mg/dL vs mmol/L: How to Convert Blood Test Units
Why two systems exist
The United States and a few other countries report many results in conventional units such as mg/dL (milligrams per decilitre). Most of the world uses SI units such as mmol/L (millimoles per litre). Neither is wrong, but you cannot compare numbers across them without converting.
Conversion factors for common tests
| Test | mmol/L → mg/dL | mg/dL → mmol/L |
|---|---|---|
| Glucose | × 18.016 | × 0.0555 |
| Total, LDL and HDL cholesterol | × 38.67 | × 0.0259 |
| Triglycerides | × 88.57 | × 0.0113 |
| Calcium | × 4.008 | × 0.2495 |
| Urea (as urea) | × 6.006 | × 0.1665 |
| Creatinine (µmol/L → mg/dL) | ÷ 88.4 | × 88.4 (to µmol/L) |
| Uric acid (µmol/L → mg/dL) | ÷ 59.48 | × 59.48 (to µmol/L) |
| Bilirubin (µmol/L → mg/dL) | ÷ 17.1 | × 17.1 (to µmol/L) |
| Hemoglobin (g/L → g/dL) | ÷ 10 | × 10 |
| Vitamin D (nmol/L → ng/mL) | ÷ 2.496 | × 2.496 |
| HbA1c (mmol/mol → %) | % = 0.09148 × mmol/mol + 2.152 | |
Use the free converter to do it instantly.
Worked examples
- Glucose 5.5 mmol/L × 18.016 = 99 mg/dL, the top of the normal fasting range.
- Cholesterol 5.2 mmol/L × 38.67 = 201 mg/dL, just over the “desirable” limit.
- Creatinine 80 µmol/L ÷ 88.4 = 0.90 mg/dL.
- HbA1c 48 mmol/mol = 0.09148 × 48 + 2.152 = 6.5%, the diabetes threshold.
Why it matters for tracking
If you move country, change lab or use a different report, the unit can change and a chart that mixes the two shows a false jump. Always convert to a single unit before comparing, as covered in tracking results over time. Labgist converts the common units on upload and keeps your original reading.
Quick sanity checks
- Fasting glucose around 5 is mmol/L. Around 90 is mg/dL.
- Total cholesterol around 5 is mmol/L. Around 190 is mg/dL.
- Creatinine around 80 is µmol/L. Around 0.9 is mg/dL.
Frequently asked questions
How do I convert glucose from mmol/L to mg/dL?
Multiply the mmol/L value by 18.016. For example, 5.5 mmol/L is about 99 mg/dL.
Why is the cholesterol factor different from the glucose factor?
Conversions depend on molecular weight. Each substance has a different weight, so each has its own factor.
Which countries use mg/dL?
The United States and several others use mg/dL for glucose and cholesterol. The UK, EU, Canada, Australia and many other countries use mmol/L, and India commonly uses mg/dL.