Iron & vitamins

Vitamin D (25-OH) unit converter

Vitamin D status (25-hydroxyvitamin D)

Also known as: 25-hydroxyvitamin D, 25(OH)D, 25-OH vitamin D, Calcidiol, Calcifediol, Vitamine D

Converter

Enter a value in any unit and all other units fill in.

ng/mL nmol/L µmol/L µg/dL ng/dL

Worked example

137.5 nmol/L (middle of the reference range) = 55.1 ng/mL

Conversion formulas

ng/mL	ng/mL = nmol/L × 0.4006	nmol/L = ng/mL × 2.496
µmol/L	µmol/L = nmol/L × 0.001	nmol/L = µmol/L × 1000
µg/dL	µg/dL = nmol/L × 0.04006	nmol/L = µg/dL × 24.96
ng/dL	ng/dL = nmol/L × 40.06	nmol/L = ng/dL × 0.02496

Reference range

Unit	Adults
ng/mL	30.05 – 80.13
nmol/L	75 – 200
µmol/L	0.075 – 0.2
µg/dL	3.005 – 8.012
ng/dL	3004 – 8012

Source: MedlinePlus (NLM): Vitamin D test · Last reviewed: 2026-10-14

Note from the source: Many experts recommend 30-80 ng/mL (75-200 nmol/L) (MedlinePlus). Sources disagree on the lower target: the US Institute of Medicine regards 50 nmol/L (20 ng/mL) as sufficient for most people; values below 30 nmol/L indicate deficiency

Frequently asked questions

How do I convert Vitamin D (25-OH) from nmol/L to ng/mL?

ng/mL = nmol/L × 0.4006. In the other direction: nmol/L = ng/mL × 2.496.

What is the reference range of Vitamin D (25-OH)?

For adults the range is 75 – 200 nmol/L (MedlinePlus (NLM): Vitamin D test). Reference ranges differ between laboratories and partly by sex and age; use the range printed on your lab report.

Which units are used for Vitamin D (25-OH)?

Common units are ng/mL, nmol/L, µmol/L, µg/dL, ng/dL.