HbA1c Conversion Tool
Convert HbA1c between NGSP percentage and IFCC mmol/mol units, with optional estimated average glucose calculation.
Input & Computation
HbA1c reflects cumulative glycaemic exposure over approximately the preceding 8–12 weeks, with greater influence from more recent weeks. Estimated average glucose (eAG) is calculated from HbA1c using a population-derived regression equation. It is not a directly measured glucose value, CGM mean glucose, or glucose management indicator, and may not accurately represent an individual patient’s glucose profile.
Enter Value
All calculations run locally in your browser. No data is transmitted or stored.
Input unit
Interpretation Guide
Conversion Equations
The IFCC equation shown is the precise computational inverse; the commonly quoted rounded form (10.93 × NGSP − 23.50) is an approximation.
Reference Table
| NGSP | IFCC | Approx. eAG |
|---|---|---|
| 5.0% | 31 mmol/mol | 97 mg/dL / 5.4 mmol/L |
| 6.0% | 42 mmol/mol | 126 mg/dL / 7.0 mmol/L |
| 6.5% | 48 mmol/mol | 140 mg/dL / 7.8 mmol/L |
| 7.0% | 53 mmol/mol | 154 mg/dL / 8.6 mmol/L |
| 8.0% | 64 mmol/mol | 183 mg/dL / 10.2 mmol/L |
| 9.0% | 75 mmol/mol | 212 mg/dL / 11.8 mmol/L |
| 10.0% | 86 mmol/mol | 240 mg/dL / 13.4 mmol/L |
Displayed values are rounded.
Evidence & References
Authoritative standardization source for the relationship between NGSP (%) and IFCC (mmol/mol) HbA1c units.
General organization resource covering HbA1c standardization and estimated average glucose. Informational reference, not a formal guideline.
Translating the A1C Assay Into Estimated Average Glucose Values. Diabetes Care 2008;31(8):1473-1478. DOI: 10.2337/dc08-0545. Source of the eAG regression equation.
NGSP(%) = 0.09148 × IFCC(mmol/mol) + 2.152. IFCC(mmol/mol) = (NGSP(%) − 2.152) / 0.09148 (approximately 10.93 × NGSP − 23.50 with rounded coefficients). eAG(mg/dL) = 28.7 × HbA1c(%) − 46.7. eAG(mmol/L) = eAG(mg/dL) / 18. NGSP is used internally as the canonical intermediate for eAG; no intermediate rounding is applied.
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Clinical Laboratory Intelligence Platform
When to Use
- Converting HbA1c between NGSP (%) and IFCC (mmol/mol) reporting units
- Estimating average glucose from a known HbA1c value
- Comparing results reported in different unit systems
- Educational and laboratory reference use
Common Pitfalls
- eAG is a population-derived regression estimate and may not match an individual’s measured glucose
- HbA1c interpretation is affected by altered erythrocyte lifespan, anaemia, haemoglobin variants, and renal disease
- eAG is not the same as fasting glucose, random glucose, CGM mean, or glucose management indicator
- Do not diagnose diabetes from a single HbA1c value — clinical context and guidelines apply