Bilirubin and vitamin C are reported in µmol/L in SI laboratories, and vitamin D is reported in nmol/L or ng/mL. Our converters work in mmol/L and mg/dL and offer a µmol/L option where labs use it. The notes below give the direct factor for the unit your report most likely uses.
Converters in This Group
| Test | mmol/L → mg/dL factor | Convert | Reverse |
|---|---|---|---|
| Total Bilirubin | × 58.47 | Total Bilirubin mmol/L to mg/dL | Total Bilirubin mg/dL to mmol/L |
| Vitamin D | × 40.06 | Vitamin D mmol/L to mg/dL | Vitamin D mg/dL to mmol/L |
| Vitamin C | × 17.61 | Vitamin C mmol/L to mg/dL | Vitamin C mg/dL to mmol/L |
To convert mg/dL to mmol/L, divide by the same factor.
About These Tests
Total Bilirubin
A breakdown product of red blood cells, raised in jaundice. SI labs report µmol/L: 1 mg/dL = 17.1 µmol/L.
Vitamin D
Measured as 25-hydroxyvitamin D. Labs report ng/mL or nmol/L (1 ng/mL = 2.496 nmol/L); mmol/L and mg/dL are rarely used for this test.
Vitamin C
Plasma ascorbic acid, reported in µmol/L. Below about 11 µmol/L (0.2 mg/dL) indicates deficiency.
How the Factors Are Calculated
Each factor is the molar mass of the substance (g/mol) divided by 10. Factors were last verified on 24 September 2026. Read more in our editorial policy.
Sources
- Holick MF et al. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab 2011;96:1911–1930.
- IUPAC Commission on Isotopic Abundances and Atomic Weights. Standard atomic weights (used for all molar masses).
Reference ranges vary between laboratories. Use the range printed on your own report and discuss results with your doctor.