BYTETOOLS

A1C Calculator

Convert HbA1c to estimated average glucose and back using the ADAG equation, in mg/dL and mmol/L, with IFCC units and ADA reference bands.

Result

6.5% HbA1c  ≈  140 mg/dL (7.8 mmol/L)

eAG = 28.7 × 6.5 − 46.7 = 139.8 mg/dL

Diabetes rangeThe ADA diagnostic threshold for diabetes is an HbA1c of 6.5% or above, confirmed on a repeat test.
6.5%
HbA1c (DCCT %)
48 mmol/mol
HbA1c (IFCC)
140 mg/dL
eAG
7.8 mmol/L
eAG

ADAG conversion table

HbA1c (%)IFCC (mmol/mol)eAG (mg/dL)eAG (mmol/L)ADA band
5.031975.4Normal
5.5371116.2Normal
6.0421257.0Prediabetes
6.5481407.8Diabetes
7.0531548.6Diabetes
7.5581699.4Diabetes
8.06418310.2Diabetes
8.56919710.9Diabetes
9.07521211.7Diabetes
10.08624013.3Diabetes
11.09726914.9Diabetes
12.010829816.5Diabetes

Conversion uses the ADAG regression published by Nathan et al. in Diabetes Care (2008): eAG (mg/dL) = 28.7 × A1C − 46.7. The IFCC column uses the master equation IFCC = (DCCT − 2.15) × 10.929. Bands are the American Diabetes Association thresholds (normal < 5.7%, prediabetes 5.7–6.4%, diabetes ≥ 6.5%); other countries and guidelines draw them slightly differently.

This tool converts numbers — it does not diagnose diabetes, prediabetes or anything else, and it is not medical advice. The ADAG equation is a regression through 507 participants and individual results scatter around it: the published 95% confidence interval at an A1C of 7% is roughly 123–185 mg/dL, so your true average glucose can sit well away from the single number shown. Anaemia, kidney disease, pregnancy, haemoglobin variants, recent transfusion and a shortened red-cell lifespan all make HbA1c unreliable. Discuss any result with your doctor, and never change a medication dose based on a web calculator.

What is the A1C Calculator?

An A1C calculator converts HbA1c to estimated average glucose with the ADAG equation, eAG in mg/dL = 28.7 × A1C − 46.7. An HbA1c of 7% corresponds to an eAG of about 154 mg/dL, or 8.6 mmol/L.

  • Two-way conversion between HbA1c and estimated average glucose
  • ADAG equation named and shown, so results are auditable
  • mg/dL, mmol/L and IFCC mmol/mol in one place
  • ADA reference bands for normal, prediabetes and diabetes ranges
  • Full conversion table from 5% to 12% with your value highlighted
  • Entirely offline — your health numbers never leave the browser

How to use the A1C Calculator

  1. 1

    Choose which direction you want to convert.

  2. 2

    Pick mg/dL or mmol/L to match your meter or lab report.

  3. 3

    Enter your HbA1c percentage, or your average glucose reading.

  4. 4

    Read the converted value along with the IFCC mmol/mol equivalent.

  5. 5

    Check the reference table to see where your value sits against neighbouring ones.

About the A1C Calculator

The ByteTools A1C Calculator converts between HbA1c and estimated average glucose in both directions. It uses the ADAG regression published by Nathan and colleagues in Diabetes Care in 2008 — eAG in mg/dL = 28.7 × A1C − 46.7 — and shows the result in mg/dL, mmol/L and IFCC mmol/mol so it matches whichever units your lab report uses.

Enter an HbA1c percentage to see the average glucose it implies, or enter a meter or CGM average to see the HbA1c it corresponds to. Results are banded against the American Diabetes Association reference ranges — under 5.7% normal, 5.7 to 6.4% prediabetes, 6.5% and above the diabetes threshold — and a full conversion table lets you read off neighbouring values.

Everything is computed in your browser and nothing is uploaded or stored. This tool converts numbers; it does not diagnose diabetes or anything else, and it is not medical advice. Individual results scatter widely around the ADAG regression, and several common conditions make HbA1c unreliable altogether, so discuss any result with your doctor and never change a medication dose based on a web calculator.

Frequently asked questions

What is an A1C of 7 in average glucose?

About 154 mg/dL, which is 8.6 mmol/L. That comes from the ADAG equation, eAG = 28.7 × 7 − 46.7 = 154.2 mg/dL, and it matches the figure in the American Diabetes Association's published conversion table.

How accurate is the A1C to average glucose conversion?

The equation is a regression line through 507 study participants, and individuals scatter around it considerably. At an HbA1c of 7% the published 95% confidence interval for average glucose runs from roughly 123 to 185 mg/dL. So the single number this tool shows is the centre of a fairly wide range, not a precise reading of your blood.

What HbA1c level is diabetes?

The American Diabetes Association sets the diagnostic threshold at 6.5% or above, confirmed on a repeat test, with 5.7 to 6.4% classed as prediabetes and below 5.7% as normal. Diagnosis is a clinical decision made by a doctor using more than one number — a calculator cannot make it.

Why is my meter average different from my A1C?

Several reasons. HbA1c reflects roughly the last two to three months and is weighted towards the most recent weeks, while a meter average only covers the readings you actually took — and people tend to test at particular times of day. Red-cell lifespan also varies between individuals, which shifts HbA1c up or down independently of glucose.

When is HbA1c unreliable?

Anaemia, recent blood transfusion, chronic kidney disease, pregnancy, haemoglobin variants such as sickle cell trait, and anything that shortens red-cell survival can all make HbA1c read falsely high or low. In those situations a clinician will usually rely on a different test.

What is the difference between DCCT % and IFCC mmol/mol?

They are two ways of reporting the same measurement. The DCCT/NGSP percentage is standard in the United States, while IFCC mmol/mol is used across much of Europe. They convert with IFCC = (DCCT − 2.15) × 10.929, so 7% is 53 mmol/mol. This tool shows both.

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