How to Convert Glucose mmol/L to mg/dL
Blood glucose is reported in mg/dL in the US and much of Asia, and in mmol/L across most of Europe, Canada, Australia and the UK. The conversion factor is 18 (precisely 18.0182), which comes from the molecular weight of glucose.
Glucose mg/dL = Glucose mmol/L × 18 Glucose mmol/L = Glucose mg/dL ÷ 18 Glucose mmol/L to mg/dL Chart
| mmol/L | mg/dL | Typical band |
|---|---|---|
| 4.0 mmol/L | 72 mg/dL | Normal |
| 5.5 mmol/L | 99 mg/dL | Top of normal fasting |
| 7.0 mmol/L | 126 mg/dL | Diabetes fasting threshold |
| 10.0 mmol/L | 180 mg/dL | High |
| 11.1 mmol/L | 200 mg/dL | Random / OGTT diabetes threshold |
| 15.0 mmol/L | 270 mg/dL | Very high |
mg/dL to mmol/L Reverse Chart
| mg/dL | mmol/L |
|---|---|
| 70 mg/dL | 3.9 mmol/L |
| 100 mg/dL | 5.6 mmol/L |
| 126 mg/dL | 7.0 mmol/L |
| 140 mg/dL | 7.8 mmol/L |
| 200 mg/dL | 11.1 mmol/L |
Fasting Glucose Reference Ranges
Commonly cited fasting (no food for 8+ hours) blood glucose bands:
| Category | mg/dL | mmol/L |
|---|---|---|
| Hypoglycemia (low) | Below 70 mg/dL | Below 3.9 mmol/L |
| Normal | 70–99 mg/dL | 3.9–5.5 mmol/L |
| Prediabetes | 100–125 mg/dL | 5.6–6.9 mmol/L |
| Diabetes | 126 mg/dL and above | 7.0 mmol/L and above |
2-Hour OGTT (Glucose Tolerance Test) Ranges
Values measured 2 hours after a 75 g glucose drink:
| Category | mg/dL | mmol/L |
|---|---|---|
| Normal | Below 140 mg/dL | Below 7.8 mmol/L |
| Prediabetes (IGT) | 140–199 mg/dL | 7.8–11.0 mmol/L |
| Diabetes | 200 mg/dL and above | 11.1 mmol/L and above |
A random (non-fasting) glucose of 200 mg/dL (11.1 mmol/L) or higher with classic symptoms also points to diabetes. Diagnosis is confirmed with repeat testing.
Low Blood Sugar (Hypoglycemia)
A glucose below 70 mg/dL (3.9 mmol/L) is generally considered low. Symptoms include shakiness, sweating, hunger and confusion; severe hypoglycemia needs prompt treatment with fast-acting carbohydrate.
Glucose and HbA1c
A single glucose reading is a snapshot. HbA1c reflects your average glucose over the past 2–3 months, and the estimated average glucose (eAG) derived from it is reported in both mg/dL and mmol/L. Work it out on the HbA1c conversion calculator.
Worked Example
Suppose your meter reads 7.8 mmol/L and you want mg/dL:
7.8 × 18 = 140 mg/dL 140 mg/dL is the 2-hour OGTT prediabetes threshold. For the reverse direction, a fasting 126 mg/dL is 7.0 mmol/L, the diabetes cut-off.
Frequently Asked Questions
How do you convert glucose mmol/L to mg/dL?
Multiply mmol/L by 18. For example, 5.5 mmol/L is about 99 mg/dL.
What is a normal fasting blood sugar?
70–99 mg/dL (3.9–5.5 mmol/L). 126 mg/dL (7.0 mmol/L) or above is the diabetes threshold.
Why is glucose multiplied by 18?
The factor comes from glucose's molecular weight of about 180.16 g/mol.
What blood sugar is too low?
Below 70 mg/dL (3.9 mmol/L) is hypoglycemia and may need treatment.
References
- American Diabetes Association — fasting, OGTT and random glucose diagnostic thresholds (Standards of Care).
- Glucose conversion factor 18.0182 (mg/dL ↔ mmol/L), derived from the molecular weight of glucose (180.16 g/mol).
Conclusion
Converting blood glucose between mmol/L and mg/dL is a simple ×18. The number that matters is the range it lands in — normal, prediabetes, or diabetes — and how it fits with your fasting status and HbA1c. Interpret results with your healthcare provider.