mmol/L to mg/dL Calculator
This calculator converts concentration values between mmol/L (millimoles per litre) and mg/dL (milligrams per decilitre), the two units used to report blood test results such as blood glucose, cholesterol, triglycerides, urea, calcium and magnesium. New Zealand, Australia, the United Kingdom and most of Europe report these results in mmol/L, while the United States and Japan use mg/dL, so you need this conversion whenever you compare a NZ lab report with an imported glucose meter or an overseas reference range. You start by selecting the substance from the dropdown, since each one has its own molecular weight and therefore its own conversion factor, then choose the direction you want to convert and type in your value. The calculator instantly shows the converted result, the input you entered, and the exact conversion factor used, along with the underlying formula and a step-by-step breakdown of the calculation. A worked example using a fasting blood glucose of 5.5 mmol/L (99.1 mg/dL) is shown alongside your own figures, and a reference table lists common values such as fasting glucose targets and cholesterol thresholds in both units for quick comparison. A swap button lets you flip the conversion direction instantly. This tool performs the mathematical conversion only; it does not offer medical advice, and you should discuss what any result means for your health with a doctor or other qualified healthcare professional.
1. Select Substance
2. Result
Common Reference Values
| Measurement | mmol/L | mg/dL | Context |
|---|
Calculation Steps
Worked Example (Defaults)
How the mmol/L to mg/dL Conversion Works
Both mmol/L (millimoles per litre) and mg/dL (milligrams per decilitre) measure the concentration of a substance in blood or another fluid. They differ in the unit used to express the amount of substance. The conversion between them depends on the molecular weight of the specific substance being measured.
The formula is:
- mg/dL = mmol/L x (molecular weight / 10)
- mmol/L = mg/dL / (molecular weight / 10)
The division by 10 converts between litres and decilitres (1 L = 10 dL). This means the conversion factor is substance-specific and you cannot use a single number for all tests.
Conversion Factors by Substance
| Substance | Molecular Weight (g/mol) | Factor (MW / 10) | Example |
|---|---|---|---|
| Glucose (blood sugar) | 180.182 | 18.0182 | 5.5 mmol/L = 99.1 mg/dL |
| Cholesterol (total, LDL, HDL) | 386.65 | 38.665 | 5.0 mmol/L = 193.3 mg/dL |
| Triglycerides | 885.43 | 88.543 | 1.5 mmol/L = 132.8 mg/dL |
| Urea | 60.06 | 6.006 | 7.0 mmol/L = 42.0 mg/dL |
| Creatinine* | 113.12 | 0.011312* | 80 umol/L = 0.9 mg/dL |
| Calcium | 40.08 | 4.008 | 2.5 mmol/L = 10.02 mg/dL |
| Magnesium | 24.31 | 2.431 | 1.0 mmol/L = 2.43 mg/dL |
* Creatinine is measured in umol/L in New Zealand rather than mmol/L, so it uses a different base unit from the substances above. Multiply umol/L by 0.011312 to get mg/dL (for example, 80 umol/L = 0.9 mg/dL). Because its base unit differs, creatinine is shown here for reference only and is not part of the substance selector above. Urea is converted using the standard molecular-weight factor (60.06 / 10 = 6.006), giving whole-molecule urea rather than blood urea nitrogen (BUN).
Blood Glucose: NZ vs US Reference Ranges
| Category | NZ/UK (mmol/L) | US (mg/dL) |
|---|---|---|
| Normal fasting glucose | 4.0 to 5.9 | 72 to 106 |
| Pre-diabetes (impaired fasting) | 6.0 to 6.9 | 108 to 124 |
| Diabetes diagnosis (fasting) | 7.0 or above | 126 or above |
| Hypoglycaemia | Below 4.0 | Below 72 |
| Target post-meal (2 hr, diabetic) | Below 8.5 | Below 153 |
Why Different Countries Use Different Units
The United States, Japan, and some other countries adopted mg/dL as the standard for reporting blood glucose and cholesterol when clinical laboratory testing became widespread in the mid-20th century. New Zealand, Australia, the United Kingdom, Canada, and most of Europe adopted the International System of Units (SI), which uses mmol/L, as part of broader metrication in medicine during the 1970s and 1980s.
This means that if you read an American diabetes study, a US glucose monitor, or a US food label about blood sugar, the numbers will typically be about 18 times larger than the equivalent NZ value. A reading of 100 mg/dL (US normal fasting) is approximately 5.6 mmol/L in NZ terms.
Practical Tips for Using This Calculator
- If you are comparing an imported glucose monitor to a NZ laboratory result, use the glucose factor (18.0182).
- For cholesterol, the same factor (38.665) applies to total cholesterol, LDL, and HDL since they are all cholesterol molecules.
- Triglycerides use a much larger factor (88.543) because the molecule is much heavier than cholesterol.
- If your lab report uses different units from your doctor's reference chart, use this calculator to reconcile them.
- Always confirm clinical interpretation with a healthcare professional; this calculator provides the mathematical conversion only.
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Sources and method: Molecular weights from IUPAC (International Union of Pure and Applied Chemistry) and PubChem. Conversion formula: mg/dL = mmol/L x (molecular weight / 10). Blood glucose reference ranges: Ministry of Health New Zealand / Diabetes New Zealand. Cholesterol reference ranges: Heart Foundation of New Zealand.
This calculator provides the mathematical unit conversion only. It does not constitute medical advice. Clinical interpretation of laboratory results should be discussed with a qualified healthcare professional. Reference ranges may vary between laboratories.