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A1c to blood sugar chart
Each A1c result matches an estimated average glucose from the American Diabetes Association's ADAG formula and a mmol/mol value from NGSP's master equation. Read across to convert either way: an A1c of 7%, for example, means your blood sugar has averaged about 154 mg/dL (8.6 mmol/L) over the past few months.
| A1c (%) | A1c (mmol/mol) | Average glucose (mg/dL) | Average glucose (mmol/L) | Range |
|---|---|---|---|---|
| 4.0% | 20 | 68 mg/dL | 3.8 mmol/L | Normal |
| 4.5% | 26 | 82 mg/dL | 4.6 mmol/L | Normal |
| 5.0% | 31 | 97 mg/dL | 5.4 mmol/L | Normal |
| 5.5% | 37 | 111 mg/dL | 6.2 mmol/L | Normal |
| 5.7% | 39 | 117 mg/dL | 6.5 mmol/L | Prediabetes (US only) |
| 6.0% | 42 | 126 mg/dL | 7.0 mmol/L | Prediabetes |
| 6.5% | 48 | 140 mg/dL | 7.8 mmol/L | Diabetes range |
| 7.0% | 53 | 154 mg/dL | 8.6 mmol/L | Diabetes range |
| 7.5% | 58 | 169 mg/dL | 9.4 mmol/L | Diabetes range |
| 8.0% | 64 | 183 mg/dL | 10.2 mmol/L | Diabetes range |
| 8.5% | 69 | 197 mg/dL | 10.9 mmol/L | Diabetes range |
| 9.0% | 75 | 212 mg/dL | 11.7 mmol/L | Diabetes range |
| 9.5% | 80 | 226 mg/dL | 12.5 mmol/L | Diabetes range |
| 10.0% | 86 | 240 mg/dL | 13.3 mmol/L | Diabetes range |
| 10.5% | 91 | 255 mg/dL | 14.1 mmol/L | Diabetes range |
| 11.0% | 97 | 269 mg/dL | 14.9 mmol/L | Diabetes range |
| 11.5% | 102 | 283 mg/dL | 15.7 mmol/L | Diabetes range |
| 12.0% | 108 | 298 mg/dL | 16.5 mmol/L | Diabetes range |
| 13.0% | 119 | 326 mg/dL | 18.1 mmol/L | Diabetes range |
| 14.0% | 130 | 355 mg/dL | 19.7 mmol/L | Diabetes range |
Are A1c and blood glucose the same?
No. A blood glucose test, whether a finger-prick, a fasting lab test or a continuous glucose monitor, measures the sugar in your blood at that moment. A1c measures how much of the haemoglobin in your red blood cells has glucose attached, which builds up over the cells' lifespan, so it reflects your average over roughly the past two to three months. Neither is more important: glucose readings show day-to-day swings and lows, and A1c shows the longer trend. Clinicians use both.
The A1c to glucose formula, both ways
| Conversion | Formula |
|---|---|
| A1c (%) → average glucose (mg/dL) | 28.7 × A1c − 46.7 |
| A1c (%) → average glucose (mmol/L) | (28.7 × A1c − 46.7) ÷ 18.016 |
| Average glucose (mg/dL) → A1c (%) | (glucose + 46.7) ÷ 28.7 |
| A1c (%) → mmol/mol | 10.929 × (A1c − 2.15) |
| mmol/mol → A1c (%) | 0.09148 × mmol/mol + 2.152 |
Going from glucose to A1c only makes sense with a true average over weeks, such as a continuous glucose monitor report. Monitors usually show a related figure, the glucose management indicator, which uses a slightly different formula, so it won't always match your lab A1c.
A1c and fasting glucose: why there's no direct conversion
A fasting glucose is one reading after at least 8 hours without food. It's usually lower than your average because it misses the rises after meals, so a fasting result can't be turned into an A1c. Each test has its own cut-offs instead:
| Fasting glucose | Normal | Higher risk (prediabetes) | Diabetes range |
|---|---|---|---|
| US (ADA) | below 100 mg/dL (5.6 mmol/L) | 100–125 mg/dL (5.6–6.9 mmol/L) | 126 mg/dL (7.0 mmol/L) or above |
| UK (NICE) | below 5.5 mmol/L | 5.5–6.9 mmol/L | 7.0 mmol/L or above |
| Canada (Diabetes Canada) | below 6.1 mmol/L | 6.1–6.9 mmol/L | 7.0 mmol/L or above |
Thresholds from the American Diabetes Association, NICE and Diabetes Canada. A result in the diabetes range is confirmed with a repeat test before any diagnosis.
