How to Convert ng/mL to nmol/L
ng/mL and nmol/L both describe concentration, but they use different measurement systems. ng/mL is a mass concentration, while nmol/L is a molar concentration. To move from mass to moles, the calculator needs the molecular weight of the selected molecule.
nmol/L = (ng/mL x 1000) / molecular weight ng/mL = (nmol/L x molecular weight) / 1000 This is why vitamin D, testosterone, estradiol, cortisol, progesterone, and thyroid hormones do not share one universal conversion factor.
How to Use This Calculator
First, select the molecule from the dropdown. Then choose the conversion direction, enter your value, and review the converted result. The formula panel updates automatically, so you can see exactly how the result was calculated.
The default example uses vitamin D because many lab reports and reference ranges switch between ng/mL and nmol/L. A vitamin D result of 20 ng/mL is approximately 49.92 nmol/L.
Why Molecular Weight Matters
A nanogram measures mass. A nanomole counts molecules. Molecular weight connects those two systems by telling the calculator how much one mole of the selected substance weighs.
For vitamin D, the molecular weight is 400.64 g/mol, so 1 nmol/L equals 0.4006 ng/mL. For testosterone, the molecular weight is 288.42 g/mol, so 1 nmol/L equals 0.2884 ng/mL. Because these factors are different, the molecule selection is essential.
Supported Molecules and Conversion Factors
Use the correct molecule before comparing your result with a reference interval. The table below shows the molecular weights used by the calculator.
| Molecule | Molecular weight | 1 ng/mL equals | Common use |
|---|---|---|---|
| Vitamin D (25-Hydroxyvitamin D) | 400.64 g/mol | 2.50 nmol/L | Vitamin D status and supplementation tracking |
| Testosterone | 288.42 g/mol | 3.47 nmol/L | Androgen and hormone assessment |
| Estradiol (E2) | 272.38 g/mol | 3.67 nmol/L | Estrogen and fertility-related testing |
| Cortisol | 362.46 g/mol | 2.76 nmol/L | Adrenal and stress hormone assessment |
| Progesterone | 314.47 g/mol | 3.18 nmol/L | Ovulation, luteal phase, and pregnancy-related testing |
| Vitamin A (Retinol) | 416.65 g/mol | 2.40 nmol/L | Vitamin A and retinol status |
| Vitamin E (Alpha-Tocopherol) | 384.65 g/mol | 2.60 nmol/L | Vitamin E antioxidant status |
| Aldosterone | 286.46 g/mol | 3.49 nmol/L | Adrenal and blood pressure-related testing |
| Dehydroepiandrosterone (DHEA) | 346.46 g/mol | 2.89 nmol/L | Adrenal androgen assessment |
| Vitamin B12 (Cobalamin) | 453.59 g/mol | 2.20 nmol/L | B12 status and anemia evaluation |
| Folate (Folic Acid) | 441.4 g/mol | 2.27 nmol/L | Folate status and anemia evaluation |
| Melatonin | 312.45 g/mol | 3.20 nmol/L | Sleep and circadian rhythm assessment |
| Thyroxine (T4) | 776.87 g/mol | 1.29 nmol/L | Thyroid hormone testing |
| Triiodothyronine (T3) | 650.97 g/mol | 1.54 nmol/L | Thyroid hormone testing |
Common ng/mL to nmol/L Examples
These examples show why the selected molecule matters. The same ng/mL number can convert to a different nmol/L value depending on molecular weight.
| Molecule | ng/mL | nmol/L | Context |
|---|---|---|---|
| Vitamin D | 20 ng/mL | 49.92 nmol/L | Common vitamin D comparison |
| Vitamin D | 30 ng/mL | 74.88 nmol/L | Often used as a sufficiency target |
| Testosterone | 5 ng/mL | 17.34 nmol/L | Common adult male example |
| Progesterone | 10 ng/mL | 31.80 nmol/L | Luteal phase example |
| Cortisol | 180 ng/mL | 496.61 nmol/L | Morning cortisol example |
| Folate | 8 ng/mL | 18.12 nmol/L | Folate status example |
Vitamin D ng/mL to nmol/L
Vitamin D is one of the most common reasons people need this conversion. Many US reports show 25-hydroxyvitamin D in ng/mL, while many international references use nmol/L.
For vitamin D, multiply ng/mL by about 2.496 to get nmol/L. For example, 30 ng/mL is about 74.88 nmol/L. Use the calculator above when you want exact results with the displayed molecular weight.
Frequently Asked Questions
How do you convert ng/mL to nmol/L?
Multiply the ng/mL value by 1000, then divide by the molecular weight of the molecule. For vitamin D, 20 ng/mL x 1000 / 400.64 = 49.92 nmol/L.
Is ng/mL to nmol/L the same for every molecule?
No. The conversion changes by molecule because molecular weight changes. Always select the exact substance before converting.
What is 20 ng/mL vitamin D in nmol/L?
20 ng/mL vitamin D equals about 49.92 nmol/L when using a molecular weight of 400.64 g/mol.
What is 5 ng/mL testosterone in nmol/L?
5 ng/mL testosterone equals about 17.34 nmol/L when using a molecular weight of 288.42 g/mol.
Can I use this calculator for prescription drugs?
This page is designed for hormones, vitamins, and common lab analytes. For therapeutic drug monitoring, use a drug-specific calculator when available, such as the Valproic Acid Unit Converter.
Conclusion
The ng/mL to nmol/L conversion is simple once the molecular weight is known. This calculator handles the formula for you, shows the active conversion factor, and lets you switch direction when needed.
Use it to compare lab reports, review international reference ranges, or understand hormone and vitamin results reported in different units. Always use clinical context and professional guidance when interpreting medical test results.