Blood glucose converts between units with one factor: 1 mmol/L = 18 mg/dL. So 5.5 mmol/L equals 99 mg/dL — the top of the normal fasting range — and 7.0 mmol/L equals 126 mg/dL, the fasting diabetes threshold. This free converter switches any value instantly and shows the reference ranges in both systems.
Blood sugar is measured in two different units around the world — mg/dL in the United States, Turkey and much of the Middle East; mmol/L in the UK, Europe, Canada and Australia — and a glucose value in the wrong unit is meaningless. This blood sugar converter switches instantly between the two, with the reference ranges beside it so the converted number makes sense.
Convert below, then read on: the conversion factor, the full chart, and what the normal ranges are in both unit systems.
Blood Sugar Converter
Convert glucose between mg/dL and mmol/L.
mmol/L to mg/dL: the conversion
One conversion factor covers everything: 1 mmol/L = 18 mg/dL (precisely 18.016, from glucose’s molecular weight).
- mmol/L → mg/dL: multiply by 18. A reading of 5.5 mmol/L = 99 mg/dL.
- mg/dL → mmol/L: divide by 18. A reading of 126 mg/dL = 7.0 mmol/L.
Blood sugar conversion chart
| mg/dL | mmol/L | Context (fasting) |
|---|---|---|
| 54 | 3.0 | Serious hypoglycemia — treat immediately |
| 70 | 3.9 | Lower limit of normal; below this is hypoglycemia |
| 99 | 5.5 | Upper limit of normal fasting glucose |
| 126 | 7.0 | Diabetes threshold (fasting, confirmed twice) |
| 140 | 7.8 | Upper limit of normal 2 hours after eating |
| 180 | 10.0 | Common upper target after meals in diabetes care |
| 200 | 11.1 | Diabetes threshold for a random reading with symptoms |
Normal blood sugar levels in both units
Fasting: 70–99 mg/dL (3.9–5.5 mmol/L) is normal; 100–125 mg/dL (5.6–6.9 mmol/L) is impaired fasting glucose — the prediabetes zone; 126 mg/dL (7.0 mmol/L) or higher, confirmed on two occasions, meets the diabetes threshold. Two hours after meals, below 140 mg/dL (7.8 mmol/L) is normal. Single readings are snapshots — diagnosis always rests on confirmed repeat tests and often on the three-month average, which our A1c calculator converts and explains. For the full clinical picture, see the type 2 diabetes guide.
Why two units exist — and where mix-ups happen
mg/dL expresses weight of glucose per volume; mmol/L counts molecules — the international (SI) convention. The confusion is practical, not academic: travellers with meters bought abroad, families comparing readings across countries, and research papers in SI units all trip over the factor of 18. A tell-tale check: mmol/L values in daily life are small numbers (3–20); mg/dL values are large (60–360). A “glucose of 6.2” is almost certainly mmol/L — 112 mg/dL — not a dangerously low 6.2 mg/dL.
This tool is informational. It converts units and does not interpret your health. Diagnosis and glucose targets belong to your physician — and readings below 70 mg/dL (3.9 mmol/L) with symptoms need treatment now, not conversion.
Frequently asked questions
How do I convert mmol/L to mg/dL?
Multiply by 18. So 5.0 mmol/L = 90 mg/dL, and 7.0 mmol/L = 126 mg/dL. To go the other way, divide by 18.
What is a normal blood sugar level?
Fasting: 70–99 mg/dL (3.9–5.5 mmol/L). Two hours after eating: below 140 mg/dL (7.8 mmol/L). Values above these on repeat testing deserve medical review.
What is 126 mg/dL in mmol/L — and why does it matter?
7.0 mmol/L. It is the fasting threshold for diagnosing diabetes when confirmed on two occasions.
Why does my meter read in different units than my lab report?
Meters follow the convention of the country they were sold in. Many can be switched in settings — worth doing, because comparing across units invites errors of a factor of 18.
What blood sugar level is dangerously low?
Below 70 mg/dL (3.9 mmol/L) is hypoglycemia; below 54 mg/dL (3.0 mmol/L) is serious and needs immediate fast-acting carbohydrate — and medical advice if it recurs.
Numbers are a starting point — not a diagnosis
If your results raise questions, Acibadem specialists can review your situation properly: share your case and receive a free, no-obligation medical opinion from the relevant department.