What your A1c means in each country
US labs report A1c as a percentage, UK labs use mmol/mol, and Canadian labs often show both. All three countries treat 6.5% (48 mmol/mol) or above as the diabetes range, confirmed by a repeat test. The prediabetes line differs: the American Diabetes Association uses 5.7%, while NICE in the UK and Diabetes Canada use 6.0% (42 mmol/mol). Our HbA1c guide explains what to do at each level.
How often should you have an A1c test?
If you have diabetes, the American Diabetes Association advises checking at least twice a year, and more often, for example every three months, if you're not meeting your goals or your treatment has recently changed. Because A1c reflects about three months, testing much more often rarely adds anything. If your result is in the prediabetes range, a repeat at least once a year is usual; your clinician will set the schedule.
What to do next
- 5.7% (39) or above: book your GP, family doctor or primary-care clinician and ask about free prevention programmes.
- 6.5% (48) or above: book promptly; a repeat test confirms before any diagnosis.
- Very thirsty, passing a lot of urine or losing weight: get seen the same week, whatever the number.
- Want to check at home? The HbA1c test guide compares free routes and mail-in kits.
Common questions
How do I convert HbA1c from mmol/mol to %?
Multiply the mmol/mol value by 0.09148 and add 2.152, the NGSP master equation. For example, 48 mmol/mol is 6.5%, and 42 mmol/mol is 6.0%. Going the other way, take 2.15 from the percentage and multiply by 10.929. The converter above does both and rounds the way labs do.
What is a normal A1c?
Below 5.7% (39 mmol/mol) is normal in the US, Canada and UK. Between 5.7% and 5.9% is prediabetes in the US but normal under UK and Canadian guidance. From 6.0% to 6.4% (42 to 47 mmol/mol) is prediabetes in all three, and 6.5% (48) or above is the diabetes range.
Are A1c and glucose the same thing?
No. A glucose test measures the sugar in your blood at one moment, while A1c shows the share of haemoglobin with glucose attached, reflecting your average over about two to three months. An A1c of 7% matches an average glucose of about 154 mg/dL (8.6 mmol/L). Clinicians use both because they answer different questions.
Can I convert fasting glucose to A1c?
Not reliably. A fasting reading is a single measurement after not eating, so it's usually lower than your true average and misses the rises after meals. The A1c formula needs an average over weeks, such as a continuous glucose monitor report. Fasting glucose has its own cut-offs, which differ slightly between the US, UK and Canada.
How often should A1c be tested?
For people with diabetes, the American Diabetes Association advises at least twice a year, and about every three months if you're not meeting your goals or your treatment has changed. With a result in the prediabetes range, a repeat at least once a year is usual. Your clinician will set the schedule that fits you.
Can I check my HbA1c at home?
Yes. Mail-in finger-prick kits sent to an accredited lab give a reliable number, though any result in the diabetes range needs confirming by a clinician. In many cases the test is free through a GP, family doctor or as US preventive screening. Our HbA1c guide compares the options and prices.
Sources
- American Diabetes Association. eAG/A1C conversion calculator (ADAG study formula).
- NGSP. IFCC and NGSP HbA1c master equations.
- American Diabetes Association. Standards of Care in Diabetes — 2. Diagnosis and classification. Diabetes Care, 2025;48(Suppl 1).
- American Diabetes Association. Standards of Care in Diabetes — 6. Glycemic goals and hypoglycemia. Diabetes Care, 2025;48(Suppl 1):S128–45.
- NICE. Type 2 diabetes: prevention in people at high risk (PH38).
- Diabetes Canada Clinical Practice Guidelines. Chapter 4: definition, classification and diagnosis.
General information, not medical advice — see our medical disclaimer. These results are estimates and can't diagnose anything. In an emergency, call 911 (US, Canada) or 999 (UK).