25-hydroxyvitamin D conversion: ng/mL to nmol/L
For 25-hydroxyvitamin D, 1 ng/mL = 2.49596 nmol/L, and 1 nmol/L = 0.400647 ng/mL.
Common values
ng/mL to nmol/L
| ng/mL | nmol/L |
|---|---|
| 5 | 12 |
| 10 | 25 |
| 12 | 30 |
| 15 | 37 |
| 20 | 50 |
| 25 | 62 |
| 30 | 75 |
| 40 | 100 |
| 50 | 125 |
| 60 | 150 |
| 80 | 200 |
| 100 | 250 |
nmol/L to ng/mL
| nmol/L | ng/mL |
|---|---|
| 10 | 4.0 |
| 20 | 8.0 |
| 25 | 10.0 |
| 30 | 12.0 |
| 40 | 16.0 |
| 50 | 20.0 |
| 75 | 30.0 |
| 100 | 40.1 |
| 125 | 50.1 |
| 150 | 60.1 |
| 200 | 80.1 |
| 250 | 100.2 |
Each converted value is worked out in full and then rounded: nmol/L to whole numbers and ng/mL to one decimal place.
Source: molar masses summed from the IUPAC CIAAW abridged standard atomic weights, 2024.
The values are facts and free to use; this table’s selection and presentation are © 2026 ScienceQuest.
Why the factor is specific to 25-hydroxyvitamin D
25-hydroxyvitamin D3 (calcifediol), C₂₇H₄₄O₂, has a molar mass of 400.647 g/mol, summed from the standard atomic weights of its atoms. A result in ng/mL is a mass and one in nmol/L an amount of substance, so converting divides by the molar mass and multiplies by 1000 for the millilitres in a litre: 1 ng/mL = 1000 ÷ 400.647 = 2.49596 nmol/L.
A factor fits one analyte only: 1 ng/mL of progesterone is 3.17996 nmol/L, as the progesterone conversion table shows.
Laboratories apply this factor to total 25-hydroxyvitamin D. The D2 form, C₂₈H₄₄O₂, is 412.658 g/mol, so the factor overstates a D2 result in nmol/L by about 3 %.
- nmol/L = ng/mL × 1000 ÷ 400.647
- ng/mL = nmol/L × 400.647 ÷ 1000
Which countries report which unit
American laboratories usually report 25-hydroxyvitamin D in ng/mL; British, Canadian and Australian ones report nmol/L.
Worked example
- 20 ng/mL in nmol/L
- = 20 × 1000 ÷ 400.647
- = 49.9193 nmol/L