This nmol/L to ng/mL calculator converts between molar concentration and mass concentration for molecules commonly measured in lab reports, including 25-hydroxyvitamin D, testosterone, estradiol, cortisol, progesterone, aldosterone, DHEA, folic acid, melatonin, T3, and T4. If your result is reported in ng/dL instead, use the nmol/L to ng/dL calculator.
The conversion is molecule-specific. nmol/L counts the amount of molecule in a liter, while ng/mL measures mass in a milliliter. Because each molecule has a different molecular weight, the same nmol/L number can become a different ng/mL value.
Quick nmol/L to ng/mL Reference
These common conversion factors are based on molecular weight. Use the calculator above when switching molecules or converting ng/mL back to nmol/L.
nmol/L to ng/mL Formula
To convert nmol/L to ng/mL, multiply the nmol/L value by the molecular weight and divide by 1000. In the calculator, this is shown as a molecule-specific factor.
ng/mL = nmol/L x molecular weight / 1000 For 25-hydroxyvitamin D, the factor is about 0.4006. That means 50 nmol/L x 0.4006 = 20.03 ng/mL. For testosterone, the factor is about 0.2884, so the same 50 nmol/L would convert to 14.42 ng/mL.
ng/mL to nmol/L Formula
To convert ng/mL back to nmol/L, divide the ng/mL value by the molecule-specific factor. This is useful when comparing results from labs or articles that use different unit systems.
nmol/L = ng/mL / conversion factor Vitamin D nmol/L to ng/mL Chart
25-hydroxyvitamin D is one of the most common nmol/L to ng/mL conversions. This chart uses 1 nmol/L vitamin D = 0.4006 ng/mL.
| Vitamin D nmol/L | Vitamin D ng/mL |
|---|---|
| 25.0 nmol/L | 10.0 ng/mL |
| 30.0 nmol/L | 12.0 ng/mL |
| 40.0 nmol/L | 16.0 ng/mL |
| 50.0 nmol/L | 20.0 ng/mL |
| 75.0 nmol/L | 30.0 ng/mL |
| 100.0 nmol/L | 40.1 ng/mL |
| 125.0 nmol/L | 50.1 ng/mL |
| 150.0 nmol/L | 60.1 ng/mL |
| 200.0 nmol/L | 80.1 ng/mL |
| 250.0 nmol/L | 100.2 ng/mL |
Conversion Factors by Molecule
Use the correct molecule row before converting. A vitamin D factor is not correct for testosterone, progesterone, cortisol, or thyroid hormones.
| Molecule | Molecular weight | nmol/L to ng/mL | ng/mL to nmol/L |
|---|---|---|---|
| 25-Hydroxyvitamin D | 400.64 g/mol | multiply by 0.4006 | divide by 0.4006 |
| Testosterone | 288.42 g/mol | multiply by 0.2884 | divide by 0.2884 |
| Estradiol (E2) | 272.38 g/mol | multiply by 0.2724 | divide by 0.2724 |
| Cortisol | 362.46 g/mol | multiply by 0.3625 | divide by 0.3625 |
| Progesterone | 314.47 g/mol | multiply by 0.3145 | divide by 0.3145 |
| Aldosterone | 360.44 g/mol | multiply by 0.3604 | divide by 0.3604 |
| DHEA | 288.43 g/mol | multiply by 0.2884 | divide by 0.2884 |
| DHEA sulfate | 368.49 g/mol | multiply by 0.3685 | divide by 0.3685 |
| Folic acid | 441.4 g/mol | multiply by 0.4414 | divide by 0.4414 |
| Melatonin | 232.28 g/mol | multiply by 0.2323 | divide by 0.2323 |
| T3 (Triiodothyronine) | 650.97 g/mol | multiply by 0.6510 | divide by 0.6510 |
| T4 (Thyroxine) | 776.87 g/mol | multiply by 0.7769 | divide by 0.7769 |
Why Molecular Weight Matters
nmol/L is based on the number of molecules, not their mass. ng/mL is based on mass. A larger molecule contributes more nanograms than a smaller molecule at the same molar concentration, which is why molecular weight is the bridge between the two units.
This is also why a single universal shortcut is not accurate. Vitamin D uses a factor close to 0.4006, testosterone uses about 0.2884, progesterone uses about 0.3145, and cortisol uses about 0.3625.
Important Safety Note
This page is only for unit conversion. It does not interpret hormone, vitamin, thyroid, adrenal, or fertility-related lab results. Reference ranges vary by lab method, age, sex, pregnancy status, medication use, and clinical context.
Frequently Asked Questions
How do you convert nmol/L to ng/mL?
Multiply the nmol/L value by the molecule-specific factor. The factor is the molecular weight divided by 1000.
How do you convert ng/mL to nmol/L?
Divide the ng/mL value by the molecule-specific conversion factor. For example, 20 ng/mL vitamin D divided by 0.4006 is about 49.9 nmol/L.
What is 50 nmol/L vitamin D in ng/mL?
50 nmol/L 25-hydroxyvitamin D is about 20 ng/mL. The calculation is 50 x 0.4006.
Is nmol/L to ng/mL the same for testosterone and vitamin D?
No. Testosterone uses about 0.2884 for nmol/L to ng/mL, while 25-hydroxyvitamin D uses about 0.4006. The conversion depends on molecular weight.
References for Conversion Factors
Conversion factors were checked against public laboratory unit conversion references, including Mayo Clinic Laboratories SI conversion tables, UNITSLAB hormone conversion pages, and molecular-weight based conversion formulas.