HbA1c Unit Converter

Convert HbA1c between % and mmol/mol in either direction. Enter a value and the result updates instantly. This page performs unit conversion and cites where the factor and the reference intervals come from; it does not interpret your value.

mmol/mol

Tracking your HbA1c? See your trend over time and get unit-matched results automatically in the Health3 app.

The HbA1c conversion factor and where it comes from

HbA1c (glycated hemoglobin) reflects average blood glucose over the previous 8 to 12 weeks. HbA1c is reported as a percentage (NGSP/DCCT units) on U.S. and UK reports and in mmol/mol (IFCC units) on most other European reports. Many labs now print both.

The standard conversion factor for HbA1c is the IFCC-NGSP master equation. HbA1c does not use a simple multiplicative factor. The NGSP (%) and IFCC (mmol/mol) scales are linked by the master equation IFCC mmol/mol = 10.929 × (NGSP% − 2.15), equivalently NGSP% = (IFCC ÷ 10.929) + 2.15. Source: IFCC-NGSP master equation (IFCC mmol/mol = 10.929 × (NGSP% − 2.15)).

Published reference intervals

The intervals below are reproduced from U.S. National Library of Medicine, MedlinePlus: Hemoglobin A1C (HbA1c) test. They are listed here for unit reference only. Whether any value is in range for you depends on your laboratory's own reference range and your clinical context, so read them alongside your report and your healthcare provider, not in place of either.

Category	%	mmol/mol
Normal	Below 5.7%	Below 39 mmol/mol
Prediabetes	5.7-6.4%	39-47 mmol/mol
Diabetes	6.5% and above	48 mmol/mol and above

These are ADA diagnostic categories published by the source; a single result is normally confirmed before any diagnosis.

Pre-computed HbA1c conversions

Dedicated answer pages for the HbA1c values people search for most. Each shows the answer, the math, and a table of nearby values.

% to mmol/mol

5.9 % to mmol/mol

mmol/mol to %

Common questions

How do I convert HbA1c from % to mmol/mol?

Use the IFCC-NGSP master equation: mmol/mol = 10.929 × (% − 2.15). For example, 6.5% equals about 48 mmol/mol. The reverse is % = (mmol/mol ÷ 10.929) + 2.15.

Why does HbA1c not have a simple multiplication factor?

The NGSP (%) and IFCC (mmol/mol) scales are anchored differently, so they are related by a linear equation with both a slope (10.929) and an intercept (2.15), not a single multiplier. The converter above applies the full equation in both directions.

Which countries use % and which use mmol/mol?

HbA1c is reported as a percentage (NGSP/DCCT units) on U.S. and UK reports and in mmol/mol (IFCC units) on most other European reports. Many labs now print both.

Related converters and reference

Full blood test unit converter: 60+ biomarkers, any value, either direction.
nmol/L to mg/dL by substance: the molar-to-mass conversion depends on which substance you measured.
HbA1c to average glucose (eAG) converter.
HbA1c to average glucose (eAG) converter.

Medical Disclaimer: This page converts units and cites published reference intervals. It is not a clinical interpretation. Whether any HbA1c value is within range for you depends on your laboratory's reference range, your individual baseline, and clinical context. Discuss specific results with your healthcare provider.

Track HbA1c over time, in either unit system

Health3 imports lab values, converts units automatically, and charts the trend. Free.