Last updated: May 20, 2026

A1C to Glucose — How to Convert A1C to Average Blood Sugar

Your A1C is a percentage. Your glucose meter shows mg/dL or mmol/L. Here's exactly how to translate between the two — and why it matters.

Quick A1C calculator

Enter your A1C to convert it to estimated average glucose in mg/dL and mmol/L.

HbA1c (%)

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What Does "A1C to eAG" Mean?

When your doctor says your A1C is 7.0%, that number represents the percentage of your hemoglobin that has glucose attached to it. But what does 7.0% actually feel like in terms of daily blood sugar?

That's where eAG (estimated average glucose) comes in. eAG converts your A1C percentage into the same units you see on your glucose meter — mg/dL or mmol/L — so you can directly compare your lab result to your daily readings.

An A1C of 7.0% translates to an eAG of 154 mg/dL (8.6 mmol/L). If your meter has been averaging around 150–160 mg/dL over the past few months, your A1C result makes sense. If there's a big gap, something worth investigating is going on.

Use the A1C to eAG calculator to instantly convert any A1C value to average glucose in both mg/dL and mmol/L.

The Conversion Formula

The standard formula used worldwide for A1C-to-eAG conversion comes from the ADAG (A1C-Derived Average Glucose) study, published in Diabetes Care in 2008:

A1C → eAG

eAG → A1C

These formulas are linear, which means the conversion is straightforward — no complex math required. Or just use the free calculator and skip the arithmetic entirely.

Step-by-Step Conversion Examples

Example 1: A1C of 6.5% → eAG

eAG = 28.7 × 6.5 − 46.7
eAG = 186.55 − 46.7
eAG = 139.9 mg/dL ≈ 140 mg/dL

In mmol/L: 140 ÷ 18.018 = 7.8 mmol/L

This is the diagnostic threshold for diabetes. An A1C of 6.5% means your blood sugar has averaged about 140 mg/dL over the past 2–3 months.

Example 2: A1C of 5.4% → eAG

eAG = 28.7 × 5.4 − 46.7
eAG = 154.98 − 46.7
eAG = 108.3 mg/dL ≈ 108 mg/dL

In mmol/L: 108 ÷ 18.018 = 6.0 mmol/L

Well within the normal range.

Example 3: Average glucose of 183 mg/dL → A1C

A1C = (183 + 46.7) ÷ 28.7
A1C = 229.7 ÷ 28.7
A1C = 8.0%

If your CGM or meter shows a 3-month average around 183 mg/dL, expect your next A1C to be approximately 8.0%.

Quick Reference: A1C to eAG Conversion Table

For the complete table with 0.1% increments, see the full HbA1c chart.

Why Does This Conversion Matter?

1. It Makes Lab Results Understandable

A1C is reported as a percentage — a concept rooted in biochemistry. Most patients don't intuitively understand what "7.2% glycated hemoglobin" means. But "your average blood sugar has been 160 mg/dL" is immediately clear to anyone who checks their glucose.

2. It Connects Lab Work to Daily Monitoring

If your meter averages 145 mg/dL but your lab A1C suggests an eAG of 183 mg/dL, that mismatch is a signal. Possible explanations include:

• You're missing overnight highs (your meter only catches daytime readings)
• Postmeal spikes that resolve before you test
• A medical condition affecting A1C accuracy (see factors that affect A1C accuracy)

3. It Helps You Set Concrete Goals

"Get your A1C below 7%" is abstract. "Keep your average blood sugar under 154 mg/dL" is something you can track every day. The conversion gives you a daily target derived from a quarterly goal.

Where Does This Formula Come From?

The ADAG study (Nathan et al., 2008) enrolled 507 participants across 10 international centers. Participants included people with type 1 diabetes, type 2 diabetes, and people without diabetes. Each wore a continuous glucose monitor for 48 hours per month while also performing daily finger-stick tests.

The resulting formula — eAG = 28.7 × A1C − 46.7 — showed an R² of 0.84, meaning A1C explains 84% of the variation in average glucose. It is now the standard used by the American Diabetes Association, major laboratories, and clinical calculators worldwide.

For the full story behind the research, read ADAG Formula Explained.

Common Questions

Is the conversion exact?

No. The ADAG formula gives a population average. Two people with the same A1C of 7.0% might have actual average glucose values ranging from roughly 123 to 185 mg/dL. The eAG of 154 mg/dL is the best statistical estimate, not a precise measurement.

My CGM average doesn't match my eAG. Why?

Several reasons:

• Biological variation: Your personal A1C-to-glucose relationship may differ from the population average
• CGM coverage: If your CGM wasn't worn continuously, it may miss some highs or lows
• Red blood cell lifespan: Conditions that shorten or extend RBC lifespan shift A1C independently of glucose
• A1C assay interference: Hemoglobin variants can affect certain lab methods

Does the formula work for type 1 and type 2 diabetes?

Yes. The ADAG study specifically included both type 1 and type 2 participants, as well as non-diabetic individuals. The same linear relationship held across all groups.

What about mg/dL vs. mmol/L?

The A1C calculator displays results in both units automatically. If you need to convert manually: 1 mmol/L = 18.018 mg/dL.

Sources

• Nathan DM, Kuenen J, Borg R, Zheng H, Schoenfeld D, Heine RJ. Translating the A1C Assay Into Estimated Average Glucose Values. Diabetes Care. 2008;31(8):1473-1478.
• American Diabetes Association Professional Practice Committee. Glycemic Goals and Hypoglycemia: Standards of Care in Diabetes—2024. Diabetes Care. 2024;47(Suppl 1):S111-S125.
• Diabetes Control and Complications Trial Research Group. The Relationship of Glycemic Exposure (HbA1c) to the Risk of Development and Progression of Retinopathy in the Diabetes Control and Complications Trial. Diabetes. 1995;44(8):968-983.

This article is for informational purposes only and does not constitute medical advice. Consult your healthcare provider for interpretation of your results.