acalculator

What does my A1C mean?

Enter your A1C to see your estimated average blood sugar and which CDC range it is in. Or enter an average glucose, or an A1C in mmol/mol, to convert it.

Your numbers

Average glucose (mg/dL)
154

An A1C of 7% means an estimated average glucose of 154 mg/dL (8.6 mmol/L).

Diabetes

  1. Normal
  2. Prediabetes
  3. Diabetes
Average glucose (mmol/L)
8.6
A1C (mmol/mol)
53
Range
Diabetes

Average glucose (mg/dL): 154. An A1C of 7% means an estimated average glucose of 154 mg/dL (8.6 mmol/L).

Where does my A1C fall?

This calculator gives general information only. It is not medical advice and does not replace a doctor or other health care provider. Talk with a professional about your results. Terms of use

How to calculate

Converts an A1C result to estimated average glucose (ADAG equation, mg/dL and mmol/L) and to IFCC mmol/mol, or back, and shows the CDC range: normal, prediabetes, or diabetes.

Example with the default inputs (A1C 7%): An A1C of 7% means an estimated average glucose of 154 mg/dL (8.6 mmol/L).

Formula: eAG (mg/dL) = 28.7 × A1C − 46.7 (ADAG); eAG (mmol/L) = eAG (mg/dL) ÷ 18.0156; A1C (IFCC, mmol/mol) = (A1C − 2.15) ÷ 0.0915.

  • A1C is in NGSP percent units, the unit US labs report.
  • The eAG equation is the average relationship found in the ADAG study; one person’s average glucose can differ from it.
  • Blood loss, transfusion, iron-deficiency anemia, kidney failure, liver disease, and some hemoglobin variants can make an A1C result wrong (NIDDK).
  • The ranges are the CDC’s diagnostic ranges for adults. They are not treatment targets, and this is not medical advice.

Machine-readable copies: Markdown, JSON.

Worked examples

Each example is checked against the calculator on every build.

  1. A1C 6% gives Average glucose (mg/dL) 125.5, Average glucose (mmol/L) 6.966185, A1C (mmol/mol) 42.076503, Range Prediabetes.Source: Nathan and others (2008), ADAG study: eAG = 28.7 × A1C − 46.7, so 6% is 125.5 mg/dL; mmol/L and IFCC by hand in content.mdx; CDC: 5.7% to 6.4% is prediabetes
  2. A1C 7% gives Average glucose (mg/dL) 154.2, Average glucose (mmol/L) 8.559249, Range Diabetes.Source: Nathan and others (2008): 28.7 × 7 − 46.7 = 154.2 mg/dL; CDC: 6.5% or above is the diabetes range
  3. Average glucose (mg/dL) 154 gives A1C 6.993031%.Source: hand calculation in content.mdx: A1C = (154 + 46.7) ÷ 28.7 = 6.99%, the ADAG equation solved for A1C
  4. A1C 5.7% gives A1C (mmol/mol) 38.797814, Average glucose (mg/dL) 116.89, Range Prediabetes.Source: Hoelzel and others (2004): NGSP = 0.0915 × IFCC + 2.15, so 5.7% is (5.7 − 2.15) ÷ 0.0915 = 38.8 mmol/mol; CDC: 5.7% starts the prediabetes range
  5. A1C (mmol/mol) 48 gives A1C 6.542%, Range Diabetes.Source: Hoelzel and others (2004): 0.0915 × 48 + 2.15 = 6.542%; CDC: 6.5% or above is the diabetes range

How A1C is converted

A1C to estimated average glucose (eAG). The A1C-Derived Average Glucose (ADAG) study compared A1C with about 2,700 glucose readings per person over 3 months, in 507 people. The best fit was:

eAG (mg/dL) = 28.7 × A1C − 46.7

with A1C in percent. Solved for A1C: A1C = (eAG + 46.7) ÷ 28.7.

mg/dL to mmol/L. Glucose (C₆H₁₂O₆) has a molar mass of 6 × 12.011 + 12 × 1.008 + 6 × 15.999 = 180.156 g/mol, so 1 mmol/L of glucose is 180.156 mg/L, which is 18.0156 mg/dL:

eAG (mmol/L) = eAG (mg/dL) ÷ 18.0156

Percent to IFCC mmol/mol. The IFCC reference method and the US (NGSP) percent scale are linked by NGSP % = 0.0915 × IFCC + 2.15 (Hoelzel and others, 2004). So:

A1C (mmol/mol) = (A1C % − 2.15) ÷ 0.0915

Fill in any one of the four fields; the calculator finds the other three. A1C can be 3% to 20%; a glucose or mmol/mol value that converts to an A1C outside that range has no answer. No value is rounded in the calculation. The page shows A1C to one decimal, mg/dL and mmol/mol to whole numbers, and mmol/L to one decimal.

