A1c to Average Glucose Calculator

Convert HbA1c between percentage, mmol/mol and estimated average glucose.

About A1c to Average Glucose Calculator

HbA1c reflects average glucose over the red cell lifespan, so it lags recent changes by weeks. The two reporting units express the same measurement and convert linearly. HbA1c can be misleading where red cell turnover is abnormal, such as in anaemia or pregnancy, which is why it is interpreted alongside direct glucose measurement.

Formula

A1c to Average Glucose

eAG (mg/dL) = 28.7 × A1c − 46.7; IFCC (mmol/mol) = (A1c − 2.15) × 10.929

HbA1c: Glycated haemoglobin, reflecting average glucose over roughly three months
IFCC: The international standard unit, mmol per mol of haemoglobin

Worked example

With the default values below, A1c to Average Glucose Calculator returns Estimated Average Glucose of 8.877. Change any input above and every figure here is recalculated in your browser.

Inputs used

HbA1caccepts 3–20 %: 7.2 %

Results

Estimated Average Glucose: 8.877 mmol/L
Estimated Average Glucose: 159.9 mg/dL
HbA1c in IFCC Units: 55.2 mmol/mol
Reference Band: Above the diabetes threshold, near common treatment targets
Change Needed to Reach 7 Per Cent: 0.20 %

Step by step

1Values used
2A1c to Average Glucose
3Estimated Average Glucose= 8.877 mmol/L
4Estimated Average Glucose= 159.9 mg/dL
5HbA1c in IFCC Units= 55.2 mmol/mol
6Reference Band= Above the diabetes threshold, near common treatment targets
7Change Needed to Reach 7 Per Cent= 0.20 %

Assumptions and limits

The result is derived only from the single input listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
This reproduces a published formula for educational and reference use only. It is not a diagnostic tool, does not account for individual clinical context, and must not be used to make or change treatment decisions. Clinical assessment by a qualified healthcare professional is always required. Reference bands quoted here are general and vary between guidelines and laboratories. Interpretation of HbA1c requires clinical context and must be done by a healthcare professional.
This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

This reproduces a published formula for educational and reference use only. It is not a diagnostic tool, does not account for individual clinical context, and must not be used to make or change treatment decisions. Clinical assessment by a qualified healthcare professional is always required. Reference bands quoted here are general and vary between guidelines and laboratories. Interpretation of HbA1c requires clinical context and must be done by a healthcare professional.

Frequently Asked Questions

How is A1c to Average Glucose calculated?

eAG (mg/dL) = 28.7 × A1c − 46.7; IFCC (mmol/mol) = (A1c − 2.15) × 10.929 HbA1c reflects average glucose over the red cell lifespan, so it lags recent changes by weeks. The two reporting units express the same measurement and convert linearly.

Why does A1c to Average Glucose matter?

HbA1c can be misleading where red cell turnover is abnormal, such as in anaemia or pregnancy, which is why it is interpreted alongside direct glucose measurement.

What values do I need to enter?

This calculator takes 1 input: HbA1c. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.