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Blood sugar converter (mg/dL to mmol/L)

Glucose from mg/dL to mmol/L and back, and HbA1c to estimated average glucose (eAG) and IFCC mmol/mol, with ADA categories.

Updated Checked against 7 worked examples

mg/dL
More options
Try
Result
mmol/L
Result: 5.55 mmol/L
Shown to up to 2 decimal places, half-up
If this is a fasting reading (ADA)
Prediabetes
Informational only. Diagnosis uses laboratory plasma glucose or HbA1c tests, repeated, not a converter.

100 mg/dL is 5.55 mmol/L using 18.016 mg/dL per mmol/L; as a fasting reading it falls in the “Prediabetes” band.

Where a fasting reading sits

Diabetes range (fasting)305470100126250100 mg/dL
How it's calculated S

  1. Divide by the factor

    100 mg/dL18.016=5.55 mmol/L\frac{100\ \text{mg/dL}}{18.016} = 5.55\ \text{mmol/L}

  2. Why this factor

    Glucose weighs 180.16 g/mol, so 1 mmol/L is 18.016 mg/dL. The other common choice is 18 (a rounded factor many meters use); the two differ by less than 0.1 %.

  3. Fasting category

    As a fasting reading, 100 mg/dL is “Prediabetes” (ADA: < 70 low, 70–99 normal, 100–125 prediabetes, ≥ 126 diabetes range).

About the blood sugar converter

Glucose converts between units through its molar mass: 1 mmol/L is 18.016 mg/dL (180.16 g/mol ÷ 10), which many meters and tables round to 18. HbA1c converts to estimated average glucose (eAG) with the ADAG regression, eAG in mg/dL = 28.7 × A1c − 46.7, and to IFCC units in mmol/mol with the NGSP–IFCC master equation. Results are placed in the American Diabetes Association (ADA) categories.

People use it to read results reported in the other unit, such as a US meter against a UK lab report. 100 mg/dL is 5.55 mmol/L, the fasting level where ADA's prediabetes range begins, and an HbA1c of 7 % corresponds to an eAG of 154 mg/dL (8.6 mmol/L) and 53 mmol/mol.

The categories are population thresholds for laboratory tests confirmed by repeat testing, not for a single meter reading. eAG is a regression estimate (R² = 0.84 in the 507-person ADAG study), so an individual's measured average can differ, and anaemia or haemoglobin variants can distort HbA1c.

Worked examples

Boundary: 100 mg/dL → mmol/L

Convert
Glucose mg/dL → mmol/L
Glucose
100 mg/dL
Result
5.55 mmol/L
If this is a fasting reading (ADA)
Prediabetes

Checked against: Python 3.8 decimal: 100 / 18.016 = 5.5506; ADA fasting 100–125 mg/dL is prediabetes

7.0 mmol/L → mg/dL with factor 18

Convert
Glucose mmol/L → mg/dL
Glucose
7.0 mmol/L
mg/dL per mmol/L
18
Result
126 mg/dL
If this is a fasting reading (ADA)
Diabetes range

Checked against: NGSP eAG table pairs 126 mg/dL with 7.0 mmol/L (factor 18); ADA fasting ≥ 126 mg/dL is diabetes range

7.0 mmol/L → mg/dL with factor 18.016

Convert
Glucose mmol/L → mg/dL
Glucose
7.0 mmol/L
Result
126.11 mg/dL

Checked against: Python 3.8 decimal: 7.0 × 18.016 = 126.112

HbA1c 7% → eAG

Convert
HbA1c → estimated average glucose
HbA1c
7%
Result
154.2 mg/dL
HbA1c (IFCC)
53 mmol/mol
Estimated average glucose (mmol/L)
8.6 mmol/L
HbA1c category (ADA)
Diabetes range

Checked against: NGSP table: 7% ↔ 154 mg/dL, 8.6 mmol/L, 53 mmol/mol; ADAG 28.7 × 7 − 46.7 = 154.2

Questions

How do you convert mg/dL to mmol/L?

