L to one decimal, HbA1c as a percent to one decimal and mmol/mol as a whole number. HbA1c units are linked by the IFCC–NGSP master equation, and the estimated average glucose (eAG) is the line the ADAG study fitted from HbA1c to measured average glucose.
A result is classified once, in a unit the guideline prints. ADA and WHO print both glucose units, so a reading is read in the unit you typed; NICE prints only mmol/L and ICMR only mg/dL, so a reading in the other unit is converted and rounded first. A converted value that would display on the other side of a cut-off from the band it was given shows an extra decimal and "≈", so the number and the band never disagree. The printed pairs are rounded: 5.6 mmol/L is 100.9 mg/dL, not exactly 100.
mg/dL = mmol/L × 18.0156
HbA1c % = 0.09148 × mmol/mol + 2.152
eAG (mg/dL) = 28.7 × HbA1c % − 46.7
eAG (mmol/L) = 1.5944 × HbA1c % − 2.594
Examples
HbA1c 47 mmol/mol, ADA
Prediabetes. In percent it is ≈ 6.45%: rounded to one decimal it would read 6.5%, and the diabetes line is 6.5%, so the extra decimal keeps the figure with its band.
Fasting 109 mg/dL, WHO
Normal under WHO, shown as ≈ 6.05 mmol/L. Under ADA the same reading is prediabetes.
Fasting 5.55 mmol/L, ADA
Classified at one decimal as 5.6 mmol/L: prediabetes.
HbA1c to average glucose
| HbA1c % | mmol/mol | eAG mg/dL | eAG mmol/L |
|---|---|---|---|
| 5.0% | 31 | 97 | 5.4 |
| 6.0% | 42 | 126 | 7.0 |
| 7.0% | 53 | 154 | 8.6 |
| 8.0% | 64 | 183 | 10.2 |
| 9.0% | 75 | 212 | 11.8 |
| 10.0% | 86 | 240 | 13.4 |
| 11.0% | 97 | 269 | 14.9 |
| 12.0% | 108 | 298 | 16.5 |
Rules and sources
ADA's bands are Tables 2.1 and 2.2 of its 2026 Standards of Care, and the after-meal goal is Table 6.3. WHO's glucose bands are its 2006 report with IDF, and its HbA1c line the 2011 consultation. NICE's high-risk ranges are from PH38, and ICMR's from Table 3.1 of its 2018 type 2 diabetes guidelines. The eAG line is Nathan et al. (2008), fitted on adults aged 18 to 70 without anaemia or haemoglobin disorders, those with diabetes in stable control, and the unit equation is NGSP's.
In India, the RSSDI–ESI clinical practice recommendations (2020), from a professional society rather than a government body, advise against HbA1c as the only test for diagnosis or screening in most Indian settings.
Sources
- Chawla R et al. RSSDI–ESI Clinical Practice Recommendations for the Management of Type 2 Diabetes Mellitus 2020 (Indian J Endocrinol Metab 2020;24:1–122) — PubMed Central
- Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2026 (Diabetes Care 2026;49(Suppl 1):S27–S49), Tables 2.1 and 2.2 — American Diabetes Association
- Glycemic Goals, Hypoglycemia, and Hyperglycemic Crises: Standards of Care in Diabetes—2026 (Diabetes Care 2026;49(Suppl 1):S132–S149), Table 6.3 — American Diabetes Association
- Definition and diagnosis of diabetes mellitus and intermediate hyperglycaemia: report of a WHO/IDF consultation (2006) — WHO
- Use of glycated haemoglobin (HbA1c) in the diagnosis of diabetes mellitus: abbreviated report of a WHO consultation (2011) — WHO
- Type 2 diabetes: prevention in people at high risk (PH38), recommendations 1.1 — NICE
- ICMR Guidelines for Management of Type 2 Diabetes 2018, Table 3.1 — Indian Council of Medical Research
- Nathan DM et al. Translating the A1C assay into estimated average glucose values (Diabetes Care 2008;31:1473–1478) — PubMed Central
- IFCC standardization of HbA1c: the IFCC–NGSP master equation — NGSP
- D-Glucose (C6H12O6), molecular weight 180.1559 — NIST Chemistry WebBook
Reviewed
Frequently asked questions
See also
- eGFR Calculator — kidney function from a creatinine result.
- BMI Calculator — BMI, one of the measures NICE PH38 uses to decide who to test.
- Blood Pressure Chart & Checker — a blood pressure reading against the AHA/ACC, NICE and ESC categories.