CDC ranges, read from the A1C rounded to one decimal, as labs report it:

  • normal: below 5.7% (an unrounded A1C below 5.65%);
  • prediabetes: 5.7% to 6.4% (from 5.65% up to, but not including, 6.45%);
  • diabetes: 6.5% or above (6.45% or above).

So a converted A1C of 6.46%, which the page shows as 6.5%, is in the diabetes range.

Assumptions

  • The eAG equation is an average relationship. For one person, the true average glucose can be higher or lower.
  • A1C can be wrong after recent blood loss or a transfusion, with iron-deficiency anemia, kidney failure, or liver disease, and with some hemoglobin variants (NIDDK).
  • The ranges are for diagnosis in adults, not treatment targets.

This page is for information only. It is not medical advice. Talk with a health care provider about your results.

Worked examples by hand

A1C 6%. eAG = 28.7 × 6 − 46.7 = 172.2 − 46.7 = 125.5 mg/dL (126 when rounded). In mmol/L: 125.5 ÷ 18.0156 = 6.97. In IFCC units: (6 − 2.15) ÷ 0.0915 = 3.85 ÷ 0.0915 = 42.1 mmol/mol. 6% is in the prediabetes range.

A1C 7%. eAG = 28.7 × 7 − 46.7 = 200.9 − 46.7 = 154.2 mg/dL, or 154.2 ÷ 18.0156 = 8.56 mmol/L. 7% is in the diabetes range.

Average glucose 154 mg/dL. A1C = (154 + 46.7) ÷ 28.7 = 200.7 ÷ 28.7 = 6.99%.

A1C 5.7%. IFCC: (5.7 − 2.15) ÷ 0.0915 = 3.55 ÷ 0.0915 = 38.8 mmol/mol. eAG = 28.7 × 5.7 − 46.7 = 163.59 − 46.7 = 116.89 mg/dL. 5.7% is the start of the prediabetes range.

IFCC 48 mmol/mol. A1C = 0.0915 × 48 + 2.15 = 4.392 + 2.15 = 6.542%, in the diabetes range.

Other questions people ask

How do I convert A1C to average blood sugar?

Use the ADAG study equation: estimated average glucose (mg/dL) = 28.7 × A1C − 46.7. An A1C of 7% gives 28.7 × 7 − 46.7 = 154.2 mg/dL. To get mmol/L, divide the mg/dL value by 18.0156: 154.2 ÷ 18.0156 = 8.6 mmol/L.

What A1C level is normal?

The CDC lists an A1C below 5.7% as normal, 5.7% to 6.4% as prediabetes, and 6.5% or above as diabetes. A diagnosis needs a health care provider, usually with a repeat test.

What is A1C in mmol/mol?

Labs outside the US often report A1C in IFCC units, millimoles per mole. The two scales are linked by NGSP % = 0.0915 × IFCC + 2.15 (Hoelzel and others, 2004). So 6.5% is (6.5 − 2.15) ÷ 0.0915 = 47.5, which labs round to 48 mmol/mol.

Why does my meter average not match my A1C?

A1C reflects glucose over about 3 months, while a meter average depends on when you test. People also differ: the ADAG equation is an average, and one person's glucose can sit above or below it. NIDDK notes that recent blood loss, transfusion, iron-deficiency anemia, kidney failure, liver disease, and some hemoglobin variants can make an A1C result wrong.

What is the difference between eAG and GMI?

eAG turns a lab A1C into an average glucose. The glucose management indicator (GMI, Bergenstal and others, 2018) goes the other way: it turns the average glucose from a continuous glucose monitor into an estimated A1C, with its own equation. GMI and a lab A1C often do not agree exactly.

How often should A1C be checked?

That depends on your situation, so ask your health care provider. A1C changes slowly, because it reflects about 3 months of glucose, so a new result usually needs a few months to show a change.