Divide by 18, or 18.016 exactly, from glucose's molar mass of 180.16 g/mol; to go from mmol/L to mg/dL, multiply. So 100 mg/dL is 5.55 mmol/L and 7.0 mmol/L is 126 mg/dL. The US mostly reports glucose in mg/dL, while the UK, Canada and Australia use mmol/L. The factor applies only to glucose; cholesterol and other substances have their own factors.

What is a normal blood sugar level?

For a fasting test, ADA classes below 100 mg/dL (5.6 mmol/L) as normal, 100–125 mg/dL (5.6–6.9 mmol/L) as prediabetes and 126 mg/dL (7.0 mmol/L) or more, confirmed by repeat testing, as diabetes. Two hours into a 75 g glucose tolerance test the cut-offs are 140 and 200 mg/dL (7.8 and 11.1 mmol/L). For people treated for diabetes, ADA calls a reading below 70 mg/dL (3.9 mmol/L) level 1 hypoglycaemia and below 54 mg/dL (3.0 mmol/L) level 2.

What does an HbA1c of 7 % mean?

It corresponds to an estimated average glucose of 154 mg/dL (8.6 mmol/L) over roughly the previous three months, by the ADAG equation 28.7 × 7 − 46.7, and to 53 mmol/mol in IFCC units. ADA's diagnostic threshold for diabetes is 6.5 % (48 mmol/mol), and below 7 % is the goal ADA suggests for many non-pregnant adults with diabetes, adjusted to the individual.

What HbA1c level is prediabetes?

From 5.7 % to below 6.5 % (39 to 47 mmol/mol) in the ADA criteria, with 6.5 % (48 mmol/mol) or higher, confirmed, in the diabetes range. By the ADAG equation, 5.7 % corresponds to an average glucose of 117 mg/dL (6.5 mmol/L) and 6.5 % to 140 mg/dL (7.8 mmol/L). HbA1c can mislead in anaemia, pregnancy, after blood loss or transfusion, and with some haemoglobin variants.

How accurate is the blood sugar converter?

Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 7 worked examples whose answers come from independent sources; for example, “Boundary: 100 mg/dL → mmol/L” is checked against Python 3.8 decimal: 100 / 18.016 = 5.5506; ADA fasting 100–125 mg/dL is prediabetes.

Where does the method come from?

Nathan DM et al. Translating the A1C assay into estimated average glucose values. Diabetes Care 2008;31(8):1473–1478; NGSP — HbA1c and estimated average glucose (eAG) table; NGSP — IFCC standardization of HbA1c (master equation); American Diabetes Association. Standards of Care in Diabetes—2025, sections 2 (diagnosis) and 6 (glycemic goals and hypoglycemia). Diabetes Care 2025;48(Suppl 1).

About this calculator

mg/dL=mmol/L×18.016eAGmg/dL=28.7×A1c−46.7IFCC=A1c−2.1520.09148\text{mg/dL} = \text{mmol/L} \times 18.016 \qquad \text{eAG}_{\text{mg/dL}} = 28.7 \times \text{A1c} - 46.7 \qquad \text{IFCC} = \frac{\text{A1c} - 2.152}{0.09148}

Sources

  1. Nathan DM et al. Translating the A1C assay into estimated average glucose values. Diabetes Care 2008;31(8):1473–1478
  2. NGSP — HbA1c and estimated average glucose (eAG) table
  3. NGSP — IFCC standardization of HbA1c (master equation)
  4. American Diabetes Association. Standards of Care in Diabetes—2025, sections 2 (diagnosis) and 6 (glycemic goals and hypoglycemia). Diabetes Care 2025;48(Suppl 1)

For information only, not medical advice. These formulas describe populations, not you; talk to a clinician before acting on a result.

Checked against references

7 worked examples with independently sourced answers ship with this calculator. They run in the test suite; you can run them here too.

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