Blood Sugar / HbA1c Converter

Convert HbA1c (NGSP % ↔ IFCC mmol/mol) and estimated average glucose (eAG). Private by design—everything runs locally in your browser.

Enter any one value

Percent as typically reported in UK/US labs.
IFCC units as reported in mmol/mol.
Estimated average glucose (eAG) in mg/dL.
Estimated average glucose (eAG) in mmol/L.

Tip: Type in any one box—everything else updates automatically. Press Esc to clear the focused field.

Converted values

HbA1c (NGSP)—
HbA1c (IFCC)—
eAG (mg/dL)—
eAG (mmol/L)—

Rounding: A1c to 1 dp (NGSP) / 0 dp (IFCC), glucose to nearest 1 mg/dL / 0.1 mmol/L.

About the equations

The relationship between HbA1c and blood glucose has been studied extensively to help people and clinicians interpret lab values in a practical way. HbA1c, sometimes called “glycated hemoglobin,” reflects how much sugar has attached to red blood cells over their lifespan. Because red blood cells live around three months, HbA1c provides an average picture of glucose control over the past 8–12 weeks, with recent weeks weighing more heavily.

To translate HbA1c into a more familiar blood sugar number, researchers developed the ADAG (A1c-Derived Average Glucose) equations. These formulas estimate the average glucose level that corresponds to a given HbA1c:

  • A1c → eAG: eAG (mg/dL) = 28.7 × A1c(%) − 46.7
  • A1c → eAG: eAG (mmol/L) = 1.59 × A1c(%) − 2.59
  • Inverse (eAG → A1c): A1c(%) = (eAGmg/dL + 46.7) ÷ 28.7
  • Inverse (eAG → A1c): A1c(%) = (eAGmmol/L + 2.59) ÷ 1.59
  • Units: 1 mmol/L = 18 mg/dL

In addition to average glucose, HbA1c can be expressed in two different laboratory standards. The NGSP system (most common in the US and UK) reports HbA1c as a percentage, while the IFCC standard (widely used internationally) reports it in mmol/mol. The two can be converted using:

  • NGSP(%) = 0.0915 × IFCC (mmol/mol) + 2.15
  • IFCC (mmol/mol) = 10.929 × (NGSP − 2.15)

These conversions are helpful because many online resources, research papers, and clinics may report results in different units. With a converter, you can quickly move between NGSP %, IFCC mmol/mol, and estimated average glucose in either mg/dL or mmol/L. This makes it easier to compare your results with educational materials, scientific studies, or glucose targets set by health guidelines.

Important disclaimer: The eAG values are statistical estimates. Individual results may vary due to conditions such as anemia, hemoglobin variants, kidney or liver disease, pregnancy, or certain medications. Continuous glucose monitors (CGM) or home blood glucose meters may show numbers that differ from the calculated eAG. Always interpret HbA1c and glucose values in consultation with your healthcare professional.

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