A1C Calculator
Convert A1C to estimated average glucose and back with the ADAG equation, in mg/dL, mmol/L and IFCC mmol/mol, plus a full A1C chart from 4% to 14%.
A1C Calculator: with the default inputs, result is 154.
Your HbA1c result as a percentage (the NGSP/DCCT unit US labs report). Used when converting from A1C.
A meter or CGM average over about three months. Used when converting from average glucose.
Average glucose in your chosen unit, or A1C in %, depending on the direction.
- In words
- An A1C of 7% corresponds to an estimated average glucose of 154 mg/dL (8.6 mmol/L).
- A1C (NGSP)
- 7%
- Estimated average glucose (mg/dL)
- 154
- Estimated average glucose (mmol/L)
- 8.6
- A1C (IFCC, mmol/mol)
- 53
- ADA diagnostic range
- Diabetes range (6.5% or higher)
Assumptions
- This is an estimate for education. It does not diagnose diabetes or prediabetes and does not replace your clinician or a laboratory test.
- Average glucose is the ADAG regression (eAG = 28.7 × A1C − 46.7). It describes a population average; an individual's true average glucose can differ by 30 mg/dL or more at the same A1C.
- Glucose is converted at 18.016 mg/dL per mmol/L (molar mass 180.16 g/mol).
- IFCC values use the NGSP-IFCC master equation, NGSP = 0.09148 × IFCC + 2.152.
- Diagnostic ranges are the ADA's for non-pregnant adults. A1C is unreliable with anemia, hemoglobin variants, recent transfusion, pregnancy and advanced kidney disease.
| A1C (%) | eAG (mg/dL) | eAG (mmol/L) | IFCC (mmol/mol) | ADA range |
|---|---|---|---|---|
| 4 | 68 | 3.8 | 20 | Normal |
| 4.5 | 82 | 4.6 | 26 | Normal |
| 5 | 97 | 5.4 | 31 | Normal |
| 5.5 | 111 | 6.2 | 37 | Normal |
| 6 | 126 | 7 | 42 | Prediabetes |
| 6.5 | 140 | 7.8 | 48 | Diabetes range |
| 7 | 154 | 8.6 | 53 | Diabetes range |
| 7.5 | 169 | 9.4 | 58 | Diabetes range |
| 8 | 183 | 10.2 | 64 | Diabetes range |
| 8.5 | 197 | 10.9 | 69 | Diabetes range |
| 9 | 212 | 11.7 | 75 | Diabetes range |
| 9.5 | 226 | 12.5 | 80 | Diabetes range |
| 10 | 240 | 13.3 | 86 | Diabetes range |
| 10.5 | 255 | 14.1 | 91 | Diabetes range |
| 11 | 269 | 14.9 | 97 | Diabetes range |
| 11.5 | 283 | 15.7 | 102 | Diabetes range |
| 12 | 298 | 16.5 | 108 | Diabetes range |
| 12.5 | 312 | 17.3 | 113 | Diabetes range |
| 13 | 326 | 18.1 | 119 | Diabetes range |
| 13.5 | 341 | 18.9 | 124 | Diabetes range |
| 14 | 355 | 19.7 | 130 | Diabetes range |
eAG from the ADAG equation (Nathan et al. 2008); IFCC from the NGSP-IFCC master equation; ranges from the American Diabetes Association.
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How this is worked out
The formula
eAG (mg/dL) = 28.7 × A1C − 46.7 A1C (%) = (eAG (mg/dL) + 46.7) ÷ 28.7 eAG (mmol/L) = eAG (mg/dL) ÷ 18.016 IFCC (mmol/mol) = (A1C − 2.152) ÷ 0.09148 [NGSP = 0.09148 × IFCC + 2.152] A1C = hemoglobin A1C in NGSP/DCCT percent eAG = estimated average glucose over roughly the previous 2–3 months ADA: under 5.7% normal · 5.7–6.4% prediabetes · 6.5% or higher diabetes
Open How it’s calculated above to see this worked through with your own numbers.
What you enter
- Convert
- Choose one of 2 options.A1C → average glucose · Average glucose → A1C
- A1C
- Your HbA1c result as a percentage (the NGSP/DCCT unit US labs report). Used when converting from A1C.from 3 to 20 · defaults to 7
- Average glucose
- A meter or CGM average over about three months. Used when converting from average glucose.from 1 to 700 · defaults to 154
- Glucose unit
- Choose one of 2 options.mg/dL (US) · mmol/L
What you get back
- Resultmain answer
- Average glucose in your chosen unit, or A1C in %, depending on the direction.
