Converting Mass Concentration to Molar Concentration
In clinical diagnostics, lab results are often reported in two different formats: Mass Concentration (nanograms per milliliter, ng/mL) or Molar Concentration (nanomoles per liter, nmol/L). Converting between these units is essential for comparing patient results against international clinical guidelines.
The Role of Molecular Weight
Unlike simple metric conversions, converting ng/mL to nmol/L requires the Molecular Weight (MW) of the specific substance being measured. This is because a 'mole' represents a specific number of molecules, and different substances (like Progesterone vs. Vitamin D) have different weights.
The standard conversion formula used by this tool is:
- nmol/L = (ng/mL × 1000) / Molecular Weight
- ng/mL = (nmol/L × Molecular Weight) / 1000
Common Molecular Weights for Reference
| Substance | Approx. Molecular Weight (g/mol) |
|---|---|
| Progesterone | 314.47 |
| Testosterone | 288.42 |
| 25-Hydroxy Vitamin D | 400.64 |
| Cortisol | 362.46 |
Formula:
Conversion Formula:
nmol/L = (ng/mL × 1000) / Molecular Weight