A1C of 6.7% is an average glucose of 146 mg/dL

Estimated average glucose at A1C 6.7%

146 mg/dL

In mmol/L: 8.1 mmol/L
A1C entered: 6.7%
ADA range: the range the ADA uses to diagnose diabetes

An A1C of 6.7% corresponds to an estimated average glucose of 146 mg/dL, or 8.1 mmol/L, across roughly the previous two to three months. In IFCC units that A1C is about 50 mmol/mol.

The ADA uses 6.5% and above as one of its diagnostic criteria for diabetes, and normally asks for a confirmatory test before diagnosing. What that means for you is a conversation for your clinician, not for a calculator.

One tenth higher, at 6.8%, the estimate reaches about 148 mg/dL — a difference of roughly 2 mg/dL. Set against the 0.5 percentage points a certified assay may vary by, that is a very small step indeed.

Bringing the printed report to an appointment beats bringing a screenshot of a calculator, because your clinician can read it against everything else in your chart.

Comparing an older report against a newer one sometimes means comparing units as well as values — a percentage against mmol/mol, or mg/dL against mmol/L. Convert before concluding anything.

Ancestry-linked haemoglobin variants can interfere with certain assay methods specifically, which is a reason a result that looks inconsistent with everything else is worth raising rather than accepting.

Two numbers can be identical and describe quite different weeks. That is not a flaw in the measurement so much as a limit of what any average can say.

Convert a different A1C value

A1C to estimated average glucose, 6.2% to 7.2%
A1C	eAG (mg/dL)	eAG (mmol/L)
6.2%	131 mg/dL	7.3 mmol/L
6.3%	134 mg/dL	7.4 mmol/L
6.4%	137 mg/dL	7.6 mmol/L
6.5%	140 mg/dL	7.8 mmol/L
6.6%	143 mg/dL	7.9 mmol/L
6.7%	146 mg/dL	8.1 mmol/L
6.8%	148 mg/dL	8.2 mmol/L
6.9%	151 mg/dL	8.4 mmol/L
7.0%	154 mg/dL	8.5 mmol/L
7.1%	157 mg/dL	8.7 mmol/L
7.2%	160 mg/dL	8.9 mmol/L

Computed with eAG (mg/dL) = 28.7 x A1C - 46.7 (Nathan 2008). mmol/L is derived from mg/dL using the glucose factor 18.0182.

Estimated average glucose (ADAG / Nathan) — eAG (mg/dL) = 28.7 x A1C - 46.7. Verified 2026-07-30 against Nathan et al., Diabetes Care 2008 (ADAG study) (A population regression: in the ADAG study, individuals at the same A1C had meaningfully different mean glucose. The A1C assay itself carries about +/- 0.5 percentage points under NGSP certification.)

Official sources

Nathan DM et al., Translating the A1C Assay Into Estimated Average Glucose Values, Diabetes Care 2008 — The ADAG study that produced the eAG equation used on this page.
American Diabetes Association — Standards of Care in Diabetes — Where the A1C ranges quoted here are defined.
NGSP — A1C assay standardisation and certification criteria — Why two lab results half a point apart can mean nothing changed.

Frequently asked questions

If my A1C is 6.7%, what is my average glucose?

About 146 mg/dL, which is 8.1 mmol/L. That comes from multiplying 6.7 by 28.7 and subtracting 46.7 — the equation the ADAG study produced and the ADA publishes.

Which range does the ADA place 6.7% in?

The ADA describes 6.7% as the range the ADA uses to diagnose diabetes. That is a definition of a numeric range rather than a diagnosis: the ADA asks clinicians to confirm results with a repeat test and to read them alongside your history.

Is 6.7% the same in mmol/mol?

Some countries report A1C in IFCC units rather than NGSP percent. 6.7% is approximately 50 mmol/mol, so a report from the UK, Australia or much of Europe may show that number instead.

What time period does an A1C of 6.7% describe?

Roughly the previous two to three months of glucose exposure, weighted towards the most recent weeks, because A1C tracks glycation across the lifespan of red blood cells.

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