Calculators › Health & Medical
Free calculatorLive resultsSteps and sourcesEmbed on your site, free

A1c Calculator

Converts hemoglobin A1c to estimated average glucose in mg/dL and mmol/L by the ADAG formula, back from glucose to A1c, and between NGSP percent and IFCC mmol/mol, with the ADA classification ranges for information.

Estimated average glucose
154 mg/dL
A1c to Average Glucose (eAG) Calculator
Estimated average glucose
8.6 mmol/L
eAG by the published mmol/L line (secondary)
8.5 mmol/L
A1c (NGSP)
7.0 %
A1c (IFCC)
53 mmol/mol
ADA range (for information, not diagnosis)
In the diabetes range (A1c >= 6.5%, >= 48 mmol/mol)
eAG before rounding
154.200 mg/dL
Regression used
ADAG (Nathan 2008) - ADA/NGSP standard
Worked out from Nathan DM, Kuenen J, Borg R, Zheng H, Schoenfeld D, Heine RJ; A1c-Derived Average Glucose Study Group. Translating the A1C assay into estimated average glucose values. Diabetes Care 2008;31(8):1473-1478 and 7 other sources.
The published mmol/L line gives 8.5 rather than 8.6 mmol/L. The difference is coefficient rounding (1.59 and 2.59 are 28.7/18 and 46.7/18 rounded), not a different model; the published tables agree with 8.6.
The classification is for information only. Diagnosis requires an NGSP-certified assay and confirmatory testing, and the ADA says to use plasma glucose criteria instead where the A1c-glucose relationship is altered: hemoglobin variants, pregnancy (2nd/3rd trimester and postpartum), G6PD deficiency, HIV, hemodialysis, recent blood loss or transfusion, hemolysis, anemia or erythropoietin therapy.
eAG is a population estimate with wide 95% confidence intervals (ADAG: A1c 7% -> 123-185 mg/dL); an individual's true mean glucose can differ substantially.
For information only, not diagnosis. eAG is a population regression with wide confidence intervals (A1c 7% corresponds to 123-185 mg/dL), and the ADA requires an NGSP-certified assay and confirmatory testing before diagnosing diabetes.

Your figures

Updates as you type
The percentage on a US-style report. Values outside 3-20% are rejected as unit mix-ups.
Used in the glucose-to-A1c direction. Accepted range 40-600 mg/dL (2.2-33.3 mmol/L).
The whole-number figure on UK, European and Australian reports (e.g. 53 mmol/mol = 7.0%).
ADAG is what the ADA, NGSP and every current eAG table use. DCCT 2002 is the older type 1-only regression; it gives about 10% higher glucose values.

How this is worked out

6 steps
  1. A1c entered = 7% (NGSP)
  2. eAG (mg/dL) = 28.7 x 7 - 46.7 = 154.2 -> 154 mg/dL
  3. eAG (mmol/L) = 154.2 / 18.0 = 8.5667 -> 8.6 mmol/L (unrounded mg/dL divided by 18.0, which reproduces the published table)
  4. Published mmol/L line for comparison: 1.59 x 7 - 2.59 = 8.5 mmol/L
  5. IFCC = 10.93 x 7 - 23.50 = 53.01 -> 53 mmol/mol
  6. ADA range check on 7%: In the diabetes range (A1c >= 6.5%, >= 48 mmol/mol)

Its 5 worked examples are re-run on every release, last on 15 September 2026. What changed

Sources and references

8 sources
Nathan DM, Kuenen J, Borg R, Zheng H, Schoenfeld D, Heine RJ; A1c-Derived Average Glucose Study Group. Translating the A1C assay into estimated average glucose values. Diabetes Care 2008;31(8):1473-1478
2008 · eAG (mg/dL) = 28.7 x A1C - 46.7, R2 = 0.84; Table 2 footnote eAG (mmol/L) = 1.59 x A1C - 2.59.
American Diabetes Association - eAG/A1C Conversion Calculator
NGSP - IFCC Standardization: NGSP = 0.09148 x IFCC + 2.152; IFCC = 10.93 x NGSP - 23.50; Table 1 (NGSP / IFCC / eAG)
ADA Standards of Care in Diabetes-2025, Section 2: Diagnosis and Classification of Diabetes. Diabetes Care 2025;48(Suppl 1):S27-S49
2025 · A1C >= 6.5% (>= 48 mmol/mol) diabetes; 5.7-6.4% (39-47 mmol/mol) prediabetes; conditions in which A1C is unreliable.
ADA Standards of Care in Diabetes-2026, Section 3 (prediabetes A1C 5.7-6.4%, 39-47 mmol/mol)
2026
ADA Standards of Care in Diabetes-2025, Section 6: Glycemic Goals and Hypoglycemia, Table 6.1 (A1C to eAG with 95% CI)
2025
Rohlfing CL et al. Defining the relationship between plasma glucose and HbA1c: analysis of glucose profiles and HbA1c in the DCCT. Diabetes Care 2002;25(2):275-278
2002 · MPG (mg/dL) = 35.6 x HbA1c - 77.3; MPG (mmol/L) = 1.98 x HbA1c - 4.29; r = 0.82.
NIDDK, Diabetes in America 3rd ed., Conversions: glucose mg/dL x 0.0555 = mmol/L

What this calculator does

Converts hemoglobin A1c to estimated average glucose in mg/dL and mmol/L by the ADAG formula, back from glucose to A1c, and between NGSP percent and IFCC mmol/mol, with the ADA classification ranges for information.

How to use A1c Calculator

Enter Convert, A1c (NGSP / DCCT-aligned), Average glucose, Glucose unit, A1c in IFCC units and Regression. The calculator checks the values, applies the stated method, and updates the result without saving your figures.

What the result means

The result includes Estimated average glucose, Estimated average glucose, eAG by the published mmol/L line (secondary), A1c (NGSP), A1c (IFCC), ADA range (for information, not diagnosis), eAG before rounding and Regression used. Review the visible working and any warnings before using the answer for a decision.

Method and checks

The method cites Nathan DM, Kuenen J, Borg R, Zheng H, Schoenfeld D, Heine RJ; A1c-Derived Average Glucose Study Group. Translating the A1C assay into estimated average glucose values. Diabetes Care 2008;31(8):1473-1478; American Diabetes Association - eAG/A1C Conversion Calculator; NGSP - IFCC Standardization: NGSP = 0.09148 x IFCC + 2.152; IFCC = 10.93 x NGSP - 23.50; Table 1 (NGSP / IFCC / eAG), among others. Its 5 built-in worked examples are checked on every full test run. The initial answer and working are rendered on the server, so they remain readable without JavaScript.

Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.

Embed this calculator on your website

Copy this code into any page. The calculator appears with the figures currently entered, sizes itself to fit, and a small credit line links back here. Free, no account, no ads inside it, no tracking of your readers. Set your own figures and fixed fields; Personal removes the credit line, sets your colour and shows you which sites use it.

Preview

See something wrong? Report a problem with this calculator

Related calculators

Peptide Reconstitution CalculatorHealth & MedicalMap CalculatorHealth & MedicalASCVD Risk CalculatorHealth & MedicaleGFR CalculatorHealth & Medical
View all related calculators4 more
CR Clearance CalculatorHealth & MedicalDosage Infant Tylenol CalculatorHealth & MedicalBody Surface Area CalculatorHealth & MedicalDosage Calculations CalculatorHealth & Medical