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A1C Calculator

Convert A1C to estimated average glucose or estimated average glucose to A1C using the ADA/ADAG relationship.

  • hba1c
  • hemoglobin a1c
  • eag
  • estimated average glucose
  • blood sugar average

Enter A1C as a percentage, such as 7.

Used when converting IFCC mmol/mol to A1C percentage.

Used when converting eAG to A1C.

Status: initial

Results

Awaiting calculation

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A1C reference context

Explore the a1c calculator result visually while keeping this page's detailed guidance and examples.

A1C reference context
6.2%
LowerTypicalPrediabetesDiabetesHigher

Use this result well

  1. 1Verify the calculator inputs.
  2. 2Compare the key result relationships.
  3. 3Review the page guidance before acting.

Use A1C as a screening or monitoring estimate with qualified medical guidance.

Calculator guide

Introduction

The A1C Calculator converts between A1C percentage and estimated average glucose, also called eAG, using the widely cited ADAG relationship.

Purpose

Use this tool to understand how a lab-reported A1C may correspond to an estimated average glucose number, how an average glucose estimate may convert back to A1C, or how HbA1c IFCC mmol/mol maps to A1C percentage.

How A1C and eAG are related

The American Diabetes Association describes the estimated average glucose relationship as eAG mg/dL = 28.7 x A1C - 46.7. The reverse formula solves that equation for A1C.

Variable explanations

Understand what each input and result means before calculating.

A1C percentage

A lab-reported percentage reflecting glycated hemoglobin.

Estimated average glucose

A calculated estimate intended to be easier to compare with glucose meter units.

HbA1c IFCC

A mmol/mol HbA1c value used by many international laboratories and converted here to A1C percent.

mg/dL

Milligrams per deciliter, common in the United States.

mmol/L

Millimoles per liter, common in many other countries.

Range label

A general educational label, not a diagnosis.

Reviewed by the Calculator.org.in Editorial Team

Formula behavior, validation cases, explanatory examples, and cited sources are checked before publication. This review supports educational accuracy and is not a substitute for qualified professional advice.

Last reviewed: 2026-07-05

Review process

Formula guide

See the calculation logic, variable definitions, and practical meaning.

A1C to eAG

eAG mg/dL = 28.7 x A1C - 46.7

  • A1C is entered as a percent.
  • eAG is estimated average glucose.

This estimates average glucose in the same mg/dL unit used by many glucose meters.

eAG to A1C

A1C = (eAG mg/dL + 46.7) / 28.7

  • eAG must be in mg/dL before the reverse formula.

If eAG is entered in mmol/L, the calculator first converts it to mg/dL.

IFCC mmol/mol to A1C

A1C = IFCC mmol/mol / 10.929 + 2.15

  • IFCC mmol/mol is the HbA1c unit used by many labs outside the United States.

This converts the IFCC HbA1c unit to the DCCT/NGSP-style percentage shown by many A1C resources.

A1C to IFCC mmol/mol

IFCC mmol/mol = 10.929 x (A1C - 2.15)

  • A1C is entered as a percent.

The calculator displays IFCC mmol/mol alongside eAG for easier lab comparison.

mg/dL to mmol/L

mmol/L = mg/dL / 18.015

  • The conversion factor is for glucose.

This lets the result display both common glucose units.

Worked examples

Follow realistic inputs through the calculation step by step.

1

Worked example

A1C 7%

  1. 1Enter 7 as A1C.
  2. 2Calculate.
  3. 3Review eAG near 154 mg/dL.
2

Worked example

A1C 6.5%

  1. 1Enter 6.5.
  2. 2Calculate.
  3. 3Review eAG near 140 mg/dL.
3

Worked example

eAG 154 mg/dL

  1. 1Choose eAG to A1C.
  2. 2Enter 154 mg/dL.
  3. 3Review A1C near 7%.
4

Worked example

IFCC 53 mmol/mol

  1. 1Choose HbA1c IFCC mmol/mol to A1C.
  2. 2Enter 53.
  3. 3Review A1C near 7% and compare the eAG result.
5

Worked example

mmol/L result

  1. 1Calculate from A1C.
  2. 2Review both mg/dL and mmol/L outputs.
  3. 3Discuss lab results with a clinician.

Common mistakes

Avoid these common input and interpretation errors.

Treating eAG as a meter average

eAG is calculated from A1C and may not match fingerstick or CGM averages exactly.

Using the calculator for diagnosis

Diagnosis requires appropriate clinical testing and interpretation.

Ignoring individual targets

A1C goals vary by person, age, pregnancy status, health conditions, and clinician guidance.

Mixing glucose units

mg/dL and mmol/L are different units and must be converted correctly.

Mixing A1C percent and IFCC mmol/mol

A1C percent and HbA1c IFCC mmol/mol are different reporting systems, so enter each value in the matching field.

Frequently asked questions

Quick answers to the questions users ask most often.

What does this A1C Calculator calculate?
It converts A1C to estimated average glucose and estimated average glucose to A1C.
What formula is used?
The calculator uses eAG mg/dL = 28.7 x A1C - 46.7 and the reverse formula A1C = (eAG + 46.7) / 28.7.
What is A1C?
A1C is a blood test result reported as a percentage that reflects average blood glucose over roughly the past two to three months.
What is eAG?
eAG means estimated average glucose. It converts A1C into glucose units such as mg/dL or mmol/L.
Is eAG the same as my meter average?
No. eAG is calculated from A1C and may differ from fingerstick or CGM averages.
Can this diagnose diabetes?
No. Diagnosis requires clinical testing and interpretation by a qualified healthcare professional.
What A1C range is commonly considered normal?
Public health references commonly describe below 5.7% as below the prediabetes threshold.
What A1C range is commonly called prediabetes?
Public health references commonly describe 5.7% to 6.4% as the prediabetes range.
What A1C is commonly associated with diabetes?
Public health references commonly describe 6.5% or above as the diabetes threshold, but diagnosis requires clinical evaluation.
Can A1C be inaccurate?
Yes. Conditions affecting red blood cells, hemoglobin variants, pregnancy, kidney disease, and other factors can affect A1C interpretation.
Does this calculator set my target?
No. A1C targets are individualized and should be discussed with a clinician.
Does this replace glucose monitoring?
No. A1C and eAG do not replace glucose monitoring recommended by a healthcare professional.
Can I enter mmol/L?
Yes. Choose mmol/L when converting estimated average glucose to A1C.
Can I convert HbA1c mmol/mol to A1C percent?
Yes. Choose the HbA1c IFCC mmol/mol to A1C mode and enter the mmol/mol value from the lab report.
What is the difference between A1C percent and IFCC mmol/mol?
They are two reporting systems for HbA1c. A1C percent is common in the United States, while IFCC mmol/mol is common in many other countries.
Why does 7% A1C show about 154 mg/dL?
Using the formula 28.7 x 7 - 46.7 gives 154.2 mg/dL.
Is this medical advice?
No. It is an educational conversion calculator only.

References

Sources used to support the calculator guidance.

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Version history

A transparent record of calculator content updates.

Updated 2026-07-05
  • 1.0.0 · 2026-07-05

    Initial A1C and eAG conversion calculator release.