HbA1c and average glucose conversion
Estimated average glucose over about 2–3 months from laboratory HbA1c, or an approximate reverse estimate.
- Free
- No registration
Calculation
This calculation is for reference only and is not medical advice, a diagnosis or a prescription. If you have a medical condition, are pregnant, take medication or have any doubts, discuss the result with a physician or a qualified nutrition professional.
Result
- Estimated average glucose (eAG)
- 6.3 mmol/L (114 mg/dL)
- HbA1c
- 5.6 % (38 mmol/mol)
- Interpretation
- HbA1c < 5.7%
Estimated average glucose over 2–3 months, not a single or fasting glucose reading.
A reverse estimate from average glucose does not replace an HbA1c test or establish a diagnosis. Anaemia, altered red-cell lifespan, haemoglobin variants and pregnancy can affect the relationship. Diagnostic conclusions require clinical assessment and usually repeat confirmation.
A reverse estimate from average glucose does not replace an HbA1c test or establish a diagnosis. Anaemia, altered red-cell lifespan, haemoglobin variants and pregnancy can affect the relationship. Diagnostic conclusions require clinical assessment and usually repeat confirmation. Estimated average glucose over 2–3 months, not a single or fasting glucose reading. Reference ranges are population benchmarks from the cited sources. Laboratories use their own ranges, and interpretation depends on clinical context: discuss the result with your physician.
How it is calculated
The ADAG relationship is a population-based estimate, not an exact match for every individual. NGSP/IFCC conversion uses the official master equation.
Formula
eAG (mg/dL) = 28.7 × HbA1c (%) − 46.7; eAG (mmol/L) = eAG (mg/dL) / 18.016; IFCC (mmol/mol) = (NGSP (%) − 2.152) / 0.09148; NGSP (%) = 0.09148 × IFCC + 2.152.
Limits of the method
A reverse estimate from average glucose does not replace an HbA1c test or establish a diagnosis. Anaemia, altered red-cell lifespan, haemoglobin variants and pregnancy can affect the relationship. Diagnostic conclusions require clinical assessment and usually repeat confirmation.
Sources of the method
- Nathan DM et al. Translating the A1C assay into estimated average glucose values. Diabetes Care, 2008
- American Diabetes Association Professional Practice Committee. et al. 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes-2024. Diabetes Care, 2024
- NGSP. IFCC Standardization of HbA1c: master equation NGSP ↔ IFCC
How to use the calculation
Enter the starting values
Use actual values and the appropriate units.
Adjust the parameters
Adjust the starting assumptions for your situation.
Read the result
Consider the model limitations; a calculation is not a measurement.
Frequently asked questions
What does the calculation show?
Estimated average glucose over about 2–3 months from laboratory HbA1c, or an approximate reverse estimate. The ADAG relationship is a population-based estimate, not an exact match for every individual. NGSP/IFCC conversion uses the official master equation.
What limitations apply?
A reverse estimate from average glucose does not replace an HbA1c test or establish a diagnosis. Anaemia, altered red-cell lifespan, haemoglobin variants and pregnancy can affect the relationship. Diagnostic conclusions require clinical assessment and usually repeat confirmation. Estimated average glucose over 2–3 months, not a single or fasting glucose reading.
Related calculators
Related tools.
Other calculators
Lab tests and metabolic health
- Diet and lifestyle checklist
- HOMA-IR Calculator: Insulin Resistance Index
- TyG Index Calculator (Triglycerides × Glucose)
- Lipid profile: calculated measures
- eGFR Calculator (CKD-EPI 2021)
- Lab Unit Converter
- Vitamin D: van Groningen model estimate
- Iron Deficiency Calculator: TSAT, Ferritin and Ganzoni Deficit
- PhenoAge Biological Age Calculator (Levine)
- FIB-4 and APRI Calculator: Liver Fibrosis Indices
- Vermeulen free testosterone estimate
- Anion Gap and Delta Ratio Calculator
- Albumin-Corrected Calcium Calculator