mmol/L to mg/dL Blood Glucose Converter
Enter a blood glucose value in either mmol/L (the international unit used in the UK, Canada, and Australia) or mg/dL (used in the United States and parts of Europe) to convert it instantly to the other unit. The converter uses the precise glucose molar mass of 180.182 g/mol, giving you the same result clinical laboratories use. Reference ranges for normal, prediabetes, and diabetes are shown alongside your result.
Formula
Worked example
For glucose (molar mass 180.182 g/mol): 5.5 mmol/L × (180.182 / 10) = 5.5 × 18.0182 ≈ 99.1 mg/dL. Reverse: 99 mg/dL ÷ 18.0182 ≈ 5.49 mmol/L.
Why two units exist for blood glucose
Blood glucose can be reported in two equivalent units depending on where you live. The United States, Japan, and parts of continental Europe express it in milligrams per decilitre (mg/dL). Most other countries, including the United Kingdom, Canada, Australia, and much of Asia, use millimoles per litre (mmol/L), the SI unit preferred by the World Health Organization. Neither unit is more accurate than the other - they describe the same concentration through different measurement frameworks. The confusion arises most often when people travel, switch glucose meters, or read research from a different country. The conversion is straightforward: multiply mmol/L by the molar mass of glucose (180.182 g/mol) divided by 10, which gives the well-known shorthand factor of about 18.
How the conversion factor is calculated
The conversion rests on basic chemistry. One mole of glucose weighs 180.182 grams (its molar mass). A millimole is one-thousandth of a mole, so 1 mmol of glucose weighs 0.180182 grams, or 180.182 milligrams. One litre equals 10 decilitres. Combining these: 1 mmol/L = 180.182 mg per 10 dL = 18.0182 mg/dL. In clinical practice the factor is rounded to 18, which introduces less than 0.1 percent error and is well within measurement variability of modern glucose meters. This calculator uses the precise factor 18.0182 for maximum accuracy. The same molar-mass approach applies to other blood analytes such as cholesterol (386.65 g/mol, factor 38.665) and creatinine (113.12 g/mol, factor 11.312), which is why this converter includes a molecule selector.
Understanding blood glucose reference ranges
The reference ranges shown here apply to fasting measurements taken after at least 8 hours without food. Normal fasting glucose for adults without diabetes is 3.9 to 5.6 mmol/L (70 to 100 mg/dL). A reading of 5.7 to 6.9 mmol/L (101 to 124 mg/dL) on a fasting test suggests prediabetes, also called impaired fasting glucose (IFG), meaning the body is beginning to struggle with glucose regulation but has not yet crossed the diagnostic threshold for diabetes. A fasting value at or above 7.0 mmol/L (126 mg/dL) on two separate occasions meets the WHO and ADA diagnostic criteria for diabetes mellitus. Post-meal (postprandial) targets differ: two hours after eating, healthy individuals typically measure below 7.8 mmol/L (140 mg/dL), while values above 11.1 mmol/L (200 mg/dL) two hours after a glucose load indicate diabetes.
Hypoglycemia and hyperglycemia thresholds
Low blood sugar (hypoglycemia) is generally defined as glucose below 3.9 mmol/L (70 mg/dL) in people with diabetes per ADA guidelines, and below 2.8 mmol/L (50 mg/dL) is considered severe hypoglycemia requiring immediate treatment in any individual. Symptoms such as shakiness, sweating, confusion, or rapid heartbeat typically appear below 3.5 mmol/L (63 mg/dL). High blood sugar (hyperglycemia) is a hallmark of poorly controlled diabetes; sustained readings above 10 mmol/L (180 mg/dL) in people with diabetes indicate that medication, diet, or activity adjustments may be needed. A random glucose above 11.1 mmol/L (200 mg/dL) with symptoms of diabetes (increased thirst, urination, weight loss) is also diagnostic. Single readings are context-dependent - illness, stress, recent meals, and exercise all shift glucose transiently.
Blood glucose reference ranges (fasting)
| Category | mmol/L | mg/dL | Interpretation |
|---|---|---|---|
| Severe hypoglycemia | < 2.8 | < 50 | Medical emergency |
| Hypoglycemia | < 3.9 | < 70 | Dangerously low |
| Normal fasting | 3.9 - 5.6 | 70 - 100 | Healthy range |
| Prediabetes (IFG) | 5.7 - 6.9 | 101 - 124 | Impaired fasting glucose |
| Diabetes (fasting) | >= 7.0 | >= 126 | Diagnostic threshold |
| Hyperglycemia | > 11.1 | > 200 | Severely elevated |
Fasting blood glucose thresholds per WHO and American Diabetes Association guidelines. Post-meal targets differ.
Frequently asked questions
What is the formula to convert mmol/L to mg/dL?
Multiply the mmol/L value by 18.0182 (the molar mass of glucose, 180.182 g/mol, divided by 10). In everyday practice, multiplying by 18 is accurate enough: for example, 5.5 mmol/L × 18 = 99 mg/dL. This calculator uses the precise factor 18.0182 for maximum accuracy.
How do I convert mg/dL back to mmol/L?
Divide the mg/dL value by 18.0182. For example, 126 mg/dL ÷ 18.0182 = 6.99 mmol/L, the fasting diabetes diagnostic threshold. Use the "mg/dL to mmol/L" direction in this calculator to do it automatically.
Which countries use mmol/L and which use mg/dL?
The UK, Canada, Australia, New Zealand, China, and most countries that follow WHO or SI standards use mmol/L. The United States, Germany, France, Japan, Israel, and several other nations use mg/dL. If you travel or use a foreign glucose meter, check which unit your device reports before interpreting readings against local guidelines.
Is a blood glucose of 5.5 mmol/L (99 mg/dL) normal?
Yes. A fasting blood glucose of 5.5 mmol/L (99 mg/dL) falls within the normal range of 3.9 to 5.6 mmol/L (70 to 100 mg/dL) for adults without diabetes. The gauge and reference table on this page show where any reading sits within the standard clinical categories.
Does the conversion factor change for cholesterol or other analytes?
Yes. The conversion factor equals the molecule's molar mass divided by 10. Glucose has a molar mass of 180.182 g/mol (factor 18.0182), total cholesterol is 386.65 g/mol (factor 38.665), triglycerides are 885.43 g/mol (factor 88.543), and creatinine is 113.12 g/mol (factor 11.312). Select the correct molecule in the calculator to get an accurate conversion for each analyte.
Can I use this converter to diagnose diabetes?
No. A calculator converts units; it does not diagnose. Diabetes diagnosis requires clinical evaluation: two fasting glucose readings at or above 7.0 mmol/L (126 mg/dL), a 2-hour oral glucose tolerance test (OGTT) value at or above 11.1 mmol/L (200 mg/dL), an HbA1c at or above 48 mmol/mol (6.5%), or a random glucose at or above 11.1 mmol/L (200 mg/dL) with symptoms. Always consult a healthcare provider for interpretation.