- In words
- A1C (NGSP)
- Estimated average glucose (mg/dL)
- Estimated average glucose (mmol/L)
- A1C (IFCC, mmol/mol)
- ADA diagnostic range
What this assumes
- This is an estimate for education. It does not diagnose diabetes or prediabetes and does not replace your clinician or a laboratory test.
- Average glucose is the ADAG regression (eAG = 28.7 × A1C − 46.7). It describes a population average; an individual's true average glucose can differ by 30 mg/dL or more at the same A1C.
- Glucose is converted at 18.016 mg/dL per mmol/L (molar mass 180.16 g/mol).
- IFCC values use the NGSP-IFCC master equation, NGSP = 0.09148 × IFCC + 2.152.
- Diagnostic ranges are the ADA's for non-pregnant adults. A1C is unreliable with anemia, hemoglobin variants, recent transfusion, pregnancy and advanced kidney disease.
About this calculator
Your A1C (HbA1c) is the share of hemoglobin in your red blood cells that has glucose attached. Because red cells live about three months, it reflects your average blood sugar over that stretch rather than any single reading. This calculator converts that percentage into the estimated average glucose (eAG) you would recognise from a meter, in mg/dL or mmol/L, and works the other way too: give it an average from your meter or CGM and it estimates the A1C that goes with it. It also gives the IFCC value in mmol/mol, the unit labs in the UK, Europe and Australia report.
Where the conversion comes from
The relationship is the ADAG equation, eAG = 28.7 × A1C − 46.7, from the A1C-Derived Average Glucose study (Nathan et al., Diabetes Care, 2008). Researchers compared A1C with continuous glucose monitoring and frequent finger sticks in about 500 people with and without diabetes, and the American Diabetes Association adopted the equation for reporting eAG. Each 1-point change in A1C is about 29 mg/dL (1.6 mmol/L) of average glucose. The IFCC conversion uses the NGSP master equation that links the two standardised assays.
How to use it
Pick a direction. For A1C → average glucose, enter your lab result; for average glucose → A1C, enter your meter or CGM average and choose mg/dL or mmol/L. The result, the other units and the ADA range all update together.
The A1C chart
Below the result is a full A1C chart — A1C from 4% to 14% in half-point steps, with the matching average glucose in both units, the IFCC value and the ADA diagnostic range. It is the same A1C conversion chart printed in clinic handouts, computed from the equation rather than copied, so every row agrees with the calculator.
Reading the result
The American Diabetes Association uses three diagnostic ranges: below 5.7% is normal, 5.7% to 6.4% is prediabetes, and 6.5% or higher is in the diabetes range. A diagnosis needs a lab test, and usually a confirming repeat, not a calculator. For most adults with diabetes the ADA suggests a target of about 7% (eAG 154 mg/dL), but targets are set individually.
Caveats
The equation describes the average person in the study. At any given A1C, real average glucose varies: the ADAG paper's 95% interval at 7% runs roughly from 123 to 185 mg/dL. A1C also reads falsely high or low with anemia, recent blood loss or transfusion, hemoglobin variants, pregnancy and advanced kidney disease. If your CGM's glucose management indicator and your lab A1C disagree, that gap is real information to discuss with your clinician, not a calculation error.
Frequently asked questions
▸What average blood sugar is an A1C of 7%?
About 154 mg/dL (8.6 mmol/L), from the ADAG equation 28.7 × 7 − 46.7. Each point of A1C above or below that is roughly 29 mg/dL.
▸What is a normal A1C?
Below 5.7%, according to the American Diabetes Association. From 5.7% to 6.4% is prediabetes, and 6.5% or higher on a lab test is in the diabetes range.
▸How do I convert average glucose to A1C?
Reverse the ADAG equation: A1C = (average glucose in mg/dL + 46.7) ÷ 28.7. An average of 126 mg/dL gives 6.0%. For mmol/L, multiply by 18 first.
▸How do I convert A1C percent to mmol/mol?
Use the NGSP-IFCC master equation: mmol/mol = (A1C − 2.152) ÷ 0.09148. 6.5% is 48 mmol/mol and 7% is 53 mmol/mol.
▸Why doesn't my meter average match my A1C?
A meter average is weighted toward the times you test, often before meals, while A1C reflects every hour of the day. Red-cell lifespan, anemia and hemoglobin variants also shift A1C, so a gap of 10–20 mg/dL is common.
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